Flip and negate a coordinate point in java? [closed]

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How would you take a point object and flip the coordinates and switch their signs? If you wanted to add a method called flip to the code below:

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

    // flip method goes here

}

I've tried things like:

    public class flip(){
    x = 0-x;
    y = 0-y;
    Point p = new Point(y,x);
}

But it's not working. (81,21) and I only get (-81,-21). It doesn't flip it. But method can't take any parameters, if that's even relevant. Thanks.

Answer 1

If you want to flip the coordinates in place (so calling p.flip() modifies Point p, then this should work:

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

    public void flip() {
        int tmp = x;
        x = -y;
        y = -tmp;
    }
}

If you want the flip() method to return a new point with the coordinates flipped, then you can do this:

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

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

    public Point flip() {
        return new Point(-y, -x);
    }
}

Answer 2

Try this:

public Point flip(Point orig){
    return new Point(-orig.y, -orig.x);
}

If you can not pass it any parameters, make them class variables.

private Point mPoint;

public void flip(){
    mPoint.x = -mPoint.y;
    mPoint.y = -mPoint.x;
}

Answer 3

Something like the following code would work in your situation:

public Point flip(Point point)
{
  return new Point(-point.getY(), -point.getX());
}