title: Double AddView on adapter
body: <p>I have made linear layout and add view on it, however, the view appear twice, I dont know why it happen.Can anyone fix it??
  I have problem about the adapter and I look few time and I find no strange here. But I delete the statement of addView it will not appear any View I have added before. </p>
  
  <pre><code>public View getView(int position, View convertView, ViewGroup parent) {
      // TODO Auto-generated method stub
      if(convertView == null)
      {
          LayoutInflater inflater = LayoutInflater.from(parent.getContext());
      //  inflater.inflate(R.layout. parent,false);
          convertView = inflater.inflate(R.layout.exerciseui_item,parent,false);
  
      }
      Exercise question = exercises.get(position);
      TextView question_view = (TextView) convertView.findViewById(R.id.exercise_question);
      String question_test = question.getOrder() + " " + question.getText()  ;
      question_view.setText(question_test);
      int answer_num = question.getAnswer().size();
  
      LinearLayout linear = (LinearLayout) convertView.findViewById(R.id.exercise_answer);
          ExerciseAnswer answer = question.getAnswer().get(0);
          int answer_order = answer.getOrder();
          String answer_text = answer.getText();
          String answer_final = answer_order + " " + answer_text;
          TextView answer_view = new TextView(linear.getContext());
          answer_view.setPadding(20, 5, 5, 5);
          answer_view.setTextSize(30);
          answer_view.setText(answer_final);
          linear.addView(answer_view);
  
  
      return convertView;
  }
  </code></pre>
  
  <p>The following is the xml of the exerciseui_item</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  android:id="@+id/exercise_answer" &gt;
  
  &lt;TextView
      android:id="@+id/exercise_question"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
  
      android:textSize="13dp"
      &gt;&lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  </code></pre>