WhiteBlack

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class WhiteBlack {
  private final JFrame f;
  private final Container c;
  private final JPanel p;
  private final JButton b;
  private boolean white;

  public WhiteBlack() {
    f = new JFrame("WHITE AND BLACK");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(200, 40);
    f.setLocationRelativeTo(null);
    c = f.getContentPane();
    p = new JPanel();
    b = new JButton(" PUSH ");
    b.setBackground(Color.white);
    white = true;
    b.addMouseListener(new MouseAdapter() {
      @Override
      public void mouseClicked(MouseEvent e) {
        if (white) {
          b.setBackground(Color.black);
          white = false;
          return;
        }
        b.setBackground(Color.white);
        white = true;
      }
    });
    p.add(b);
    c.add(p, BorderLayout.CENTER);
    f.setVisible(true);
  }

  public static void main(String[] args) {
    new WhiteBlack();
  }
}