Indicates whether the specified action can be used as an intent - #android http://www.curious-creature.org/2008/12/15/android-can-i-use-this-intent/

intent_available.java

/**
 * Indicates whether the specified action can be used as an intent. This
 * method queries the package manager for installed packages that can
 * respond to an intent with the specified action. If no suitable package is
 * found, this method returns false.
 *
 * @param context The application's environment.
 * @param action The Intent action to check for availability.
 *
 * @return True if an Intent with the specified action can be sent and
 *         responded to, false otherwise.
 */
public static boolean isIntentAvailable(Context context, String action) {
    final PackageManager packageManager = context.getPackageManager();
    final Intent intent = new Intent(action);
    List list =
            packageManager.queryIntentActivities(intent,
                    PackageManager.MATCH_DEFAULT_ONLY);
    return list.size() > 0;
}