emulator & app not working

I have tried everything and I still can't figure it out. I don't think there is problem with the code. when I run the code, its taking too much time to launch the app then showing error : 02/17 23:17:58: Launching app Error while waiting for device: The emulator process for AVD Nexus_5_API_23 was killed.

Then i tried to run on my phone, still not working PLEASE HELP!! package com.example.mac.myapplication;

import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView;

import java.util.Random;

public class MainActivity extends AppCompatActivity { // Declare view variables private TextView mFactTextView; private Button mFactButton; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mFactTextView = (TextView) findViewById(R.id.factTextView); mFactButton = (Button) findViewById(R.id.factButton);

    View.OnClickListener listener = new View.OnClickListener(){
        @Override
        public void onClick(View v){
            String fact = "";
            // randomly select fact
            Random randomGenerator = new Random();
            int randomNumber = randomGenerator.nextInt(3);
            fact = randomNumber +"";
            // update the screen with dynamic fact
            mFactTextView.setText(fact);
          }

    };
    mFactButton.setOnClickListener(listener);

}

}