just read a simple Oracle manual:
https://docs.oracle.com/javase/tutorial/java/javaOO/thiskey.html or read stackoverflow.com more carefulread stackoverflow.com more careful
public class Rectangle { private int x, y; private int width, height; public Rectangle() { this(0, 0, 1, 1); } public Rectangle(int width, int height) { this(0, 0, width, height); } public Rectangle(int x, int y, int width, int height) { this.x = x; this.y = y; this.width = width; this.height = height; } ... }