Why do I get NoClassDefFoundError: java/awt/Desktop?

Question

I'm trying to open an URI with Swing that I get above error.

What is the reason and how can I fix it?

When I do it in console everything is OK but when I do in GUI I get this error. I should say that I use Weblogic as server.

Code

private static void open(URI uri) {
    if (Desktop.isDesktopSupported()) {
        try {
            Desktop.getDesktop().browse(uri);
        } catch (IOException e) { /* TODO: error handling */ }
    } else { /* TODO: error handling */ }
}

Stack trace:

Exception in thread "AWT-EventQueue-1" java.lang.NoClassDefFoundError: java/awt/Desktop
at be.azvub.ext.bcfidownloder.BcfiDownloadPanel.open(BcfiDownloadPanel.java:230)
at be.azvub.ext.bcfidownloder.BcfiDownloadPanel.access$000(BcfiDownloadPanel.java:37)
at be.azvub.ext.bcfidownloder.BcfiDownloadPanel$7.actionPerformed(BcfiDownloadPanel.java:147)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:5517)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3129)
at java.awt.Component.processEvent(Component.java:5282)
at java.awt.Container.processEvent(Container.java:1966)
at java.awt.Component.dispatchEventImpl(Component.java:3984)
at java.awt.Container.dispatchEventImpl(Container.java:2024)
at java.awt.Component.dispatchEvent(Component.java:3819)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
at java.awt.Container.dispatchEventImpl(Container.java:2010)
at java.awt.Window.dispatchEventImpl(Window.java:1791)

Answer 1

Doc on NoClassDefFoundError

The searched-for class definition existed when the currently executing class was compiled, but the definition can no longer be found.

You do have some incorrect classloading happening. Mostly due to wrong class loader chaining.

Answer 2

NoClassDefFoundError can only be caused by a classpath problem.

Because Desktop is part of jre, make sure that your classpath contains a reference to the jre library.

In Eclipse, you can go to run configurations --> Classpath and check there

UPDATE:

As Andrew suggested, you can also check you have at least java 1.6

Answer 3

java.awt.Desktop has been introduced in Java 6. Chances are high you're running your code on different JRE versions.