如何文本顏色設置爲從所有無線電組中的所有單選按鈕在Java中

Question

我試圖設置文本顏色爲紅色，以所有單選按鈕，但是從我有所有的無線電組。什麼時候使用answer[i].setTextColor(Color.RED);這隻適用於最後一個無線電組。

如果嘗試將背景顏色更改爲與radioGroup[i].getChildAt(j).setBackgroundColor(Color.GREEN);的所有單選按鈕，則會出現以下錯誤：Attempt to invoke virtual method 'android.view.View android.widget.RadioGroup.getChildAt(int)' on a null object reference。

我該如何解決這個問題？有沒有其他方法可以做到這一點？
這裏是我的代碼：

radioGroup = new RadioGroup[4]; 
    answer = new RadioButton[4]; 
    for (Question qn : questions) { 
     int i = 0; 
     radioGroup[i] = new RadioGroup(this); 
     radioGroup[i].setOrientation(RadioGroup.VERTICAL); 
     int j = 0; 
     for (Answer an : answers) { 
      if (qn.getID() == an.getQuestion_id_answer()) { 
       String answers_log = " " + an.getAnswer(); 
       answer[j] = new RadioButton(this); 
       answer[j].setText(answers_log); 
       radioGroup[i].addView(answer[j]); 
       j++; 
      } 
     } 
     linearLayout.addView(radioGroup[i]); 
     i++; 
    } 

    finishButton = new Button(this); 
    linearLayout.addView(finishButton); 

    finishButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      for (int i = 0; i < radioGroup.length; i++) { 
       for (int j = 0; j < answer.length; j++) { 
        answer[i].setTextColor(Color.RED); 
       } 
      } 
     } 
    }); 

謝謝！

Answer 1

UPDATE

試試這個代碼：

radioGroup = new RadioGroup[4]; 
    answer = new RadioButton[4]; 
    int i = 0; 
    for (Question qn : questions) { 
     radioGroup[i] = new RadioGroup(this); 
     radioGroup[i].setOrientation(RadioGroup.VERTICAL); 
     int j = 0; 
     for (Answer an : answers) { 
      if (qn.getID() == an.getQuestion_id_answer()) { 
       String answers_log = " " + an.getAnswer(); 
       answer[j] = new RadioButton(this); 
       answer[j].setText(answers_log); 
       radioGroup[i].addView(answer[j]); 
       j++; 
      } 
     } 
     linearLayout.addView(radioGroup[i]); 
     i++; 
    } 

    finishButton = new Button(this); 
    linearLayout.addView(finishButton); 

    finishButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      for (int i = 0; i < radioGroup.length; i++) { 
       for (int j = 0; j < radioGroup[i].getChildCount(); j++) { 
        radioGroup[i].getChildAt(j).setBackgroundColor(Color.GREEN); 
       } 
      } 
     } 
    }); 

Answer 2

試試這個：

finishButton.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View v) { 
     for (int i = 0; i < 4; i++) { 
      radioGroup[i].clearCheck(); 
      for (int j = 0; j < 4; j++) { 
       radioGroup[i].getChildAt(j).setEnabled(true); 
       ((RadioButton)radioGroup[i].getChildAt(j)).setTextColor(Color.RED); 
       ((RadioButton)radioGroup[i].getChildAt(j)).setChecked(false); 
      } 
     } 
    } 
}); 

Answer 3

我很神奇！

ü只想得到4 RadioGroup和4 RadioButton？

變化for(b: bs)到for(int i = 0;i<bs.size();i++)

finishButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
     try{ 
      for (int i = 0; i < radioGroup.length; i++) { 
       int len = radioGroup[i].getChildCount(); 
       for (int j = 0; j < len; j++) { 
        radioGroup[i].getChildAt(j).setBackgroundColor(
          Color.GREEN); 
       } 
      } 
     }catch(Throwable e){ 
      } 

     } 
    });