diff --git a/lesson2/.idea/checkstyle-idea.xml b/lesson2/.idea/checkstyle-idea.xml
deleted file mode 100644
index 294cf23..0000000
--- a/lesson2/.idea/checkstyle-idea.xml
+++ /dev/null
@@ -1,16 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="CheckStyle-IDEA">
-    <option name="configuration">
-      <map>
-        <entry key="checkstyle-version" value="8.12" />
-        <entry key="copy-libs" value="false" />
-        <entry key="location-0" value="BUNDLED:(bundled):Sun Checks" />
-        <entry key="location-1" value="BUNDLED:(bundled):Google Checks" />
-        <entry key="scan-before-checkin" value="false" />
-        <entry key="scanscope" value="JavaOnly" />
-        <entry key="suppress-errors" value="false" />
-      </map>
-    </option>
-  </component>
-</project>
\ No newline at end of file
diff --git a/lesson2/.idea/codeStyles/codeStyleConfig.xml b/lesson2/.idea/codeStyles/codeStyleConfig.xml
deleted file mode 100644
index 8dfc3f7..0000000
--- a/lesson2/.idea/codeStyles/codeStyleConfig.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<component name="ProjectCodeStyleConfiguration">
-  <state>
-    <option name="PREFERRED_PROJECT_CODE_STYLE" value="Briefcase copy" />
-  </state>
-</component>
\ No newline at end of file
diff --git a/lesson2/.idea/gradle.xml b/lesson2/.idea/gradle.xml
index 02e891c..96ec7f5 100644
--- a/lesson2/.idea/gradle.xml
+++ b/lesson2/.idea/gradle.xml
@@ -5,13 +5,12 @@
       <GradleProjectSettings>
         <option name="distributionType" value="LOCAL" />
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleHome" value="/usr/local/Cellar/gradle/4.10/libexec" />
+        <option name="gradleHome" value="/usr/local/Cellar/gradle/4.10.2/libexec" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />
           </set>
         </option>
-        <option name="useAutoImport" value="true" />
       </GradleProjectSettings>
     </option>
   </component>
diff --git a/lesson2/.idea/uiDesigner.xml b/lesson2/.idea/uiDesigner.xml
deleted file mode 100644
index e96534f..0000000
--- a/lesson2/.idea/uiDesigner.xml
+++ /dev/null
@@ -1,124 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="Palette2">
-    <group name="Swing">
-      <item class="com.intellij.uiDesigner.HSpacer" tooltip-text="Horizontal Spacer" icon="/com/intellij/uiDesigner/icons/hspacer.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="1" hsize-policy="6" anchor="0" fill="1" />
-      </item>
-      <item class="com.intellij.uiDesigner.VSpacer" tooltip-text="Vertical Spacer" icon="/com/intellij/uiDesigner/icons/vspacer.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="1" anchor="0" fill="2" />
-      </item>
-      <item class="javax.swing.JPanel" icon="/com/intellij/uiDesigner/icons/panel.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3" />
-      </item>
-      <item class="javax.swing.JScrollPane" icon="/com/intellij/uiDesigner/icons/scrollPane.png" removable="false" auto-create-binding="false" can-attach-label="true">
-        <default-constraints vsize-policy="7" hsize-policy="7" anchor="0" fill="3" />
-      </item>
-      <item class="javax.swing.JButton" icon="/com/intellij/uiDesigner/icons/button.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="3" anchor="0" fill="1" />
-        <initial-values>
-          <property name="text" value="Button" />
-        </initial-values>
-      </item>
-      <item class="javax.swing.JRadioButton" icon="/com/intellij/uiDesigner/icons/radioButton.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
-        <initial-values>
-          <property name="text" value="RadioButton" />
-        </initial-values>
-      </item>
-      <item class="javax.swing.JCheckBox" icon="/com/intellij/uiDesigner/icons/checkBox.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="3" anchor="8" fill="0" />
-        <initial-values>
-          <property name="text" value="CheckBox" />
-        </initial-values>
-      </item>
-      <item class="javax.swing.JLabel" icon="/com/intellij/uiDesigner/icons/label.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="0" anchor="8" fill="0" />
-        <initial-values>
-          <property name="text" value="Label" />
-        </initial-values>
-      </item>
-      <item class="javax.swing.JTextField" icon="/com/intellij/uiDesigner/icons/textField.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
-          <preferred-size width="150" height="-1" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JPasswordField" icon="/com/intellij/uiDesigner/icons/passwordField.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
-          <preferred-size width="150" height="-1" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JFormattedTextField" icon="/com/intellij/uiDesigner/icons/formattedTextField.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1">
-          <preferred-size width="150" height="-1" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JTextArea" icon="/com/intellij/uiDesigner/icons/textArea.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JTextPane" icon="/com/intellij/uiDesigner/icons/textPane.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JEditorPane" icon="/com/intellij/uiDesigner/icons/editorPane.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JComboBox" icon="/com/intellij/uiDesigner/icons/comboBox.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="0" hsize-policy="2" anchor="8" fill="1" />
-      </item>
-      <item class="javax.swing.JTable" icon="/com/intellij/uiDesigner/icons/table.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JList" icon="/com/intellij/uiDesigner/icons/list.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="2" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JTree" icon="/com/intellij/uiDesigner/icons/tree.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3">
-          <preferred-size width="150" height="50" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JTabbedPane" icon="/com/intellij/uiDesigner/icons/tabbedPane.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
-          <preferred-size width="200" height="200" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JSplitPane" icon="/com/intellij/uiDesigner/icons/splitPane.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="3" hsize-policy="3" anchor="0" fill="3">
-          <preferred-size width="200" height="200" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JSpinner" icon="/com/intellij/uiDesigner/icons/spinner.png" removable="false" auto-create-binding="true" can-attach-label="true">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
-      </item>
-      <item class="javax.swing.JSlider" icon="/com/intellij/uiDesigner/icons/slider.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
-      </item>
-      <item class="javax.swing.JSeparator" icon="/com/intellij/uiDesigner/icons/separator.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3" />
-      </item>
-      <item class="javax.swing.JProgressBar" icon="/com/intellij/uiDesigner/icons/progressbar.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1" />
-      </item>
-      <item class="javax.swing.JToolBar" icon="/com/intellij/uiDesigner/icons/toolbar.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1">
-          <preferred-size width="-1" height="20" />
-        </default-constraints>
-      </item>
-      <item class="javax.swing.JToolBar$Separator" icon="/com/intellij/uiDesigner/icons/toolbarSeparator.png" removable="false" auto-create-binding="false" can-attach-label="false">
-        <default-constraints vsize-policy="0" hsize-policy="0" anchor="0" fill="1" />
-      </item>
-      <item class="javax.swing.JScrollBar" icon="/com/intellij/uiDesigner/icons/scrollbar.png" removable="false" auto-create-binding="true" can-attach-label="false">
-        <default-constraints vsize-policy="6" hsize-policy="0" anchor="0" fill="2" />
-      </item>
-    </group>
-  </component>
-</project>
\ No newline at end of file
diff --git a/lesson2/.idea/workspace.xml b/lesson2/.idea/workspace.xml
index 7d22b6a..9d3fc9c 100644
--- a/lesson2/.idea/workspace.xml
+++ b/lesson2/.idea/workspace.xml
@@ -1,9 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ChangeListManager">
-    <list default="true" id="3cf9276a-1775-4e31-91bd-d592b2feede1" name="Default Changelist" comment="">
-      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/JackWang/Sort.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java" afterDir="false" />
+    <list default="true" id="facff19a-521a-4681-9037-09118d33c16b" name="Default Changelist" comment="">
+      <change beforePath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java" afterDir="false" />
     </list>
     <ignored path="$PROJECT_DIR$/.gradle/" />
     <ignored path="$PROJECT_DIR$/build/" />
@@ -14,176 +13,75 @@
     <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
     <option name="LAST_RESOLUTION" value="IGNORE" />
   </component>
-  <component name="CheckStyle-IDEA-workspace">
-    <option name="configuration">
-      <map>
-        <entry key="last-active-plugin-version" value="5.22.1" />
-      </map>
-    </option>
-  </component>
-  <component name="CoverageDataManager">
-    <SUITE FILE_PATH="coverage/lesson2$Sort.ic" NAME="Sort Coverage Results" MODIFIED="1542110989799" SOURCE_PROVIDER="com.intellij.coverage.DefaultCoverageFileProvider" RUNNER="idea" COVERAGE_BY_TEST_ENABLED="false" COVERAGE_TRACING_ENABLED="false">
-      <FILTER>com.cxxt.huangyz0918.lesson.JackWang.*</FILTER>
-    </SUITE>
-  </component>
-  <component name="CoverageViewManager">
-    <option name="myElementSize" value="209" />
-  </component>
   <component name="ExternalProjectsData">
     <projectState path="$PROJECT_DIR$">
       <ProjectState />
     </projectState>
   </component>
-  <component name="ExternalProjectsManager">
-    <system id="GRADLE">
-      <state>
-        <task path="$PROJECT_DIR$">
-          <activation />
-        </task>
-        <projects_view>
-          <tree_state>
-            <expand>
-              <path>
-                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
-                <item name="lesson2" type="f1a62948:ProjectNode" />
-              </path>
-              <path>
-                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
-                <item name="lesson2" type="f1a62948:ProjectNode" />
-                <item name="Tasks" type="e4a08cd1:TasksNode" />
-              </path>
-              <path>
-                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
-                <item name="lesson2" type="f1a62948:ProjectNode" />
-                <item name="Tasks" type="e4a08cd1:TasksNode" />
-                <item name="application" type="c8890929:TasksNode$1" />
-              </path>
-              <path>
-                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
-                <item name="lesson2" type="f1a62948:ProjectNode" />
-                <item name="Tasks" type="e4a08cd1:TasksNode" />
-                <item name="build" type="c8890929:TasksNode$1" />
-              </path>
-            </expand>
-            <select />
-          </tree_state>
-        </projects_view>
-      </state>
-    </system>
-  </component>
   <component name="FUSProjectUsageTrigger">
-    <session id="961781398">
+    <session id="-1484086157">
       <usages-collector id="statistics.lifecycle.project">
         <counts>
-          <entry key="project.closed" value="2" />
-          <entry key="project.open.time.1" value="1" />
-          <entry key="project.open.time.5" value="1" />
-          <entry key="project.opened" value="2" />
+          <entry key="project.open.time.0" value="1" />
+          <entry key="project.opened" value="1" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.extensions.open">
         <counts>
-          <entry key="gradle" value="3" />
           <entry key="java" value="2" />
-          <entry key="xml" value="2" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.types.open">
         <counts>
-          <entry key="Groovy" value="3" />
           <entry key="JAVA" value="2" />
-          <entry key="XML" value="2" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.extensions.edit">
-        <counts>
-          <entry key="gradle" value="140" />
-          <entry key="java" value="86" />
-        </counts>
-      </usages-collector>
-      <usages-collector id="statistics.file.types.edit">
-        <counts>
-          <entry key="Groovy" value="140" />
-          <entry key="JAVA" value="86" />
-        </counts>
-      </usages-collector>
-      <usages-collector id="statistics.js.language.service.starts" />
-      <usages-collector id="statistics.vcs.git.usages" />
-      <usages-collector id="statistics.spring.boot.mvc.usages" />
-      <usages-collector id="statistics.spring.boot.run.usages" />
-    </session>
-    <session id="-311412814">
-      <usages-collector id="statistics.lifecycle.project">
-        <counts>
-          <entry key="project.open.time.3" value="1" />
-          <entry key="project.opened" value="1" />
-        </counts>
-      </usages-collector>
-      <usages-collector id="statistics.file.extensions.open">
         <counts>
           <entry key="java" value="1" />
         </counts>
       </usages-collector>
-      <usages-collector id="statistics.file.types.open">
-        <counts>
-          <entry key="JAVA" value="1" />
-        </counts>
-      </usages-collector>
-      <usages-collector id="statistics.file.extensions.edit">
-        <counts>
-          <entry key="java" value="96" />
-          <entry key="txt" value="10" />
-        </counts>
-      </usages-collector>
       <usages-collector id="statistics.file.types.edit">
         <counts>
-          <entry key="JAVA" value="96" />
-          <entry key="PLAIN_TEXT" value="10" />
+          <entry key="JAVA" value="1" />
         </counts>
       </usages-collector>
     </session>
   </component>
   <component name="FileEditorManager">
-    <leaf SIDE_TABS_SIZE_LIMIT_KEY="300">
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/Two.java">
+    <leaf>
+      <file pinned="false" current-in-tab="true">
+        <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="60">
-              <caret line="3" selection-start-line="3" selection-end-line="6" selection-end-column="3" />
+            <state relative-caret-position="165">
+              <caret line="11" column="11" lean-forward="true" selection-start-line="11" selection-start-column="11" selection-end-line="11" selection-end-column="11" />
             </state>
           </provider>
         </entry>
       </file>
-      <file pinned="false" current-in-tab="true">
+      <file pinned="false" current-in-tab="false">
         <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="260">
-              <caret line="13" column="41" lean-forward="true" selection-start-line="13" selection-start-column="41" selection-end-line="13" selection-end-column="41" />
+            <state>
+              <caret column="45" selection-end-column="45" />
             </state>
           </provider>
         </entry>
       </file>
     </leaf>
   </component>
-  <component name="FileTemplateManagerImpl">
-    <option name="RECENT_TEMPLATES">
-      <list>
-        <option value="Class" />
-      </list>
-    </option>
-  </component>
   <component name="Git.Settings">
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/.." />
   </component>
   <component name="GradleLocalSettings">
     <option name="myGradleHomes">
       <map>
-        <entry key="$PROJECT_DIR$" value="C:\Users\Jack wang\.gradle\wrapper\dists\gradle-4.8-bin\divx0s2uj4thofgytb7gf9fsi\gradle-4.8" />
+        <entry key="$PROJECT_DIR$" value="/usr/local/Cellar/gradle/4.10.2/libexec" />
       </map>
     </option>
     <option name="myGradleVersions">
       <map>
-        <entry key="$PROJECT_DIR$" value="4.8" />
+        <entry key="$PROJECT_DIR$" value="4.10.2" />
       </map>
     </option>
     <option name="availableProjects">
@@ -524,9 +422,7 @@
     </option>
     <option name="modificationStamps">
       <map>
-        <entry key="$USER_HOME$/.gradle/gradle.properties" value="3680958690" />
-        <entry key="$PROJECT_DIR$" value="3084218818110" />
-        <entry key="$PROJECT_DIR$/.gradle" value="0" />
+        <entry key="$PROJECT_DIR$" value="3084234042000" />
         <entry key="$PROJECT_DIR$/build.gradle" value="1036151483" />
       </map>
     </option>
@@ -552,6 +448,88 @@
                 </map>
               </option>
               <option name="name" value="lesson2" />
+              <option name="projectBuildClasspath">
+                <list>
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-native-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-kotlin-dsl-1.0-rc-6.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-wrapper-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-docs-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-jvm-services-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-process-services-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/ant-1.9.11.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/groovy-all-2.4.15.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-build-cache-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-cli-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/ant-launcher-1.9.11.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-api-metadata-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-persistent-cache-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-kotlin-dsl-provider-plugins-1.0-rc-6.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/gradle-kotlin-dsl-tooling-models-1.0-rc-6.jar" />
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+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-diagnostics-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-antlr-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-workers-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-ear-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-signing-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-language-groovy-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-version-control-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-ivy-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/ivy-2.2.0.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-code-quality-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-language-java-4.10.2.jar" />
+                  <option value="/usr/local/Cellar/gradle/4.10.2/libexec/lib/plugins/gradle-announce-4.10.2.jar" />
+                </list>
+              </option>
             </ExternalProjectBuildClasspathPojo>
           </value>
         </entry>
@@ -559,20 +537,15 @@
     </option>
     <option name="projectSyncType">
       <map>
-        <entry key="$USER_HOME$/IdeaProjects/briefcase" value="PREVIEW" />
         <entry key="$PROJECT_DIR$" value="RE_IMPORT" />
+        <entry key="$USER_HOME$/Desktop/Course-PR/lesson2" value="PREVIEW" />
       </map>
     </option>
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   <component name="IdeDocumentHistory">
     <option name="CHANGED_PATHS">
       <list>
-        <option value="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/Lesson/Two.java" />
-        <option value="$PROJECT_DIR$/build.gradle" />
-        <option value="$PROJECT_DIR$/src/test/java/TestA.java" />
-        <option value="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/Two.java" />
-        <option value="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/JackWang/Sort.java" />
-        <option value="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java" />
+        <option value="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java" />
       </list>
     </option>
   </component>
@@ -582,35 +555,17 @@
     <detection-done>true</detection-done>
     <sorting>DEFINITION_ORDER</sorting>
   </component>
-  <component name="ProjectFrameBounds" extendedState="6">
-    <option name="x" value="28" />
-    <option name="y" value="226" />
-    <option name="width" value="1939" />
-    <option name="height" value="1049" />
-  </component>
-  <component name="ProjectInspectionProfilesVisibleTreeState">
-    <entry key="Project Default">
-      <profile-state>
-        <expanded-state>
-          <State />
-        </expanded-state>
-        <selected-state>
-          <State>
-            <id>Android</id>
-          </State>
-        </selected-state>
-      </profile-state>
-    </entry>
-  </component>
-  <component name="ProjectLevelVcsManager" settingsEditedManually="true">
-    <ConfirmationsSetting value="2" id="Add" />
+  <component name="ProjectFrameBounds">
+    <option name="y" value="25" />
+    <option name="width" value="1440" />
+    <option name="height" value="808" />
   </component>
+  <component name="ProjectLevelVcsManager" settingsEditedManually="true" />
   <component name="ProjectView">
     <navigator proportions="" version="1">
       <foldersAlwaysOnTop value="true" />
     </navigator>
     <panes>
-      <pane id="Scope" />
       <pane id="ProjectPane">
         <subPane>
           <expand>
@@ -651,23 +606,23 @@
               <item name="main" type="8a07ba80:GradleTreeStructureProvider$GradleModuleDirectoryNode" />
               <item name="java" type="462c0819:PsiDirectoryNode" />
               <item name="lesson" type="462c0819:PsiDirectoryNode" />
-              <item name="jackwang" type="462c0819:PsiDirectoryNode" />
+              <item name="YajianWang" type="462c0819:PsiDirectoryNode" />
             </path>
           </expand>
           <select />
         </subPane>
       </pane>
       <pane id="PackagesPane" />
+      <pane id="Scope" />
     </panes>
   </component>
   <component name="PropertiesComponent">
     <property name="WebServerToolWindowFactoryState" value="false" />
     <property name="aspect.path.notification.shown" value="true" />
-    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1542111248295" />
-    <property name="last_opened_file_path" value="$PROJECT_DIR$/build.gradle" />
+    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1542118597944" />
     <property name="nodejs_interpreter_path.stuck_in_default_project" value="undefined stuck path" />
     <property name="nodejs_npm_path_reset_for_default_project" value="true" />
-    <property name="settings.editor.selected.configurable" value="preferences.sourceCode.Java" />
+    <property name="settings.editor.selected.configurable" value="preferences.lookFeel" />
   </component>
   <component name="RunDashboard">
     <option name="ruleStates">
@@ -681,13 +636,13 @@
       </list>
     </option>
   </component>
-  <component name="RunManager" selected="Application.Sort">
+  <component name="RunManager">
     <configuration name="Sort" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="com.cxxt.huangyz0918.lesson.jackwang.Sort" />
+      <option name="MAIN_CLASS_NAME" value="com.cxxt.huangyz0918.lesson.YajianWang.Sort" />
       <module name="lesson2_main" />
       <extension name="coverage">
         <pattern>
-          <option name="PATTERN" value="com.cxxt.huangyz0918.lesson.jackwang.*" />
+          <option name="PATTERN" value="com.cxxt.huangyz0918.lesson.YajianWang.*" />
           <option name="ENABLED" value="true" />
         </pattern>
       </extension>
@@ -695,67 +650,9 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
-    <configuration name="Two" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="com.cxxt.huangyz0918.lesson.Two" />
-      <module name="lesson2_main" />
-      <extension name="coverage">
-        <pattern>
-          <option name="PATTERN" value="com.cxxt.huangyz0918.lesson.*" />
-          <option name="ENABLED" value="true" />
-        </pattern>
-      </extension>
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
-    <configuration name="lesson2 [build]" type="GradleRunConfiguration" factoryName="Gradle" temporary="true">
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-        <option name="executionName" />
-        <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="externalSystemIdString" value="GRADLE" />
-        <option name="scriptParameters" />
-        <option name="taskDescriptions">
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-        </option>
-        <option name="taskNames">
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-            <option value="build" />
-          </list>
-        </option>
-        <option name="vmOptions" />
-      </ExternalSystemSettings>
-      <method v="2" />
-    </configuration>
-    <configuration name="lesson2 [run]" type="GradleRunConfiguration" factoryName="Gradle" temporary="true">
-      <ExternalSystemSettings>
-        <option name="executionName" />
-        <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="externalSystemIdString" value="GRADLE" />
-        <option name="scriptParameters" />
-        <option name="taskDescriptions">
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-        </option>
-        <option name="taskNames">
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-        <option name="vmOptions" />
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-      <method v="2" />
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-    <list>
-      <item itemvalue="Application.Two" />
-      <item itemvalue="Gradle.lesson2 [build]" />
-      <item itemvalue="Gradle.lesson2 [run]" />
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     <recent_temporary>
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         <item itemvalue="Application.Sort" />
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-        <item itemvalue="Gradle.lesson2 [build]" />
-        <item itemvalue="Application.Two" />
       </list>
     </recent_temporary>
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@@ -764,72 +661,52 @@
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   <component name="TaskManager">
     <task active="true" id="Default" summary="Default task">
-      <changelist id="3cf9276a-1775-4e31-91bd-d592b2feede1" name="Default Changelist" comment="" />
-      <created>1542093869721</created>
+      <changelist id="facff19a-521a-4681-9037-09118d33c16b" name="Default Changelist" comment="" />
+      <created>1542118231392</created>
       <option name="number" value="Default" />
       <option name="presentableId" value="Default" />
-      <updated>1542093869721</updated>
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-      <option name="presentableId" value="LOCAL-00001" />
-      <option name="project" value="LOCAL" />
-      <updated>1542110182391</updated>
+      <updated>1542118231392</updated>
+      <workItem from="1542118232600" duration="277000" />
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-    <task id="LOCAL-00002" summary="实现了冒泡排序法">
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-      <option name="project" value="LOCAL" />
-      <updated>1542111201115</updated>
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-    <option name="localTasksCounter" value="3" />
     <servers />
   </component>
   <component name="TimeTrackingManager">
-    <option name="totallyTimeSpent" value="7511000" />
+    <option name="totallyTimeSpent" value="277000" />
   </component>
   <component name="ToolWindowManager">
-    <frame x="-7" y="-7" width="1550" height="838" extended-state="6" />
+    <frame x="0" y="25" width="1440" height="808" extended-state="0" />
     <editor active="true" />
     <layout>
-      <window_info content_ui="combo" id="Project" order="0" visible="true" weight="0.18632708" />
+      <window_info id="Designer" />
+      <window_info id="Image Layers" />
+      <window_info id="UI Designer" />
+      <window_info id="Favorites" side_tool="true" />
+      <window_info id="Capture Tool" />
+      <window_info content_ui="combo" id="Project" order="0" visible="true" weight="0.24964234" />
       <window_info id="Structure" order="1" side_tool="true" weight="0.25" />
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-      <window_info id="UI Designer" order="5" />
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-      <window_info id="Capture Tool" order="7" />
+      <window_info anchor="bottom" id="Build" weight="0.32960895" />
+      <window_info anchor="bottom" id="Terminal" />
+      <window_info anchor="bottom" id="Event Log" side_tool="true" />
+      <window_info anchor="bottom" id="Database Changes" show_stripe_button="false" />
+      <window_info anchor="bottom" id="Version Control" show_stripe_button="false" />
+      <window_info anchor="bottom" id="Messages" />
       <window_info anchor="bottom" id="Message" order="0" />
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+      <window_info anchor="bottom" id="Find" order="1" />
+      <window_info active="true" anchor="bottom" id="Run" order="2" visible="true" weight="0.32960895" />
       <window_info anchor="bottom" id="Debug" order="3" weight="0.4" />
       <window_info anchor="bottom" id="Cvs" order="4" weight="0.25" />
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-      <window_info anchor="right" id="Coverage" side_tool="true" weight="0.3297587" />
+      <window_info anchor="right" id="Palette" />
+      <window_info anchor="right" id="Capture Analysis" />
+      <window_info anchor="right" id="Database" />
+      <window_info anchor="right" id="Maven Projects" />
+      <window_info anchor="right" id="Gradle" />
+      <window_info anchor="right" id="Palette&#9;" />
+      <window_info anchor="right" id="Theme Preview" />
       <window_info anchor="right" id="Commander" internal_type="SLIDING" order="0" type="SLIDING" weight="0.4" />
       <window_info anchor="right" id="Ant Build" order="1" weight="0.25" />
       <window_info anchor="right" content_ui="combo" id="Hierarchy" order="2" weight="0.25" />
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   <component name="TypeScriptGeneratedFilesManager">
@@ -838,40 +715,18 @@
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-    <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/Two.java">
+    <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java">
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+          <caret column="45" selection-end-column="45" />
         </state>
       </provider>
     </entry>
-    <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java">
+    <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="260">
-          <caret line="13" column="41" lean-forward="true" selection-start-line="13" selection-start-column="41" selection-end-line="13" selection-end-column="41" />
+        <state relative-caret-position="165">
+          <caret line="11" column="11" lean-forward="true" selection-start-line="11" selection-start-column="11" selection-end-line="11" selection-end-column="11" />
         </state>
       </provider>
     </entry>
@@ -880,7 +735,7 @@
     <states>
       <state key="ProjectJDKs.UI">
         <settings>
-          <last-edited>10</last-edited>
+          <last-edited>1.8</last-edited>
           <splitter-proportions>
             <option name="proportions">
               <list>
diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/compiler.xml b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/compiler.xml
new file mode 100644
index 0000000..de9b81f
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/compiler.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <bytecodeTargetLevel>
+      <module name="lesson" target="" />
+    </bytecodeTargetLevel>
+  </component>
+</project>
\ No newline at end of file
diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/misc.xml b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/misc.xml
new file mode 100644
index 0000000..e208459
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/misc.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/modules.xml b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/modules.xml
new file mode 100644
index 0000000..7e662ae
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/lesson.iml" filepath="$PROJECT_DIR$/lesson.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/vcs.xml b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/vcs.xml
new file mode 100644
index 0000000..07117e4
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/../../../../../../../.." vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/workspace.xml b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/workspace.xml
new file mode 100644
index 0000000..e4789b0
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/.idea/workspace.xml
@@ -0,0 +1,895 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ChangeListManager">
+    <list default="true" id="3cf9276a-1775-4e31-91bd-d592b2feede1" name="Default Changelist" comment="">
+      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/JackWang/Sort.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java" afterDir="false" />
+    </list>
+    <ignored path="$PROJECT_DIR$/.gradle/" />
+    <ignored path="$PROJECT_DIR$/build/" />
+    <ignored path="$PROJECT_DIR$/out/" />
+    <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
+    <option name="SHOW_DIALOG" value="false" />
+    <option name="HIGHLIGHT_CONFLICTS" value="true" />
+    <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
+    <option name="LAST_RESOLUTION" value="IGNORE" />
+  </component>
+  <component name="CheckStyle-IDEA-workspace">
+    <option name="configuration">
+      <map>
+        <entry key="last-active-plugin-version" value="5.22.1" />
+      </map>
+    </option>
+  </component>
+  <component name="CoverageDataManager">
+    <SUITE FILE_PATH="coverage/lesson2$Sort.ic" NAME="Sort Coverage Results" MODIFIED="1542110989799" SOURCE_PROVIDER="com.intellij.coverage.DefaultCoverageFileProvider" RUNNER="idea" COVERAGE_BY_TEST_ENABLED="false" COVERAGE_TRACING_ENABLED="false">
+      <FILTER>com.cxxt.huangyz0918.lesson.JackWang.*</FILTER>
+    </SUITE>
+  </component>
+  <component name="CoverageViewManager">
+    <option name="myElementSize" value="209" />
+  </component>
+  <component name="ExternalProjectsData">
+    <projectState path="$PROJECT_DIR$">
+      <ProjectState />
+    </projectState>
+  </component>
+  <component name="ExternalProjectsManager">
+    <system id="GRADLE">
+      <state>
+        <task path="$PROJECT_DIR$">
+          <activation />
+        </task>
+        <projects_view>
+          <tree_state>
+            <expand>
+              <path>
+                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
+                <item name="lesson2" type="f1a62948:ProjectNode" />
+              </path>
+              <path>
+                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
+                <item name="lesson2" type="f1a62948:ProjectNode" />
+                <item name="Tasks" type="e4a08cd1:TasksNode" />
+              </path>
+              <path>
+                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
+                <item name="lesson2" type="f1a62948:ProjectNode" />
+                <item name="Tasks" type="e4a08cd1:TasksNode" />
+                <item name="application" type="c8890929:TasksNode$1" />
+              </path>
+              <path>
+                <item name="" type="6a2764b6:ExternalProjectsStructure$RootNode" />
+                <item name="lesson2" type="f1a62948:ProjectNode" />
+                <item name="Tasks" type="e4a08cd1:TasksNode" />
+                <item name="build" type="c8890929:TasksNode$1" />
+              </path>
+            </expand>
+            <select />
+          </tree_state>
+        </projects_view>
+      </state>
+    </system>
+  </component>
+  <component name="FUSProjectUsageTrigger">
+    <session id="961781398">
+      <usages-collector id="statistics.lifecycle.project">
+        <counts>
+          <entry key="project.closed" value="2" />
+          <entry key="project.open.time.1" value="1" />
+          <entry key="project.open.time.5" value="1" />
+          <entry key="project.opened" value="2" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.extensions.open">
+        <counts>
+          <entry key="gradle" value="3" />
+          <entry key="java" value="2" />
+          <entry key="xml" value="2" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.types.open">
+        <counts>
+          <entry key="Groovy" value="3" />
+          <entry key="JAVA" value="2" />
+          <entry key="XML" value="2" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.extensions.edit">
+        <counts>
+          <entry key="gradle" value="140" />
+          <entry key="java" value="86" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.types.edit">
+        <counts>
+          <entry key="Groovy" value="140" />
+          <entry key="JAVA" value="86" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.js.language.service.starts" />
+      <usages-collector id="statistics.vcs.git.usages" />
+      <usages-collector id="statistics.spring.boot.mvc.usages" />
+      <usages-collector id="statistics.spring.boot.run.usages" />
+    </session>
+    <session id="-311412814">
+      <usages-collector id="statistics.lifecycle.project">
+        <counts>
+          <entry key="project.open.time.3" value="1" />
+          <entry key="project.opened" value="1" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.extensions.open">
+        <counts>
+          <entry key="java" value="1" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.types.open">
+        <counts>
+          <entry key="JAVA" value="1" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.extensions.edit">
+        <counts>
+          <entry key="java" value="96" />
+          <entry key="txt" value="10" />
+        </counts>
+      </usages-collector>
+      <usages-collector id="statistics.file.types.edit">
+        <counts>
+          <entry key="JAVA" value="96" />
+          <entry key="PLAIN_TEXT" value="10" />
+        </counts>
+      </usages-collector>
+    </session>
+  </component>
+  <component name="FileEditorManager">
+    <leaf SIDE_TABS_SIZE_LIMIT_KEY="300">
+      <file pinned="false" current-in-tab="false">
+        <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/Two.java">
+          <provider selected="true" editor-type-id="text-editor">
+            <state relative-caret-position="60">
+              <caret line="3" selection-start-line="3" selection-end-line="6" selection-end-column="3" />
+            </state>
+          </provider>
+        </entry>
+      </file>
+      <file pinned="false" current-in-tab="true">
+        <entry file="file://$PROJECT_DIR$/src/main/java/com/cxxt/huangyz0918/lesson/jackwang/Sort.java">
+          <provider selected="true" editor-type-id="text-editor">
+            <state relative-caret-position="260">
+              <caret line="13" column="41" lean-forward="true" selection-start-line="13" selection-start-column="41" selection-end-line="13" selection-end-column="41" />
+            </state>
+          </provider>
+        </entry>
+      </file>
+    </leaf>
+  </component>
+  <component name="FileTemplateManagerImpl">
+    <option name="RECENT_TEMPLATES">
+      <list>
+        <option value="Class" />
+      </list>
+    </option>
+  </component>
+  <component name="Git.Settings">
+    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/.." />
+  </component>
+  <component name="GradleLocalSettings">
+    <option name="myGradleHomes">
+      <map>
+        <entry key="$PROJECT_DIR$" value="C:\Users\Jack wang\.gradle\wrapper\dists\gradle-4.8-bin\divx0s2uj4thofgytb7gf9fsi\gradle-4.8" />
+      </map>
+    </option>
+    <option name="myGradleVersions">
+      <map>
+        <entry key="$PROJECT_DIR$" value="4.8" />
+      </map>
+    </option>
+    <option name="availableProjects">
+      <map>
+        <entry>
+          <key>
+            <ExternalProjectPojo>
+              <option name="name" value="lesson2" />
+              <option name="path" value="$PROJECT_DIR$" />
+            </ExternalProjectPojo>
+          </key>
+          <value>
+            <list>
+              <ExternalProjectPojo>
+                <option name="name" value="lesson2" />
+                <option name="path" value="$PROJECT_DIR$" />
+              </ExternalProjectPojo>
+            </list>
+          </value>
+        </entry>
+      </map>
+    </option>
+    <option name="availableTasks">
+      <map>
+        <entry key="$PROJECT_DIR$">
+          <value>
+            <list>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Java class in the current project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createJavaClass" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays the sub-projects of root project 'lesson2'." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="projects" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Exports all the default template files into the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="exportAllTemplates" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="pmd" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Run Checkstyle analysis for test classes" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="checkstyleTest" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Runs this project as a JVM application" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="run" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Generates Gradle wrapper files." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="wrapper" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Exports the default webapp template files into the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="exportWebappTemplates" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Exports the default groovy template files into the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="exportGroovyTemplates" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Initializes a new Gradle Plugin project in the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="initGradlePlugin" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="getHomeDir" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates OS specific scripts to run the project as a JVM application." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="startScripts" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Assembles a jar archive containing the main classes." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="jar" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays the configuration model of root project 'lesson2'. [incubating]" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="model" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="checkstyle" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Processes main resources." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="processResources" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays the tasks runnable from root project 'lesson2'." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="tasks" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Assembles the main distributions" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="assembleDist" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Initializes a new Gradle build." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="init" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Runs the unit tests." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="test" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Compiles main Java source." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="compileJava" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Runs all checks." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="check" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="checkCode" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays all dependencies declared in root project 'lesson2'." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="dependencies" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Processes test resources." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="processTestResources" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Gradle Java project in a new directory named after your project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createJavaProject" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Exports the default scala template files into the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="exportScalaTemplates" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Installs the 'archives' artifacts into the local Maven repository." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="install" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Assembles and tests this project and all projects it depends on." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="buildNeeded" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Bundles the project as a distribution." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="distTar" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Gradle Webapp project in a new directory named after your project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createWebappProject" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Bundles the project as a distribution." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="distZip" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Exports the default java template files into the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="exportJavaTemplates" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Run PMD analysis for main classes" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="pmdMain" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays the components produced by root project 'lesson2'. [incubating]" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="components" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Assembles and tests this project and all projects that depend on it." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="buildDependents" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Assembles main classes." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="classes" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays the dependent components of components in root project 'lesson2'. [incubating]" />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="dependentComponents" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Gradle Groovy project in a new directory named after your project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createGroovyProject" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Gradle Scala project in a new directory named after your project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createScalaProject" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Displays all buildscript dependencies declared in root project 'lesson2'." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="buildEnvironment" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Creates a new Groovy class in the current project." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="createGroovyClass" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
+                <option name="description" value="Initializes a new Gradle Webapp project in the current directory." />
+                <option name="linkedExternalProjectPath" value="$PROJECT_DIR$" />
+                <option name="name" value="initWebappProject" />
+              </ExternalTaskPojo>
+              <ExternalTaskPojo>
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diff --git a/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java
new file mode 100644
index 0000000..8ae02ee
--- /dev/null
+++ b/lesson2/src/main/java/com/cxxt/huangyz0918/lesson/YajianWang/Sort.java
@@ -0,0 +1,28 @@
+package com.cxxt.huangyz0918.lesson.YajianWang;
+
+public class Sort {
+    public Sort() {
+    }
+
+    public static void main(String[] args) {
+//        int[] a = {1, 3, 2, 5, 6, 8, 9, 7};
+//        bubble_sort(a);
+//        for(int i : a) {
+//            System.out.print(i);
+//        }
+
+    }
+
+    public static void bubble_sort(int[] a) {
+        for(int i = 0; i < a.length; ++i) {
+            for(int j = 0; j < a.length - i - 1; ++j) {
+                if (a[j] < a[j + 1]) {
+                    int temp = a[j + 1];
+                    a[j + 1] = a[j];
+                    a[j] = temp;
+                }
+            }
+        }
+
+    }
+}