Application Crashes When Moving From One View To Another

So I've been working on a music player in android studio and I've created two java classes. One for Main Start Screen(StartScreen.Java) and one for the main player (player.Java). I have an onClicl event associated with a button as shown below.

public void onclick(View view) {
Intent detailIntent = new Intent(this, main_player.class);
startActivity(detailIntent);
}

The code for the second Java Class is as below. There is nothing in the java class as for now.

package com.example.musicplayer.app;
import android.app.Activity;
import android.os.Bundle;
public class main_player extends Activity {
protected void onCreate(Bundle savedInstanceState) {

[Code] .....

Where is the actual mistake because the app works fine until i click the button that is suppose to take me to the main player screen?