java - 为什么从菜单栏中删除组件不起作用？

Question

我正在尝试从框架中删除一个元素。但我的代码似乎不起作用。

在构造函数中，如果flag为true，那么我必须删除菜单部分“Advanced”。但以下代码不起作用。这有什么问题吗？

package test;

public class TestFrame extends javax.swing.JFrame {
    public TestFrame(boolean flag) {
        initComponents();
        if(flag) remove(jMenuAdvanced);
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        jMenuAdvanced = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenuItem2 = new javax.swing.JMenuItem();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jTextField1.setText("Any Text");

        jButton1.setText("OK");

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(138, 138, 138)
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 262, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(246, 246, 246)
                        .addComponent(jButton1)))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(129, 129, 129)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(69, 69, 69)
                .addComponent(jButton1)
                .addContainerGap(94, Short.MAX_VALUE))
        );

        jLabel1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        jLabel1.setText("Sample Frame");

        jMenu1.setText("File");
        jMenuBar1.add(jMenu1);

        jMenuAdvanced.setText("Advanced");

        jMenuItem1.setText("Advanced work 1");
        jMenuAdvanced.add(jMenuItem1);

        jMenuItem2.setText("Advanced work 2");
        jMenuAdvanced.add(jMenuItem2);

        jMenuBar1.add(jMenuAdvanced);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(199, 199, 199)
                .addComponent(jLabel1)
                .addContainerGap(180, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

        pack();
    }// </editor-fold>                        

    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenuAdvanced;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItem2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JTextField jTextField1;                 
}

Answer 1

在生成的代码中，请注意 Neatbeans 在 jMenuBar1 中添加了 jMenuAdvanced。因此，要删除它，您必须从同一组件而不是框架中删除。构造函数的第二行如下所示:

if(flag) jMenuBar1.remove(jMenuAdvanced);