Next Button does not work

Android Programming (3rd Edition) 2. Android and Model-View-Controller
1

My next button does nothing. My code is below: I looked back to the earlier parts of the chapter in case I forgot to type something. However, I cannot find what I missed.

package com.bignerdranch.android.geoquiz;

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

public class QuizActivity extends AppCompatActivity {

    private Button mTrueButton;
    private Button mFalseButton;
    private Button mNextButton;
    private TextView mQuestionTextView;

    private Question[] mQuestionBank = new Question[] {
            new Question(R.string.question_australia, true),
            new Question(R.string.question_oceans, true),
            new Question(R.string.question_mideast, false),
            new Question(R.string.question_africa, false),
            new Question(R.string.question_americas, true),
            new Question(R.string.question_asia, true)
    };

    private int mCurrentIndex = 0;


    public QuizActivity() {
    }

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

        mQuestionTextView = (TextView) findViewById(R.id.question_text_view);

        mTrueButton = (Button) findViewById(R.id.true_button);
        mTrueButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                checkAnswer(true);
            }
        });
        mFalseButton = (Button) findViewById(R.id.false_button);
        mFalseButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                checkAnswer(false);
            }
        });

        mNextButton = (Button) findViewById(R.id.next_button);
        mNextButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
            }
        });

        updateQuestion();
    }

    private void updateQuestion() {
        int question = mQuestionBank[mCurrentIndex].getTextResId();

        mQuestionTextView.setText(question);
    }

    private void checkAnswer(boolean userPressedTrue) {
        boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();

        int messageResId = 0;

        if (userPressedTrue == answerIsTrue) {
            messageResId = R.string.correct_toast;
        } else {
            messageResId = R.string.incorrect_toast;
        }

        Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show();
    }
}
2

you put your updateQuestion on wrong place in next button listioner.

3

I have noted 2 errors in your code.

  1. You are not updating the question text view when you click the next button i.e., you must call the
    updateQuestion() method in the onClick() method of the next button i.e.,

             mNextButton = (Button) findViewById(R.id.next_button);
         mNextButton.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
             mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
             updateQuestion(); //YOU ARE MISSING THIS METHOD CALL
         }
     });

That method call is important because every time when the next button is clicked the question text view has to be updated with the next question right, and that update cannot be done without calling the updateQuestion() method.

  1. In the updateQuestion() method why are you calling getTextResId() method in the first line???

    I tried to use that method but Android Studio failed to even recognize the method!!!

    In my code I call the getQuestion() method which I declared in the TrueFalse.java class and it works!!

int question = mQuestionBank[mCurrentIndex].getQuestion();

You can do the same stuff with your code and I hope that it will work.

In any case please let me know :slight_smile:

4

I got it working, thanks.