How bulky are extended classes in Java?

Question

I've a class called MapTile that extends JLabel. What I'm doing is loading a JPanel with a lot of MapTile's in a GridLayout. I notice when I load in 100x100 MapTile's the process takes longer than loading in 100x100 JLabel's. This is my MapTile class below.

public class MapTile extends JLabel {
private static final long serialVersionUID = 1L;
private boolean selected;
private Point location;

public MapTile(){
    super();
    location = new Point();
}
public void setLocation(int x, int y){
    setLocation(new Point(x,y));
}
public void setLocation(Point p){
    location = p;
}
public Point getLocation(){
    return location;
}
public void setSelected(Boolean b){
    selected = b;
    if (selected){
        ((GridPanel)this.getParent()).addToSelection(this);
        this.setBorder(BorderFactory.createLineBorder(Color.RED));
    } else {
        this.setBorder(BorderFactory.createLineBorder(Color.BLACK));
    }
    this.repaint();
}
public boolean isSelected(){
    return selected;
}
}

There's nothing fancy, I just overwrote the setLocation method and added a few other methods. I also added just three instance variables.

Does extending a class cause a bunch of extra weight to deal with?

I can't help but think my MapTile class is pretty simple, yet the time between loading 100x100 MapTile's vs loading 100x100 JLabel's is hugely different. It's taking about 4-5 times longer to load MapTile's in large quantities than JLabels.

Answer 1

You did not just overrode the setLocation but you create a new instance of Point each time the setLocation(int,int) method is called which could have a performance impact

Besides that: - have you tested that when you remove the overridden methods you no longer experience a slow-down - have you profiled the application to see where the performance loss occurs

Oh yeah, I do not think your overridden version of setLocation is correct. I fear you must call super.setLocation as well if you want to JLabel to behave correctly