main, add missing or deleted import.

app/src/main/java/com/hyperling/apps/infinitetimer/MainActivity.java

@@ -5,6 +5,7 @@ import android.content.DialogInterface;
 import android.content.SharedPreferences;
 import android.graphics.Color;
 import android.media.AudioManager;
+import android.media.MediaPlayer;
 import android.media.Ringtone;
 import android.media.RingtoneManager;
 import android.net.Uri;