Question

我在Eclipse中创建了一个带有标签的简单Java JFrame，带有2个文本字段的2个单选按钮和一个JButton。当我运行程序时，它内部的对象混乱，按钮和文本字段不显示，有时文本字段占据框架的整个大小。但是，当我最小化/最大化帧然后恢复它时，它们正常工作。这是代码：

   import java.awt.BorderLayout;
   import java.awt.Dimension;
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;
   import java.awt.event.WindowAdapter;
   import java.awt.event.WindowEvent;

   import javax.swing.BorderFactory;
   import javax.swing.Box;
   import javax.swing.BoxLayout;
   import javax.swing.JButton;
   import javax.swing.JFrame;
   import javax.swing.JLabel;
   import javax.swing.JPanel;
   import javax.swing.JRadioButton;
   import javax.swing.JTextField;

   public class myframe {

   public static void main(String s[]) {
    JFrame frame = new JFrame("Title");
    frame.addWindowListener(new WindowAdapter() {

        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    });
    // This is an empty content area in the frame
    JLabel jlbempty = new JLabel("");
    jlbempty.setPreferredSize(new Dimension(500, 400));
    frame.getContentPane().add(jlbempty, BorderLayout.CENTER);
    frame.pack();
    frame.setVisible(true); 
    frame.setBounds(0, 0, 500, 400);

JPanel panel = new JPanel();
frame.getContentPane().add(panel, BorderLayout.NORTH);
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.add(Box.createRigidArea(new Dimension(0,5)));
panel.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

JLabel label = new JLabel("My label");
panel.add(label);

JPanel buttonPane = new JPanel();
frame.add(buttonPane);
buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS));
buttonPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
JRadioButton cb = new JRadioButton("1");
buttonPane.add(cb);
JTextField tf = new JTextField(0);
tf.setText("");
buttonPane.add(tf);

JPanel panel3 = new JPanel();
frame.add(panel3);
panel3.setLayout(new BoxLayout(panel3, BoxLayout.LINE_AXIS));
panel3.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
JRadioButton cb2 = new JRadioButton("2");
panel3.add(cb2);
JTextField tf2 = new JTextField(0);
tf.setText("");
panel3.add(tf2);


JPanel panel2 = new JPanel();
JButton button = new JButton("click me");
frame.add(panel2);
panel2.add(button);
button.addActionListener(new Action());

panel.add(buttonPane);
panel.add(panel3);
panel.add(panel2);
    }

static class Action implements ActionListener{

    public void actionPerformed(ActionEvent arg0) {
        JFrame frame2 = new JFrame("Clicked");
        frame2.setVisible(true);
        frame2.setSize(100, 200);
        JLabel label2 = new JLabel("You clicked me");
        JPanel panel2 = new JPanel();
        frame2.add(panel2);
        frame2.add(label2);

    }

}
}

Answer 1

在您的主要方法中，您需要在最后执行此操作：

frame.pack();
frame.setVisible(true);

Answer 2

在添加所有组件后，您应该再次调用frame.pack();，以便所有容器元素都可以调整大小以最适合其组件。

http://docs.oracle.com/javase/7/docs/api/java/awt/Window.html#pack()

您还应该在最后调用frame.SetVisible(true);，因此只显示所有组件已加载的表单（否则您可以在加载时看到黑框）。

Java：JFrame中的对象搞砸了

2 个答案: