如何清除所有無線電組和setTextColor到Java中的一個單選按鈕？

Question

我已經動態地創建了2個單選按鈕組。每個單選按鈕代表一個問題的答案。我setOnCheckedChangeListener查看哪些漫遊者是正確的。所以，當我按下一個按鈕時，我想擁有所有電臺組clearCheck()以及正確答案setTextColor(Color.GREEN)。有了這段代碼，當我使用radioGroup[i].clearCheck();時，出現此錯誤：Attempt to invoke virtual method 'java.lang.Object android.widget.RadioButton.getTag()' on a null object reference。我怎樣才能解決這個問題？我怎樣才能設置文本顏色綠色，只有正確的答案？這裏是我的代碼：

 radioGroup[i].setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() { 

      @Override 
      public void onCheckedChanged(RadioGroup group, int checkedId) { 
       RadioButton checkedRadioButton = (RadioButton)group.findViewById(checkedId); 
       int CorrectAnswer = Integer.parseInt(checkedRadioButton.getTag().toString()); 
       switch (checkedId) { 
        case 0: 
         if (CorrectAnswer == 1) { 
          Toast.makeText(getApplicationContext(), "You clicked the correct answer ", Toast.LENGTH_SHORT).show(); 
          score++; 
         } else { 
          Toast.makeText(getApplicationContext(), "You clicked the incorrect answer ", Toast.LENGTH_SHORT).show(); 
         } 
         break; 
        case 1: 
         if (CorrectAnswer == 1) { 
          Toast.makeText(getApplicationContext(), "You clicked the correct answer ", Toast.LENGTH_SHORT).show(); 
          score++; 
         } else { 
          Toast.makeText(getApplicationContext(), "You clicked the incorrect answer ", Toast.LENGTH_SHORT).show(); 
         } 
         break; 
       } 
      } 
     }); 

     resetButton.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       for (int i = 0; i < radioGroup.length; i++) { 
        radioGroup[i].clearCheck(); // doesn't work 
        for (int j = 0; j < answer.length; j++) { 
         radioGroup[i].getChildAt(j).setBackgroundColor(Color.WHITE); 
         ((RadioButton) radioGroup[i].getChildAt(j)).setTextColor(Color.GREEN); 
        } 
       } 
      } 
     }); 

謝謝！

Answer 1

大概onCheckedChanged方法正在調用時clearCheck方法被調用以便補充null檢查在onCheckedChanged呼籲setTag方法toString()方法之前：

@Override 
    public void onCheckedChanged(RadioGroup group, int checkedId) { 
     RadioButton checkedRadioButton = (RadioButton)group.findViewById(checkedId); 
     if(checkedRadioButton!=null) 
     if(checkedRadioButton.getTag() !=null){ 
     int CorrectAnswer = Integer.parseInt(
         checkedRadioButton.getTag().toString()); 
      ....your code here 

     } 
    }