Packaging

The reason for the introduction of packaging

We all know java It's pure object-oriented programming , But it contains 8 Basic data type in , They are used to create objects , Therefore, the packaging class is introduced , Corresponding to eight basic data types , The following are the packaging classes corresponding to the eight basic types .

1. byte -->Byte
2. char -->Character
3. short -->Short
4. int -->Integer
5. float -->Float
6. double -->Double
7. long -->Long
8. boolean -->Boolean

Methods of packaging class

9. Manual packing box ： Corresponding packaging .valueof(data);

Integer integer = Integer.valueOf(100);
Character character =Character.valueOf('c');

10. Manual unpacking ：

int num =integer.intValue();
char ch = character.charvalue();

Here, I'll just list these two , Other types can be used as above , In addition to using the methods provided by the packaging class to pack and unpack ,java It also provides us with automatic packing and unpacking mechanism .

Automatic packing and unpacking

1. Automatic packing box

Integer integer2 =12;

2. Automatic dismantling

int num2 = integer;

Test the code written by yourself

public class PInteger {
    
	
	public static void main(String[] args) {
    
		
		// Manual packing box -->> Corresponding packaging .valueOf( Package data );
		Integer integer = Integer.valueOf(100);
		Character character =Character.valueOf('c');
		System.out.println(" After packing box ："+integer);
		System.out.println(" After packing box ："+character);
		
//  Manual unpacking -->> Wrapper class object .valueof();
		int num =integer.intValue();
		char ch =character.charValue();
		System.out.println(" After unpacking ："+num);
		System.out.println(" After unpacking ："+ch);
		
//  Automatic packing box 
		Integer integer2 =12;
		Character character2 = 'a';
		System.out.println(" After automatic packing ："+integer2);
		System.out.println(" After automatic packing ："+character2);
		
//  Automatic dismantling 
		int num2 = integer;
		char ch2 =character;
		System.out.println(" After automatic unpacking ："+num2);
		System.out.println(" After automatic unpacking ："+ch2);
	}
}

Tips

The above is just my own opinion , If the same is purely accidental . If there is a mistake , Please understand , Don't spray ！ If there is gain or doubt , Comments are welcome on thumb up ！