帮忙看看代码哪错了.
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
public class ddd extends JPanel{
private JPanel ctrlPanel = new JPanel();
public ddd()
{
this.add(ctrlPanel,BorderLayout.SOUTH);
}
public void setCtrlPanel(JPanel ctrlPanel) {
this.ctrlPanel = ctrlPanel;
}
public JPanel getCtrlPanel()
{
return ctrlPanel;
}
}
class CommonPanel extends JPanel
{
private JButton addBtn = new JButton("添加");
private JButton updateBtn = new JButton("修改");
private JButton delBtn = new JButton("删除");
private JButton cancelBtn = new JButton("取消");
public CommonPanel()
{
add(addBtn);
add(updateBtn);
add(delBtn);
add(cancelBtn);
}
}
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ee extends ddd{
private JButton addBtn = new JButton("添加");
private JButton updateBtn = new JButton("修改");
private JButton delBtn = new JButton("删除");
private JButton cancelBtn = new JButton("取消");
ee()
{
// JPanel p3 = this.getCtrlPanel();
// p3.add(addBtn);
// p3.add(updateBtn);
// p3.add(delBtn);
// p3.add(cancelBtn);
JPanel p3 = new CommonPanel();
this.setCtrlPanel(p3);
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO 自动生成方法存根
JFrame ff = new JFrame();
ff.setSize(500,400);
ee e1 = new ee();
ff.add(e1);
ff.setVisible(true);
}
}
我用setCtrlPanel方法改变了this.ctrlPanel 的引用,为什么界面不会出现那4 个按钮。