The method getSystemService(String) is undefined for the type Listen

I'm trying to check if com.android.music is running and I'm getting the following error on this line this.getSystemService(Context.ACTIVITY_SERVICE);

error:

The method getSystemService(String) is undefined for the type Listen

Code:

public boolean isMusicRunning() {        
    ActivityManager activityManager = (ActivityManager) this.getSystemService(Context.ACTIVITY_SERVICE);
    List<RunningAppProcessInfo> procInfos = activityManager.getRunningAppProcesses();
    for (int i = 0; i < procInfos.size(); i++) {
        if (procInfos.get(i).processName.equals("com.android.music")) {
            Toast.makeText(null, "music is running",
                    Toast.LENGTH_LONG).show();
        }
    }
}

If you could let me know what I'm doing wrong here that would be great!