Open another application from your own (intent)

    Intent intent = new Intent(Intent.ACTION_MAIN);
    intent.setComponent(ComponentName.unflattenFromString("com.google.android.maps.mytracks/com.google.android.apps.mytracks.MyTracks"));
    intent.addCategory(Intent.CATEGORY_LAUNCHER);
    startActivity(intent);

EDIT :

as suggested in comments, add one line before startActivity(intent);

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

Firstly, the concept of "application" in Android is slightly an extended one.

An application - technically a process - can have multiple activities, services, content providers and/or broadcast listeners. If at least one of them is running, the application is up and running (the process).

So, what you have to identify is how do you want to "start the application".

Ok... here's what you can try out:

1. Create an intent with action=MAIN and category=LAUNCHER
2. Get the PackageManager from the current context using context.getPackageManager
3. packageManager.queryIntentActivity(<intent>, 0) where intent has category=LAUNCHER, action=MAIN or packageManager.resolveActivity(<intent>, 0) to get the first activity with main/launcher
4. Get theActivityInfo you're interested in
5. From the ActivityInfo, get the packageName and name
6. Finally, create another intent with with category=LAUNCHER, action=MAIN, componentName = new ComponentName(packageName, name) and setFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
7. Finally, context.startActivity(newIntent)

I have work it like this,

/** Open another app.
 * @param context current Context, like Activity, App, or Service
 * @param packageName the full package name of the app to open
 * @return true if likely successful, false if unsuccessful
 */
public static boolean openApp(Context context, String packageName) {
    PackageManager manager = context.getPackageManager();
    try {
        Intent i = manager.getLaunchIntentForPackage(packageName);
        if (i == null) {
            return false;
            //throw new ActivityNotFoundException();
        }
        i.addCategory(Intent.CATEGORY_LAUNCHER);
        context.startActivity(i);
        return true;
    } catch (ActivityNotFoundException e) {
        return false;
    }
}

Example usage:

openApp(this, "com.google.android.maps.mytracks");