JFrame 中只显示一个组件 [英] Only one component shows up in JFrame

问题描述

为了改进我的加密项目，我决定制作一个小图形用户界面.但是，当我运行程序时，屏幕上只显示顶部元素，而其他元素似乎被遮挡了，但我无法检查.有谁知道为什么?

除了 e() 和 d() 之外，下面是我的完整代码，因为它们只是加密字符串，与 GUI 无关.我还想要一种在不编辑加密的情况下尽可能加快速度的方法，只是为了使它尽可能好.

As an improvement to my encryption project I decided to make a little GUI. However, when I run the program, only the top element shows up on the screen and it appears to obscure the others, though I have no way of checking. Does anyone know why?

Below is my code in its entirety besides e() and d() because those simply encrypt a string and have nothing to do with a GUI. I would also like a way to speed it up as much as possible without editing the encryption, just to make it as great as possbile.

@SuppressWarnings("serial")
public class EncDecExample extends JFrame implements ActionListener {
    final static JPanel top = new JPanel();
    final static JPanel mid = new JPanel();
    final static JPanel bot = new JPanel();
    final static JTextField in = new JTextField(10);
    final static JTextField out = new JTextField(10);
    final static JButton enc = new JButton("Encrypt");
    final static JButton dec = new JButton("Decrypt");
    final static JFrame f = new JFrame("Encryption/decryption");

    public static void main(String[] args) {
//        EncDec.exampleImplement();

        f.setSize(500, 500);
        f.setResizable(false);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        out.setEditable(false);
        out.setText("Hello");
        in.setVisible(true);
        out.setVisible(true);
        enc.setVisible(true);
        dec.setVisible(true);
        top.add(in);
        mid.add(enc);
        mid.add(dec);
        bot.add(out);
        f.add(top);
        f.add(mid);
        f.add(bot);
        f.setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == enc && !in.getText().equalsIgnoreCase("")) {
            out.setText(EncDec.e(in.getText(), 5));
        }
        else if(e.getSource() == dec && !in.getText().equalsIgnoreCase("")) {
            out.setText(EncDec.d(in.getText()));
        }
    }
}

推荐答案

JFrame 的内容面板有一个 BorderLayout.如果您将一个组件放置在没有约束的 BL 中，它最终会位于 CENTER 中.中心只能显示一个组件.

The content pane of a JFrame has a BorderLayout. If you place a component in a BL with no constraints it ends up in the CENTER. The center can only display one component.

为了立竿见影的效果，我建议:

For an immediate effect, I suggest:

f.add(top, BorderLayout.PAGE_START);
f.add(mid);
f.add(bot, BorderLayout.PAGE_END);

其他要点.

1. 取出f.setSize(500, 500);并在setVisible(true)
之前立即调用pack()
2. 为了更好地结束 GUI，请将 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 更改为 f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
3. in.setVisible(true); 除了框架本身，把这些都去掉.当组件被添加到顶级容器并且该容器本身可见时，它会自动变为可见.
4. 将
   public class EncDecExample extends JFrame
   更改为
   public class EncDecExample
   此代码保留对框架的引用，并且是正确的方法.

1. Take out f.setSize(500, 500); and call pack() immediately before setVisible(true)
2. For a better way to end the GUI, change f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); to f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
3. in.setVisible(true); Except for the frame itself, take these out. A component automatically becomes visible when it is added to a top level container and that container is itself made visible.
4. Change
   public class EncDecExample extends JFrame
   to
   public class EncDecExample
   This code keeps a reference to a frame, and that is the right way to go.

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