在调用this()之前在重载的构造函数中执行代码

public class MyClass {
    private int x;
    private int y;

    public MyClass() {
        this(0, 0);
    }

    public MyClass(int x) {
        this(x, 0);
    }

    public MyClass(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

public class MyClass {
    private int x;
    private int y;

    public MyClass() : this(0, 0) {
    }

    public MyClass(int x) : this(x, 0) {
    }

    public MyClass(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

class MyClass:
    def __init__(self, x=0, y=0):
        self.x = x
        self.y = y