Question

我有＆lt;＆gt;和＆lt;＆gt;我的测验应用程序中的按钮，但如果用户是第一个问题，因为没有先前的问题，应该有toast，其中“这是第一个问题”，并且与＆lt;＆gt;按钮相同。

这是我的按钮代码（不正确）：

 mNextButton = (Button)findViewById(R.id.next_button);

    mNextButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
                mCurreentIndex=0;
                if (mCurreentIndex>mQuestionBank.length){
                    Toast.makeText(QuizActivity.this,R.string.last_question,Toast.LENGTH_LONG).show();
                }
            updateQuestion();
        }
    });

    mPreviousButton = (Button)findViewById(R.id.previous_button);

    mPreviousButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mCurreentIndex--;
            if (mCurreentIndex<mQuestionBank.length){
                Toast.makeText(QuizActivity.this, R.string.first_question,Toast.LENGTH_LONG).show();
            }

            updateQuestion();
        }
    });

Answer 1

//上一个按钮条件;

   mCurreentIndex--; 
if (mCurreentIndex<mQuestionBank.length && mCurreentIndex>=0){
                Toast.makeText(QuizActivity.this, R.string.first_question,Toast.LENGTH_LONG).show();
            }
else {
  Toast.makeText(QuizActivity.this, "This is first question",Toast.LENGTH_LONG).show();
mCurreentIndex++; 
}

//下一个按钮条件;

 mCurreentIndex++;
                if (mCurreentIndex<mQuestionBank.length){
                    Toast.makeText(QuizActivity.this,R.string.last_question,Toast.LENGTH_LONG).show();
                }

else {
  Toast.makeText(QuizActivity.this, "This is last Question",Toast.LENGTH_LONG).show();
mCurreentIndex--;
}

Answer 2

mNextButton = (Button)findViewById(R.id.next_button);

 mNextButton.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
             //mCurreentIndex=0;// not valid
             if (mCurreentIndex>=mQuestionBank.length){
                 Toast.makeText(QuizActivity.this,getString(R.string.last_question),Toast.LENGTH_LONG).show();
                return;
             }
        mCurreentIndex++;
         updateQuestion();
     }
 });

 mPreviousButton = (Button)findViewById(R.id.previous_button);

 mPreviousButton.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {

         if (mCurreentIndex<=0){
             Toast.makeText(QuizActivity.this, getString(R.string.first_question),Toast.LENGTH_LONG).show();
            return;
         }
        mCurreentIndex--;
         updateQuestion();
     }
 });

Answer 3

试试这个

mPreviousButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mCurreentIndex<=0){
                Toast.makeText(QuizActivity.this, R.string.first_question,Toast.LENGTH_LONG).show();
            }else{
                mCurreentIndex--;
                updateQuestion();
            }
        }
    });



 mNextButton.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
         if (mCurreentIndex>=mQuestionBank.length){

             Toast.makeText(QuizActivity.this,getString(R.string.last_question),Toast.LENGTH_LONG).show();

         }else{
             mCurreentIndex++;
             updateQuestion();
        }

 }

}）;

Answer 4

您刚刚显示toast消息，但下一个语句也会在显示toast后执行。对于您的解决方案，您需要使用“返回”或 if..else 阻止。

     mNextButton = (Button)findViewById(R.id.next_button);

        mNextButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    mCurreentIndex=0;
                    if (mCurreentIndex>mQuestionBank.length){
                        Toast.makeText(QuizActivity.this,R.string.last_question,Toast.LENGTH_LONG).show();
                        return;
                    }
                updateQuestion();
            }
        });

        mPreviousButton = (Button)findViewById(R.id.previous_button);

        mPreviousButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mCurreentIndex--;
                if (mCurreentIndex<mQuestionBank.length){
                    Toast.makeText(QuizActivity.this, R.string.first_question,Toast.LENGTH_LONG).show();
                    return;
                }

                updateQuestion();
            }
        });

Answer 5

公共类QuizActivity扩展了AppCompatActivity {

private static final String TAG = "QuizActivity";
private static final String KEY_INDEX = "index";

private Button mTrueButton;
private Button mFalseButton;
private Button mNextButton;
private Button mPreviousButton;
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 mCurreentIndex = 0;

private boolean[] QuestionsAnswered = new boolean[mQuestionBank.length];

@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.d(TAG,"onCreate(Bundle) called");
    setContentView(R.layout.activity_quiz);

    if (savedInstanceState != null) {
     mCurreentIndex =savedInstanceState.getInt(KEY_INDEX, 0);
     QuestionsAnswered = savedInstanceState.getBooleanArray(KEY_INDEX);
    }

    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) {
            mCurreentIndex = (mCurreentIndex+mQuestionBank.length +1) % mQuestionBank.length;
            updateQuestion();
        }
    });

    mPreviousButton = (Button)findViewById(R.id.previous_button);

    mPreviousButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mCurreentIndex= (mCurreentIndex+ mQuestionBank.length - 1) % mQuestionBank.length;
            updateQuestion();
        }
    });

updateQuestion（）; }

@Override
protected void onStart() {
    super.onStart();
    Log.d(TAG, "onStart() called");
}

@Override
protected void onResume() {
    super.onResume();
    Log.d(TAG, "onResume() called");
}

@Override
protected void onPause() {
    super.onPause();
    Log.d(TAG, "onPause() called");
}

@Override
protected void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putInt(KEY_INDEX,mCurreentIndex);
    savedInstanceState.putBooleanArray(KEY_INDEX,QuestionsAnswered);
}

@Override
protected void onStop() {
    super.onStop();
    Log.d(TAG, "onStop() called");
}

@Override
protected void onDestroy() {
    super.onDestroy();
    Log.d(TAG, "onDestroy() called");
}

private void updateQuestion(){
    int question = mQuestionBank[mCurreentIndex].getTextResId();
    mQuestionTextView.setText(question);
    mTrueButton.setEnabled(!QuestionsAnswered[mCurreentIndex]);
    mFalseButton.setEnabled(!QuestionsAnswered[mCurreentIndex]);
}

private void checkAnswer(boolean userPressedTrue) {
    boolean answerIsTrue = mQuestionBank[mCurreentIndex].isAnswerTrue();
    int messageResId = 0;

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

    } else {
        messageResId = R.string.incorrect_toast;
    }
    Toast.makeText(this, messageResId, Toast.LENGTH_LONG).show();
    QuestionsAnswered[mCurreentIndex] = true;
    mTrueButton.setEnabled(false);
    mFalseButton.setEnabled(false);

}

}

上一个按钮和下一个按钮

5 个答案: