when to use this in java code example

Example 1: this obj java meaning

public class Point {
    public int x = 0;
    public int y = 0;
        
    //constructor
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

Example 2: how to use the this keyword in java

class Other{
    public double num;
    public Other(int num){
        this.num = num;
        System.out.println(num);
      	//print 5 to the console
    }
}

class scratch{
    public static void main(String[] args) {
        Other method = new Other(5);
        System.out.println(method.num);
      	//prints 5.0 to the console
    }
}

Example 3: this obj java meaning

public class Point {
    public int x = 0;
    public int y = 0;
        
    //constructor
    public Point(int a, int b) {
        x = a;
        y = b;
    }
}