Issue with Opening NetBeans TopComponent at Startup

Question

I'm working on a NetBeans Platform application and I want to open a TopComponent automatically when the application starts. Despite following the typical steps, my TopComponent does not open at startup.

Here are the steps I have followed:

1. Created the TopComponent:

   package com.example.myapp;
   
   import org.openide.windows.TopComponent;
   import org.openide.awt.ActionID;
   import org.openide.awt.ActionReference;
   import org.openide.util.NbBundle.Messages;
   
   @TopComponent.Description(
           preferredID = "MyTopComponent",
           persistenceType = TopComponent.PERSISTENCE_ALWAYS
   )
   @TopComponent.Registration(
           mode = "editor",
           openAtStartup = false // I handle the opening manually
   )
   @ActionID(category = "Window", id = "com.example.myapp.MyTopComponent")
   @ActionReference(path = "Menu/Window", position = 0)
   @Messages({
       "CTL_MyTopComponent=My TopComponent",
       "HINT_MyTopComponent=This is a MyTopComponent window"
   })
   public final class MyTopComponent extends TopComponent {
   
       public MyTopComponent() {
           initComponents();
           setName(Bundle.CTL_MyTopComponent());
           setToolTipText(Bundle.HINT_MyTopComponent());
       }
   
       private void initComponents() {
           // Initialize your components here
       }
   
       public static synchronized MyTopComponent getInstance() {
           MyTopComponent instance = (MyTopComponent) WindowManager.getDefault().findTopComponent("MyTopComponent");
           if (instance == null) {
               instance = new MyTopComponent();
           }
           return instance;
       }
   } 
   
   

2. Created an Installer class to handle the startup logic:

package com.example.myapp;

import org.openide.modules.ModuleInstall;
import org.openide.windows.WindowManager;

public class Installer extends ModuleInstall {

    @Override
    public void restored() {
        WindowManager.getDefault().invokeWhenUIReady(() -> {
            MyTopComponent tc = MyTopComponent.getInstance();
            if (tc != null) {
                tc.open();
                tc.requestActive();
            }
        });
    }
}

3. Registered the Installer class in the manifest.mf file:

Manifest-Version: 1.0
OpenIDE-Module: com.example.myapp
OpenIDE-Module-Specification-Version: 1.0
OpenIDE-Module-Install: com/example/myapp/Installer.class

Despite following these steps, the TopComponent does not open at startup. Here are additional details and steps I've taken to debug the issue:

• Verified that the Installer class is correctly placed in the specified package.
• Checked NetBeans logs for any errors or warnings related to the TopComponent or Installer (none found).
• Cleaned and rebuilt the module.
• Tried running the module in a clean NetBeans user directory.

What could be causing the TopComponent to not open at startup, and how can I resolve this issue?

Any help or suggestions would be greatly appreciated.

Answer 1

Using ModuleInstall/restored() is probably too early, Netbeans UI is not ready yet.

Instead, try the same with @onShowing, so that your code is called when UI is ready:

@onShowing
public class OpenStart implements Runnable {

    @Override
    public void run() {
        WindowManager.getDefault().invokeWhenUIReady(() -> {
            MyTopComponent tc = MyTopComponent.getInstance();
            if (tc != null) {
                tc.open();
                tc.requestActive();
            }
        });
    }
}