NetBeans 如何向panel里动态添加控件？

Question

    private void jButton2MouseClicked(java.awt.event.MouseEvent evt) {
        javax.swing.JButton jbuttonx = new javax.swing.JButton();
        jbuttonx.setText("test");
        jbuttonx.setName("jButtonx");
        
        mainPanel.add(jbuttonx);
    }比如我想按一下按钮，在Panel中再生成一个按钮控件，如上写该按钮不显示，请教一下该如何完善

Answer 1

是呀，啥layout呀javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(37, 37, 37)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)

Answer 2

public class Test extends JFrame implements ActionListener{

public Test(){
this.setSize(200, 200);
this.setLocation(200,200);
this.setLayout(new GridLayout(3,3));

JButton btn1 = null;
btn1 = new JButton("添加按钮");
btn1.addActionListener(this);
this.getContentPane().add(btn1);

this.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String[] args) { JFrame frame = new Test();
frame.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
JButton btn2 = new JButton("新按钮");
this.getContentPane().add(btn2);

                //为什么没有下面两句话就没有新按钮出现呢？
                btn2.setVisible(false);
btn2.setVisible(true);

}
}
本来想帮楼主解决问题的 但是现在自己出问题了。我是在Eclipse中测试的。希望高手解答。

Answer 3

 private void jButton2MouseClicked(java.awt.event.MouseEvent evt) { 
        javax.swing.JButton jbuttonx = new javax.swing.JButton(); 
        jbuttonx.setText("test"); 
        jbuttonx.setName("jButtonx"); 
        
        mainPanel.add(jbuttonx); 
        mainPanel.revalidate();//加入这句话
 }
调用revalidate()更新一下，就可以显示了

Answer 4

谢谢楼上几位回答，我测试了一下，还是没加layout的问题，如下即可显示了
    private void jButton2MouseClicked(java.awt.event.MouseEvent evt) {                                      
        // TODO add your handling code here:
        javax.swing.JButton jbuttonx = new javax.swing.JButton();
        jbuttonx.setText("test");
        jbuttonx.setName("jButtonx");        javax.swing.GroupLayout mainPanelLayouttest = new javax.swing.GroupLayout(mainPanel);
        mainPanel.setLayout(mainPanelLayouttest);
        mainPanelLayouttest.setHorizontalGroup(
            mainPanelLayouttest.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(mainPanelLayouttest.createSequentialGroup()
                .addGroup(mainPanelLayouttest.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(mainPanelLayouttest.createSequentialGroup()
                        .addGap(280, 280, 280)
                        .addComponent(jbuttonx, javax.swing.GroupLayout.PREFERRED_SIZE , 160, javax.swing.GroupLayout.PREFERRED_SIZE)))
                        
                .addContainerGap(80, Short.MAX_VALUE))
        );        mainPanelLayouttest.setVerticalGroup(
            mainPanelLayouttest.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(mainPanelLayouttest.createSequentialGroup()
                .addGap(61, 61, 61)
                .addComponent(jbuttonx))                
        );
    }