Как создать кнопку «Назад» в приложении для викторины

Question

, поэтому я хочу создать кнопку «Назад» в приложении для викторины. Все вопросы взяты из базы данных SQ. Я хочу, чтобы кнопка переходила к предыдущему вопросу, не испортив счетчик. Любая идея, как я это сделаю ??? :-) Спасибо, что посмотрели. Мой код

import java.util.List; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.KeyEvent; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.RadioButton; 
import android.widget.TextView; 

import com.tmm.android.chuck.quiz.GamePlay; 
import com.tmm.android.chuck.quiz.Question; 
import com.tmm.android.chuck.util.Utility; 

/** 
* @author Derek McAuley 
* 
*/ 
public class QuestionActivity extends Activity implements OnClickListener{ 

    private Question currentQ; 
    private GamePlay currentGame; 



    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.question); 
     /** 
     * Configure current game and get question 
     */ 
     currentGame = ((ChuckApplication)getApplication()).getCurrentGame(); 
     currentQ = currentGame.getNextQuestion(); 



     Button nextBtn = (Button) findViewById(R.id.nextBtn); 
     nextBtn.setOnClickListener(this); 

     /** 
     * Update the question and answer options.. 
     */ 
     setQuestions(); 

    } 


    /** 
    * Method to set the text for the question and answers from the current games 
    * current question 
    */ 
    private void setQuestions() { 
     //set the question text from current question 
     String question = Utility.capitalise(currentQ.getQuestion()); 
     TextView qText = (TextView) findViewById(R.id.question); 
     qText.setText(question); 

     //set the available options 
     List<String> answers = currentQ.getQuestionOptions(); 
     TextView option1 = (TextView) findViewById(R.id.answer1); 
     option1.setText(Utility.capitalise(answers.get(0))); 

     TextView option2 = (TextView) findViewById(R.id.answer2); 
     option2.setText(Utility.capitalise(answers.get(1))); 

     TextView option3 = (TextView) findViewById(R.id.answer3); 
     option3.setText(Utility.capitalise(answers.get(2))); 

     TextView option4 = (TextView) findViewById(R.id.answer4); 
     option4.setText(Utility.capitalise(answers.get(3))); 


     // below is the question counter which displays the current question number is the left corner. 
     // it also displays the number of questions in the test. 
     int total =currentGame.getNumRounds(); 
     int to = currentGame.getRound(); 
     TextView questionNum = (TextView) findViewById(R.id.textView1); 
     questionNum.setText("Question " + to +"/" + total); 
    } 


    @Override 
    public void onClick(View arg0) { 
     //Log.d("Questions", "Moving to next question"); 

     /** 
     * validate a checkbox has been selected 
     */ 
     if (!checkAnswer()) return; 


     /** 
     * check if end of game 
     */ 
     if (currentGame.isGameOver()){ 
      //Log.d("Questions", "End of game! lets add up the scores.."); 
      //Log.d("Questions", "Questions Correct: " + currentGame.getRight()); 
      //Log.d("Questions", "Questions Wrong: " + currentGame.getWrong()); 
      Intent i = new Intent(this, EndgameActivity.class); 
      startActivity(i); 
      finish(); 
     } 
     else{ 
      Intent i = new Intent(this, QuestionActivity.class); 
      startActivity(i); 
      finish(); 
     } 
    } 


    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) 
    { 
     switch (keyCode) 
     { 
     case KeyEvent.KEYCODE_BACK : 
      return true; 
     } 

     return super.onKeyDown(keyCode, event); 
    } 


    /** 
    * Check if a checkbox has been selected, and if it 
    * has then check if its correct and update gamescore 
    */ 
    private boolean checkAnswer() { 
     String answer = getSelectedAnswer(); 
     if (answer==null){ 
      //Log.d("Questions", "No Checkbox selection made - returning"); 
      return false; 
     } 
     else { 
      //Log.d("Questions", "Valid Checkbox selection made - check if correct"); 
      if (currentQ.getAnswer().equalsIgnoreCase(answer)) 
      { 
       //Log.d("Questions", "Correct Answer!"); 
       currentGame.incrementRightAnswers(); 
      } 
      else{ 
       //Log.d("Questions", "Incorrect Answer!"); 
       currentGame.incrementWrongAnswers(); 


      } 
      return true; 
     } 
    } 


    /** 
    * 
    */ 
    private String getSelectedAnswer() { 
     RadioButton c1 = (RadioButton)findViewById(R.id.answer1); 
     RadioButton c2 = (RadioButton)findViewById(R.id.answer2); 
     RadioButton c3 = (RadioButton)findViewById(R.id.answer3); 
     RadioButton c4 = (RadioButton)findViewById(R.id.answer4); 
     if (c1.isChecked()) 
     { 
      return c1.getText().toString(); 
     } 
     if (c2.isChecked()) 
     { 
      return c2.getText().toString(); 
     } 
     if (c3.isChecked()) 
     { 
      return c3.getText().toString(); 
     } 
     if (c4.isChecked()) 
     { 
      return c4.getText().toString(); 
     } 

     return null; 
    } 

} 

Answer 1

Вы должны быть в состоянии сделать это, перекрывая onBackPressed() http://developer.android.com/reference/android/app/Activity.html#onBackPressed%28%29 - это означает, что вы можете удалить переопределение метода OnKeyDown

Например:

@Override 
onBackPressed() { 
    if (currentGame.hasPreviousQuestion()) { 
     currentGame.loadPreviousQuestion(); 
     setQuestions(); 
    } else { 
     // pass call back to super class to be handled 
     super.onBackPressed(); 
    } 
}