的ListView setOnItemClicklistener NullPointerException異常

Question

public class CustomAdapter extends ArrayAdapter<Plan> implements View.OnClickListener { 

    private ArrayList<Plan> planArrayList; 
    int position; 
    Context context; 
    private static class ViewHolder{ 
     TextView workType; 
     TextView zone; 
     TextView division; 
     TextView station; 
     TextView Msg; 
    } 
    public CustomAdapter(ArrayList<Plan> plan,Context context){ 
     super(context,R.layout.plan_list,plan); 
     this.planArrayList=plan; 
     this.context=context; 

    } 
    @Override 
    public void onClick(View v) { 

    } 
    private int lastPosition = -1; 
    @NonNull 
    @Override 
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) { 
     Plan plans = getItem(position); 
     ViewHolder viewHolder; 
     final View result; 
     LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); 
     if (convertView == null){ 
      viewHolder = new ViewHolder(); 
      //LayoutInflater inflater = LayoutInflater.from(getContext()); 
      convertView = inflater.inflate(R.layout.plan_list,parent,false); 
      viewHolder.workType = (TextView) convertView.findViewById(R.id.plan_worktype); 
      viewHolder.zone = (TextView) convertView.findViewById(R.id.plan_zone); 
      viewHolder.division = (TextView) convertView.findViewById(R.id.plan_division); 
      viewHolder.station = (TextView) convertView.findViewById(R.id.plan_station); 
      viewHolder.Msg = (TextView) convertView.findViewById(R.id.) 
      result=convertView; 
      convertView.setTag(viewHolder); 
     }else { 
      viewHolder = (ViewHolder) convertView.getTag(); 
      result = convertView; 
     } 
     Animation animation = AnimationUtils.loadAnimation(context, (position > lastPosition) ? R.anim.up_from_bottom : R.anim.down_from_top); 
     result.startAnimation(animation); 
     Plan plan = planArrayList.get(position); 
     lastPosition = position; 
     viewHolder.workType.setText(plans.getWorkType()); 
     viewHolder.zone.setText(plans.getZone()); 
     viewHolder.division.setText(plans.getDiv()); 
     viewHolder.station.setText(plans.getSTA()); 
     viewHolder.workType.setText(plan.getWorkType()); 
     viewHolder.zone.setText(plan.getZone()); 
     viewHolder.division.setText(plan.getDiv()); 
     viewHolder.station.setText(plan.getSTA()); 

     if (this.position == position){ 
      View view2 = inflater.inflate(R.layout.list_dialog,null); 
      TextView worktype= (TextView) view2.findViewById(R.id.dlg_worktype); 
      TextView zone = (TextView) view2.findViewById(R.id.dlg_zone); 
      TextView div = (TextView) view2.findViewById(R.id.dlg_division); 
      TextView sta = (TextView) view2.findViewById(R.id.dlg_station); 
      TextView msg = (TextView) view2.findViewById(R.id.dlg_msg); 
      worktype.setText(plan.getWorkType()); 
      zone.setText(plan.getZone()); 
      div.setText(plan.getDiv()); 
      sta.setText(plan.getSTA()); 
      msg.setText(plan.getMsg()); 
      return view2; 
     } 
     return convertView; 
    } 
    public void selectedItem(int position){ 
     this.position=position; 
    } 
} 

當我listView項目這些項目的值需要在對話框中顯示名爲setOnItemClickListener。

通過上面的代碼我得到顯示java.lang.NullPointerException：嘗試從外地「android.widget.TextView com.example.nsurekha.entry_ex.CustomAdapter $ ViewHolder.workType」上的空對象引用閱讀

Answer 1

如果你想使用的onClick上的ListView

list.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 

      public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { 
       // TODO Auto-generated method stub 
       String title=adapter.getItem(arg2).getTitle(); 
       String description=adapter.getItem(arg2).getDescription(); 
       String addedby=adapter.getItem(arg2).getAddedby(); 

      } 
     }); 

現在你可以很容易地顯示出與期望的數據對話框。希望對你有效。