Why is nothing showing up in my Java GUI?

问题

I am currently working on a calculator. Right now, I am trying to gain experience with coding Java GUI, by making a simple program that makes a window with a text field. The code can compile without errors, but when I execute the program, the window appears, but without the text field. How do I make the text field visible? The code is shown as follows:

import javax.swing.*;
import java.awt.*;
public class Window {
    public static void main(String[] args) {
    JFrame Window = new JFrame("Window");
        Window.setSize(400,550);
    Window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel Panel = new JPanel (new FlowLayout());
    JTextField TextField = new JTextField("Type something here");
    Window.setVisible(true);
    }
}

回答1:

You haven't added any of the components to your JFrame. You can add them like so:

Panel.add(TextField);
Window.add(Panel);
Window.setVisible(true);

---

Side note: You should stick to the Java naming conventions. Use camel case for variable names.

回答2:

You need to add them before making the frame visible.

Panel.add(TextField);
Window.add(Panel);

回答3:

You need to take the components that you have instantiated (e.g. the Panel and TextField) and add them to appropriate containers.

For example:

Panel.add(TextField);
Window.add(Panel);

If you have not done so already, I would highly recommend visiting http://docs.oracle.com/javase/tutorial/uiswing/index.html for more information on how to use the Swing library.

来源：https://stackoverflow.com/questions/22030127/why-is-nothing-showing-up-in-my-java-gui