Four steps of anonymous object encapsulation this

Anonymous object: When creating an object, no variable is used to save the address in the heap
eg: new student();
Usage scenario: It
can only be used directly when it is created, and can only be used once.
eg: start thread: new Thread().start();
Function:
can save resources, because GC will recycle anonymous objects from time to time.
(GC is a garbage collection mechanism, the main object of recycling is anonymous objects)

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Four steps of encapsulation:

1. Private member variables (modify member variables with private)
2. Provide getXxx() and void setXxx(...) methods for each member variable. If the current member variable type is boolean type, change getXxx() to isXxx()
3. No-parameter construct
4. This class is decorated with public

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The main two functions of this
1. Solve the ambiguity between member variables and local variables

public void setName(String name) {
    
    
		this.name = name;//直接从成员变量位置找name
		//name=name//这里就近原则，第一个name就是参数name，打印为null
	}

2. Reuse other construction methods to simplify the code for assigning member variables

public User(String name, String phone) {
    
    
		super();
		this.name = name;
		this.phone = phone;
	}
	
public User(String name, String phone, boolean vip) {
    
    
	this(name,phone);
	this.vip = vip;
}

Extension: Fields have default values, such as the initial password of the account.
Entity class

public User(String name) {
    
    
		this(name,"123456");
	}
	
public User(String name, String pwd) {
    
    
	this.name=name;
	this.pwd = pwd;
}

Test class

public class UserTest {
    
    

	public static void main(String[] args) {
    
    
		//通过有参构造进行赋值，初始账户密码均为123456
		User shp=new User("小明");
		User shp=new User("小红");
		User shp=new User("小花");
	}
}

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When creating an object, the bytecode file of this class will be loaded into the memory area
of the metaspace ; the created object is in the heap, and the corresponding variable of the method in the stack frame stores the address of the object