Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Main extends JFrame {

    JComboBox<String> box = new JComboBox<String>(new String[] { "1", "22", "33" });

    public Main() {
        box.setBackground(Color.RED);
        box.addFocusListener(getFocusListener());
        JTextField f = new JTextField();
        add(box, BorderLayout.SOUTH);
        add(f, BorderLayout.NORTH);
        pack();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    private FocusListener getFocusListener() {
        return new FocusAdapter() {
            @Override
            public void focusGained(FocusEvent arg0) {
                super.focusGained(arg0);
                box.setBackground(Color.BLUE);
                validate();
            }

            @Override
            public void focusLost(FocusEvent arg0) {
                super.focusLost(arg0);
                box.setBackground(Color.red);
                validate();
            }
        };
    }

    public static void main(String... s) {
        new Main();
    }
}