CODEWITHSUNDEEP
javaeclipseswingjframe
ControlAltDelete
ControlAltDelete

Reputation: 3694

Java Swing window not appearing in Eclipse

I have this code below to display a window using Java Swing. The problem is when I run the code in eclipse the window does not show. When I export the file as an executable JAR file and run it it works. Is there a bug with eclipse that prevents it from running it from there?

What am I missing?

package com.gui;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.BorderLayout;

public class Calculator {

private JFrame frame;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Calculator window = new Calculator();
                window.frame.setVisible(true);
                
                
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public Calculator() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    //frame.setBounds(100, 100, 450, 300);
    frame.setSize(400, 200);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
    JLabel lblNewLabel = new JLabel("Hello World");
    frame.getContentPane().add(lblNewLabel, BorderLayout.NORTH);
    
    
}

}

Upvotes: 0

Views: 3428

Answers (3)

novice_codr
novice_codr

Reputation: 1

Had the same issue and the root cause turned out to be the extra .jar in the build path(using macOS). For me, it worked after removing the org.eclipse.swt.cocoa.macosx.x86_64_3*.jar too. part.

Upvotes: 0

user3062758
user3062758

Reputation: 41

Some projects created by Eclipse/WindowBuilder in macOS have this window-not-showing-up problem.

When an app is created through New > Project > WindowBuilder > SWT Designer > SWT/JFace Java Project, the new project automatically includes several extra jar files in classpath. Certain jar file(s) trigger eclipse to use special arguments (-XstartOnFirstThread) in the command (ps aux | grep to find out) when starting the application, and startOnFirstThread is giving us the problem here. AFAIK, -XstartOnFirstThread is added only in MacOS.

Solution 1: don’t use “WindowBuilder > SWT Designer > SWT/JFace Java Project” to create the project. You can just create a regular java project, and add the stuff you need.

Solution 2: remove the jar files. Right click on project > Properties > Build Path > Configure Build Path > Libraries, remove org.eclipse.swt (removing this one suffices in my case, there might be others in your case).

Upvotes: 1

user4061565
user4061565

Reputation: 545

I had the same problem, and this is what worked for me (after the help of some folks on stackoverflow).

It turns out I had a library problem. I had had imported all the jars in the .lib directory from jfreechart. In reality only two were needed and some unnecessary ones were labeled swt and experimental. Once I removed all the ones that were not needed, did a clean, and rebuilt, everything worked fine.

Oddly, changing the order of the jfreechart library (which included the conflicting jars) to the bottom did not help, the extra jars had to be removed.

Not a jfreechart issue, obviously my own library import issue. So I suggest you try to remove some of the libraries that may be conflicting, then clean, build, and run again. Good luck.

Upvotes: 0

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