Question

我正在尝试向Panel添加几个JTextFields，JButtons和JLabel，但只显示按钮。我已经为我的JPanel设置了布局为null，并且我为每个项目设置了位置/边界。

frame= new JFrame("Find and Replace");
        JPanel panel = new JPanel(null);
        JLabel findLabel = new JLabel("Find:");
        findLabel.setLocation(0, 20);
        JLabel replaceLabel = new JLabel("Replace with:");
        replaceLabel.setLocation(50, 60);
        findField = new JTextField(20);
        findField.setLocation(30, 100);
        replaceField = new JTextField(20);
        replaceField.setLocation(220, 140);
        replaceAllButton = new JButton("Find and Replace All");
        replaceAllButton.setBounds(20, 200, 100, 25);
        replaceButton = new JButton("Replace");
        replaceButton.setBounds(120, 200, 100, 25);

        panel.add(findLabel);
        panel.add(findField);
        panel.add(replaceLabel);
        panel.add(replaceField);
        panel.add(replaceButton);
        panel.add(replaceAllButton);

Answer 1

您可以在此处使用GridBagLayout而不是使用null布局：

    GridBagConstraints gridBagConstraints;

    panel = new JPanel();
    findLabel = new javax.swing.JLabel();
    findField = new javax.swing.JTextField();
    replaceLabel = new javax.swing.JLabel();
    replaceField = new javax.swing.JTextField();
    replaceAllButton = new javax.swing.JButton();
    replaceButton = new javax.swing.JButton();

    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

    panel.setLayout(new GridBagLayout());

    findLabel.setText("Find :");
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.ipadx = 94;
    gridBagConstraints.ipady = 30;
    panel.add(findLabel, gridBagConstraints);
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.ipadx = 149;
    panel.add(findField, gridBagConstraints);

    replaceLabel.setText("Replace With :");
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.gridx = 0;
    gridBagConstraints.gridy = 1;
    gridBagConstraints.ipadx = 34;
    gridBagConstraints.ipady = 23;
    panel.add(replaceLabel, gridBagConstraints);
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.gridx = 1;
    gridBagConstraints.gridy = 1;
    gridBagConstraints.ipadx = 149;
    panel.add(replaceField, gridBagConstraints);

    replaceAllButton.setText("Find And Replace All");
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.gridx = 0;
    gridBagConstraints.gridy = 2;
    gridBagConstraints.ipady = 9;
    panel.add(replaceAllButton, gridBagConstraints);

    replaceButton.setText("Replace");
    gridBagConstraints = new GridBagConstraints();
    gridBagConstraints.gridx = 1;
    gridBagConstraints.gridy = 2;
    gridBagConstraints.ipadx = 99;
    gridBagConstraints.ipady = 8;
    panel.add(replaceButton, gridBagConstraints);
    //adding panel to the jframe
    getContentPane().add(panel, BorderLayout.CENTER);

    pack();

Answer 2

您已将所有对象添加到面板但忘记添加面板到框架（JFrame的对象）将此行添加到您的代码中 frame.add(panel);

为什么我的JPanel中的某些项目没有显示？

2 个答案: