How to extend JTextField to generate a defined response to focusgain

Question

I suspect this is a pretty trivial question. I wish to create a component MyTextField which extends JTextField; The component should respond to gaining focus by changing color and respond to losing focus by changing to one of two colors depending on whether entry is valid. How to do?

Answer 1

You can make your MyTextField class extend JTextField and implement FocusListener

Option# 1

public class MyTextField extends JTextField implements FocusListener  {
    public MyTextField (){
        addFocusListener(this);
    }

    @Override
    public void focusGained(FocusEvent event) {

    }

    @Override
    public void focusLost(FocusEvent event) {

    }
}

Option# 2

public class MyTextField extends JTextField {
public MyTextField (){
    addFocusListener(new FocusListener() {
            @Override
            public void focusLost(FocusEvent arg0) {
            }

            @Override
            public void focusGained(FocusEvent arg0) {
            }
        });
}
}