java - 如何自动滚动文本区域而不增加其大小

Question

public void NewMessage(){
JPanel panel = new JPanel();
JLabel label = new JLabel("Enter message:");
JTextArea msgBodyContainer = new JTextArea(10,20);
msgBodyContainer.setAutoscrolls(true);
panel.add(label);
panel.add(msgBodyContainer);


String[] options = new String[]{"OK", "Cancel"};
int option = JOptionPane.showOptionDialog(null, panel, "Message "+searchedProfileFirstName,
                         JOptionPane.NO_OPTION, JOptionPane.PLAIN_MESSAGE,
                         null, options, options[1]);
if(option == 0) // pressing OK button
{

}
    }

这是我在定义的方法 NewMessage() 中使用的代码。我的问题是我想防止这种情况发生: Picture of problem

1-当可见时，文本区域会自动放大并且超出面板边界时不可见2-标签“输入消息”向下移动，与文本区域垂直居中对齐

Answer 1

1. JPanel 默认使用 FlowLayout
2. 像 JTextArea 这样的文本组件确实应该包装在 JScrollPane 中，以允许它们变得比可用空间更大

推荐

• 改用 GridBagLayout，它可以让您更好地控制布局
• 使用 JScrollPane 将 JTextArea 包装在

例如...

    JPanel panel = new JPanel(new GridBagLayout());
    JLabel label = new JLabel("Enter message:");
    JTextArea msgBodyContainer = new JTextArea(10, 20);
    msgBodyContainer.setAutoscrolls(true);
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx = 0;
    gbc.gridy = 0;
    gbc.insets = new Insets(4, 4, 4, 4);
    gbc.anchor = GridBagConstraints.NORTHWEST;
    gbc.fill = GridBagConstraints.HORIZONTAL;
    panel.add(label, gbc);
    gbc.gridx++;
    gbc.fill = GridBagConstraints.BOTH;
    gbc.anchor = GridBagConstraints.NORTHWEST;
    panel.add(new JScrollPane(msgBodyContainer), gbc);

    String[] options = new String[]{"OK", "Cancel"};
    int option = JOptionPane.showOptionDialog(null, panel, "Message ",
                                                                                        JOptionPane.NO_OPTION, JOptionPane.PLAIN_MESSAGE,
                                                                                        null, options, options[1]);

参见:

• How to Use GridBagLayout
• How to Use Scroll Panes

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