Java-13, static keyword

• In the class, with static member variables declared as static member variables, it is a public variable of the class, are initialized on first use, for all objects of that class who, only a static member variables .
• Static method declared as static method, when the method is called, does not reference the object passed to it, so in a static method can not access non-static members .
  • Is no longer a static method call on an object, it can not access non-static member
• By reference to the object or class name (do not need to instantiate) access static members.

　　

public class Cat {
    private static int sid = 0;
    private String name;
    private int id;
    
    Cat(String name){
        this.name = name;
        id = sid++;
    }
    
    public void info(){
        System.out.println("My name is "+name+" No."+id);
    }
    
    public static void main(String[] args) {
        Cat.sid = 100;
        Cat mimi = new Cat("mimi");
        Cat pipi = new Cat("pipi");
        mimi.info();
        pipi.info();
    }
}

operation result:

My name is mimi No.100
My name is pipi No.101

Memory analysis: