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import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class BtnColor extends JFrame implements ActionListener {
int count = 0;
JFrame frm = this;
JPanel pan = new JPanel();
JButton btn = new JButton("变色");
public BtnColor(String name) {
super(name);
btn.setBounds(20, 20, 100, 80);
btn.addActionListener(this);
pan.setLayout(null);
pan.add(btn);
frm.add(pan, BorderLayout.CENTER);
frm.setBounds(100, 100, 300, 200);
frm.setDefaultCloseOperation(EXIT_ON_CLOSE);
frm.setVisible(true);
}
// 按钮监听器
public void actionPerformed(ActionEvent e) {
int color = (count++ % 3);
switch (color) {
case 0:
btn.setBackground(Color.RED);
break;
case 1:
btn.setBackground(Color.BLUE);
break;
case 2:
btn.setBackground(Color.GREEN);
break;
}
}
public static void main(String[] args) {
new BtnColor("按钮变色");
}
}