Q: App crashes when start a new intent Its been a while since I made an app. So I may be forgetting something. Whenever I press a button to start another intent, the app crashes. Is there something I'm missing?
 public class MainActivity extends Activity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        Button playButton = findViewById(R.id.play_button);
        playButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                Intent play = new Intent(MainActivity.this, PointsActivity.class);
                startActivity(play);
            }
        });

        Button leaderButton = findViewById(R.id.leader_board);
        leaderButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                Intent leader = new Intent(MainActivity.this, LeaderBoard.class);
                startActivity(leader);
            }
        });


    }


}


A: Look like you are not declaring your next activity in AndroidMainfest.xml
<manifest ... >
  <application ... >
      <activity android:name=".PointsActivity" />
      <activity android:name=".LeaderBoard" />
      ...
  </application ... >
  ...
</manifest >


A: Without your stacktrace it is impossible to know what your error is, are you getting invalid casting exceptions? Usually you need to cast widgets into objects before assigning them to variables Ie your line 
Button playButton = findViewById(R.id.playbutton);
should be 
Button playButton = (Button)findViewById(R.id.playbutton);
notice the explicit cast to Button, you may be getting errors like cannot cast android.widget.button to button, this will fix those.
