MainActivity.java

package com.example.ragie.sampleactivitytofragment;

import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
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 Main2Activity extends AppCompatActivity {


    Button answer1, answer2, answer3, answer4;
    TextView score, question;

    private Question mQuestion = new Question();
    private String mAnswer;
    private int mScore = 0;
    private int mQuestionLength = mQuestion.mQuestion.length;

    Random r;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        r = new Random();

        answer1 = (Button) findViewById(R.id.answer1);
        answer2 = (Button) findViewById(R.id.answer2);
        answer3 = (Button) findViewById(R.id.answer3);
        answer4 = (Button) findViewById(R.id.answer4);

        score = (TextView) findViewById(R.id.score);
        question = (TextView) findViewById(R.id.question);
        score.setText("Score:" + mScore);

        updateQuestion(r.nextInt(mQuestionLength));

        answer1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (answer1.getText() ==mAnswer){
                    mScore++;
                    score.setText("Score:" + mScore);
                    updateQuestion(r.nextInt(mQuestionLength));

                }else {

                    gameOver();
            }

            }
        });

        answer2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (answer2.getText() ==mAnswer){
                    mScore++;
                    score.setText("Score:" + mScore);
                    updateQuestion(r.nextInt(mQuestionLength));

                }else {

                    gameOver();

            }

            }
        });

        answer3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (answer3.getText() ==mAnswer){
                    mScore++;
                    score.setText("Score:" + mScore);
                    updateQuestion(r.nextInt(mQuestionLength));

                }else {
                    gameOver();


                }

            }
        });

        answer4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (answer4.getText() ==mAnswer){
                    mScore++;
                    score.setText("Score:" + mScore);
                    updateQuestion(r.nextInt(mQuestionLength));

                }else {
                    gameOver();

                }}

        });
                }


        private void updateQuestion(int num){
            question.setText(mQuestion.getQuestion(num));
            answer1.setText(mQuestion.getChoice1(num));
            answer2.setText(mQuestion.getChoice2(num));
            answer3.setText(mQuestion.getChoice3(num));
            answer4.setText(mQuestion.getChoice4(num));

            mAnswer = mQuestion.getCorrectAnswer(num);

        }

        private void gameOver(){
            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(Main2Activity.this);
            alertDialogBuilder
                    .setMessage("Game Over! Your Score is" + mScore + "points.")
                    .setCancelable(false)
                    .setPositiveButton("New Game",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int i) {
                                    startActivity(new Intent(getApplicationContext(), Main2Activity.class));
                                    finish();

                                }
                            })
                    .setNegativeButton ("Exit",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int i) {
                                    finish();

                }
            });
            AlertDialog alertDialog = alertDialogBuilder.create();
            alertDialog.show();

                    }}