My GUI will not display when I hit run in NetBeans

Question

When I select "run" in Netbeans, my GUI does not display. It just displays a box on the bottom of the screen that says "Build successful".

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package modelrange;

import javax.swing.DefaultBoundedRangeModel;

public class RangedModel extends javax.swing.JPanel {

    DefaultBoundedRangeModel myModel;

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new RangedModel().setVisible(true);
            }
       });
    }

    /**
     * Creates new form RangedModel
     */
    public RangedModel() {
        myModel = new DefaultBoundedRangeModel(123, 100, 0, 1000);
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */

    private void initComponents() { 
    This is just the automated netbeans code from the GUI builder (edited out for the post)            
    }

Answer 1

1. JPanel forms are not created with main methods, in GUI Builder, which you do need.

2. JPanel is not a top-level container, which you do need to run a Swing app.

3. A top-level container is, for instance, a JFrame . So you should have created a JFrame form instead of a JPanel form. When you do this in Netbeans GUI Builder, a main method will be provided for you.

4. A simple fix would be just to create a new JFrame form, then just drag and drop the JPanel form to the JFrame form, as seen here , get rid of the main method in your JPanel form, then run the JFrame form class.

5. You may also need to set/change the Main class to the new JFrame form you just created. You can that by looking at this answer

Answer 2

First of all, you are extending JPanel, it's wrong because as peeskillet wrote at points 2 and 3. Kind of top-level container are:

• JFrame : the window with the bar
• JWindow : the window without bar
• JDialog : the window usually used to create option window

So you have to extend one of them, probably the first.

Than in this top-level container you can create JPanel, one or more, everyone will be a container of another object which will be the contenent.

Morover, remember to setVisible every JPanel that you implement and also the top-level container.

Useful links:

• icon in JButton is not shown at the running of the program, what could be?
• Java Swing: multiple windows
• What's the difference between the implements & extends keywords in Java

Answer 3

按照您的java文件所在的路径YourProject / packacge，您可以右键单击您的项目，然后点击那里的“运行文件”。这对我有用。

Answer 4

If you work in NetBeans, after building, check that you are running the file you need from the project. To do this, press shift + f6

Answer 5

change JPanel to JFrame. It will work.