in java please thank u

1) why is there an error at line 3 ?

public class Point{

protected int x, y;

public Point(int x, int y ) {

this.x = x; this.y = y ;

}

public String show () {

return "{" + x+" , "+y+"}";

}

}

For the code below

2)First Rewrite Point 3D constructors to assign all three feilds their first values via parameters

3) Then write a code to override the show() method for the Point3D class so that all three feilds are included.

public class Point3D extends Point {

protected int j;

public Point3D(int x, int y, int j){

this.x = x ; this.y = y ; this.j = j ;

}

}