Android: How do I use activities provided from other apps?

I'd like to use activities that are not bundled with my app. How could I do that? Using intents or something? I am sure it must be simple.

UPDATE

The main problem is that I can't actually do this:

new Intent(this, SomeExternalActivity.class))

because I can't import the class (it's an external app). Something similar, using a string or something.

Thanks a lot!

UPDATE

This one doesn't work开发者_如何学编程 either:

new Intent(this, Class.forName("com.somepackage.SomeExternalActivity");

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You can only start activities bundled with your app with this constructor:

Intent(Context packageContext, Class<?> cls)

You will need to use one of the following to access an external activity:

Intent(String action)
Intent(String action, Uri uri)

In your case you would use this intent:

new Intent("com.somepackage.SomeExternalActivity");

Also note that to access an activity in another app, that app needs to give access to it's activity (through AndroidManifest.xml)

Check the following for more explanation: http://developer.android.com/reference/android/content/Intent.html http://developer.android.com/guide/topics/manifest/manifest-intro.html http://developer.android.com/guide/topics/intents/intents-filters.html

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This is a working example, for the RemoteDroid

Intent intent = new Intent(Intent.ACTION_MAIN); 
intent.setClassName("com.joshsera", "com.joshsera.RemoteDroid"); 
startActivity(intent); 

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The activity you are calling should appear not only in the Manifest for its own package, but in the Manifest for the CALLING package, too.