private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
for (int i = 0; i < 5; i++){
jPanel1.repaint();
try {
Thread.sleep(500);
}
catch (InterruptedException e){
e.printStackTrace();
}
jPanel1.repaint();
}然后，从JPanel类派生出DrawPanel类，并重写paintComponent方法：
class DrawPanel extends JPanel{
private Color c = null;
protected void paintComponent(Graphics g){
super.paintComponent(g);
if (c == null || c == Color.blue)
c = Color.red;
else
c = Color.blue;
g.setColor(c);
g.fillRect(50, 50, 100, 100);
}
}但是，效果并不是预期的闪烁效果。按下按钮后停顿一段时间没反应，接着颜色仅变化一次。请大家帮忙分析一下这个问题，谢谢！
