java - ArrayList 给出空指针异常

Question

我正在解析 XML 文件并将 XML 值分配给类变量。这也是主要的 Activity 和变量类:

package com.example.questions;

public class Test extends Activity 
{
  private TextView question;
  private RadioButton rdooption1;
  private RadioButton rdooption2;
  private RadioButton rdooption3;
  private RadioButton rdooption4;
  private static final String FILENAME = "xmlFileName.xml";
  private FileInputStream fin;


  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.question_layout);   
  }

  @SuppressWarnings("null")
  private void parseXML(XmlPullParser xpp) throws XmlPullParserException, IOException 
  {
    List<QuestionArrayList> questions = null;
    QuestionArrayList currentquestion = null;

    while(xpp.next()!=XmlPullParser.END_DOCUMENT )
    {

      questions= new ArrayList<QuestionArrayList>();

      if (xpp.getEventType() != XmlPullParser.START_TAG) 
      {
        continue;
      }

      String name = xpp.getName();

      if(name.equals("Question"))
      {
        //String questionmy = xpp.nextText();

        //here error is giving                                      
        currentquestion.question_name=xpp.nextText();
      }


      questions.add(currentquestion);
      System.out.println("Size of al after additions: " + questions.size());

      System.out.println("Contents of al: " + questions);

    }
  }      
}

这是变量类:

public class QuestionArrayList 
{
    public int question_set_id;
    public int question_id;
    public String question_type;
    public String question_name;
    public String option_one;
    public String option_two;
    public String option_three;
    public String option_four;
}

Answer 1

初始化您的QuestionArrayList类。您刚刚为其声明了变量。

currentquestion = new QuestionArrayList():