json4j

The package is for JSON conversion in Java enviroment.

JSON Type	JSON Type Example	Java Type
object	{}	JSONObject
array	[]	JSONArray
string	"example"	String
number	1/1.0	BigInteger/BigDecimal
"true"	true	boolean
"false"	false	boolean
"null"	null	null

Implements

Convert a JSON string into a JSON object

JSON.parse(value) is based on stack structure. There are three stacks in the program, stack stack for characters, class_stack stack for list and dict, keyvalue_stack stack for name/value pair. Scan each character in the string, do the following:

1. If is [, put type/value into class_stack stack
2. If is {, put type/value into the class_stack stack, and put an empty key/value pair (named border) into the keyvalue_stack stack
3. If is,, according to class_stack stack top type (list and dict), list is to operate on the top of the class_stack stack and call its append method, dict is pushed into the keyvalue_stack stack
4. If is ], popping all the elements on the top of the stack stack until it encounters [
5. If is }, pop the keyvalue_stack stack and pop all the elements on the top of the stack until it encounters border
6. If is :, operate on the top of the keyvalue_stack stack and modify the value in the key/value pair
7. Other, put characters into the stack stack

Convert JSON values to JSON strings

JSON.stringify(value) is using recursive method.

1. If it is a basic type in Python (number, string, bool, None), return the corresponding string (1/1.0, "example", true/false, null)
2. If it is list and dict, repeat step 1 for each element in the list and dict
3. Others, It is a class, consider as a dict type, terating over member variables of a class, do the same action as step 1

Installation

<dependency>
  <groupId>com.github.myibu</groupId>
  <artifactId>json4j</artifactId>
  <version>1.0.0</version>
</dependency>

Examples

• Convert a JSON string into a JSON object.

JSONObject jsonObject = JSONObject.parse("[\"foo\", {\"bar\": [\"baz\", null, 1.0, 2, true]}]");
// or write as following if you donot known the type of th json String
Object jo = JSON.parse("[\"foo\", {\"bar\": [\"baz\", null, 1.0, 2, true]}]");

• Convert JSON values to JSON strings.

Map<String,String> map = new HashMap<>();
map.put("1", "00");
String jsonString = JSON.toJSONString(map);

• Format JSON object or JSON strings

Map<String,String> map = new HashMap<>();
map.put("1", "00");
String formatedJsonString = JSON.format(map);