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

问题描述

作为我加密项目的改进，我决定制作一个小GUI。但是，当我运行程序时，只有顶部元素出现在屏幕上，它似乎模糊了其他元素，尽管我无法检查。有谁知道为什么？


除了 e（）和 d（）因为那些只是加密一个字符串而与GUI无关。我还希望能够在不编辑加密的情况下尽可能加快速度，以使其尽可能好。

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 的内容窗格有 BorderLayout 。如果将组件放在没有约束的BL中，它最终会出现在 CENTER 中。该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.

立即生效，我建议：

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

其他积分。

Other points.



1. 取出 f.setSize（500,500）; 并在<$之前立即拨打 pack（） c $ c> setVisible（true）


2. 要获得更好的结束GUI的方法，请更改 f.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE） ; 到 f.setDefaultCloseOperation（JFrame.DISPOSE_ON_CLOSE）;


3. in。 setVisible（true）; 除了框架本身，取出它们。当一个组件被添加到顶级容器并且该容器本身可见时，该组件自动变为可见。


4. 更改
   公共类EncDecExample扩展JFrame


公共类EncDecExample
   此代码保留对框架的引用，这是正确的方法。

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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