我希望所有按钮的尺寸都相同。带有文本“打开保存”的那个是最宽的，所以我想使用那个作为调整其他按钮大小的度量。但是，当程序中包含以下代码行时，该按钮将不会显示：newButton.setPreferredSize（openSaveButton.getSize（））;
这是到目前为止的完整程序：
public class Project1 implements ActionListener {
// The frames
private JFrame mainMenu = new JFrame("Main Menu");
private JPanel mainPanel = new JPanel();
private JFrame game = new JFrame("Game");
private JPanel gamePanel = new JPanel();
// Controls
private JButton newButton = new JButton("New");
private JButton openSaveButton = new JButton("Open Save");
private JButton exitButton = new JButton("Exit");
private JTextArea textArea = new JTextArea();
public static void main(String[] args) {
new Project1();
}
// Constructors
public Project1() {
mainPanel.setLayout(new GridBagLayout());
addItem(mainPanel, newButton, 0, 0, 1, 1, GridBagConstraints.CENTER);
newButton.addActionListener(this);
newButton.setPreferredSize(openSaveButton.getSize());
addItem(mainPanel, openSaveButton, 0, 1, 1, 1, GridBagConstraints.CENTER);
openSaveButton.addActionListener(this);
addItem(mainPanel, exitButton, 0, 2, 1, 1, GridBagConstraints.CENTER);
exitButton.addActionListener(this);
mainMenu.add(mainPanel, BorderLayout.NORTH);
openFrame(mainMenu, 10, 10, JFrame.EXIT_ON_CLOSE);
gamePanel.setLayout(new GridBagLayout());
addItem(gamePanel, textArea, 0, 0, 1, 1, GridBagConstraints.CENTER);
openFrame(game, 200, 10, JFrame.DO_NOTHING_ON_CLOSE);
}
// Setters
// Getters
// ActionListener override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == newButton) {
newGame();
} else if (e.getSource() == openSaveButton) {
openFile();
} else if (e.getSource() == exitButton) {
System.exit(0);
}
}
// Other functions and procedures
private void openFrame(JFrame what, int x, int y, int operation) {
what.pack();
what.setLocation(x, y);
what.setVisible(true);
what.setResizable(false);
what.setDefaultCloseOperation(operation);
}
private void addItem(JPanel p, JComponent c, int x, int y, int width, int height,
int align) {
GridBagConstraints gc = new GridBagConstraints();
gc.gridx = x;
gc.gridy = y;
gc.gridwidth = width;
gc.gridheight = height;
gc.weightx = 100.0;
gc.weighty = 100.0;
gc.insets = new Insets(5, 5, 5, 5);
gc.anchor = align;
gc.fill = GridBagConstraints.NONE;
p.add(c, gc);
}
private void newGame() {
}
private void openFile() {
}
}
以下是发生的情况的两个屏幕截图，没有一行，带有：
最佳答案
但是，当程序中包含以下代码行时，该按钮将不会显示：newButton.setPreferredSize（openSaveButton.getSize（））;
然后，不要这样做。
当您调用openSaveButton.getSize()时，openSaveButton没有大小，它是0x0，所以现在您告诉布局管理器newButton应该具有首选的大小0x0，这是我们很好地应用的，现在您按一下不再可见。
现在，如果我对您要执行的操作正确无误，请尝试在gc.fill = GridBagConstraints.NONE;方法中将gc.fill = GridBagConstraints.HORIZONTAL;更改为addItem。
有关更多详细信息，请参见How to Use GridBagLayout
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