JSON data type

Java is divided into two types of data, one is the basic data type, one is the reference data type;

Basic data types include Byte/short/int/long (4 integers), float/double (2 floating-point types), char (1-character), Boolean (1-Boolean)

Reference data types: Class classes, interface interface, arrays array

There are two types of JSON data: Jsonobject and Jsonarray

• Jsonobject: {key:value,key:value}, where key is a string type, value is an object type, elements are separated by commas, inner key and value are separated by colons, and the outermost is curly braces
  • New Jsonobject:jsonobject obj = new Jsonobject ();
  • Add elements to the Jsonobject object: Obj.put (String key, Object object);
  • Jsonobject Type Conversions
    • From Jsonobjet to String:obj.toString ();
    • From string to JSONObject:JSONObject.parseObject (str);
  • Gets the value of the element from the Jsonobject object: Obj.getter (String key);
• jsonarray:[element 1, Element 2, Element 3 ...], the outermost side is square brackets
  • New Jsonarray object: Jsonarray arr = new Jsonarray ();
  • Convert the String type to jsonarray:string str = "[{\" name\ ": \" Zhang San \ "},1234,12.34]"; Jsonarray arr = Jsonarray.parsearray (str);
  • Add an element to the Jsonarray object: Array.add (object e);
  • Jsonarray Type Conversions
    • The Jsonarray type is converted to String type: arr.tostring ();
    • The string type is converted to Jsonarray type: Jsonarray.parsearray (string str);
  • Extracts the value of an element from a Jsonarray object: array.getter (int index);
  • Traverse Jsonarray:
    • Method One:

      1  for (int i = 0;i < Arr.size (); i++) {2    System.out.println (Arr.get (i));         3 }

    • Method Two: Enhance the For loop

      1  for (Object item:arr) {2    System.out.println (item); 3 }

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JSON data type