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this and super in java

I’m new to development. Something that I’m still unable to understand is the difference between this and super keywords. If there are any answers, it would be highly appreciated. Thanks.

Answer 1

In Java the keyword this refers to the current object of a class, like in:

class Point {
    public int x = 0;
    public int y = 0;

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

    public String toString() {
       return x + "," + y;
    }
}


class Point3D extends Point {
    public int z = 0;

    public Point(int x, int y, int z) {
        super(x,y);
        this.z = z;
    }

    public String toString() {
       return super.toString() + "," + z;
    }
}

In the constructor of the class Point this.x refers to the x defined in the class, where x is the parameter passed into the constructor. Here this is used to resolve the ambiguity of the name x. The same thing is true for y.

In the class Point3D the method toString() uses the return value of the super class Point to produce its own return value.