Question

我有一个活动（ChoozQr2），它在一个单独的类（ChoozQr2Adapter）中显示带有自定义适配器的列表视图。在那个自定义适配器中，我有2个时间戳和一些描述这两个时间选择器之间行为的代码。问题是：此行为仅适用于listview中的最后一项。我已阅读了几篇文章并尝试最近添加一个视图，但现在它在自定义适配器活动结束时在私有静态类ViewHolder上抛出了一个java.lang.Nullpointerexception（参见2）。

非常感谢您的帮助！

这是我的最后一段代码 1.使用listview调用适配器的活动代码：

public class ChoozQr2 extends Activity implements OnClickListener{
Button fini;    
ListView lv;
Context context;
ChoozQr2Adapter adapter;
ArrayList<String> resultArr;
TextView tvNomDuQr;
NumberPicker npNbJours,OccAlarme;
DatePicker dateFirstOcc;
TimePicker StartTime, StopTime;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.choozqr_step2);

    //declarations
    fini = (Button) findViewById(R.id.fini);

    lv = (ListView) findViewById(R.id.listView1);

    fini.setOnClickListener(this);

    //retrieve data from choozqr
    Bundle b = getIntent().getExtras(); 
    String[] sTemp = b.getStringArray("selectedItems");     
    resultArr = new ArrayList<String>(Arrays.asList(sTemp));

    //set up adapter
    adapter = new ChoozQr2Adapter(this, R.layout.choozqr_step2_textview, resultArr,new BtnClickListener() {
        @Override
        public void onBtnClick(int position) {
            resultArr.add(resultArr.get(position));
            lv.setAdapter(adapter);             
        }
    });

    lv.setAdapter(adapter);
    lv.setChoiceMode(ListView.CHOICE_MODE_SINGLE);  
}
(...)

自定义适配器代码：

public class ChoozQr2Adapter extends ArrayAdapter<String> { 
private final List<String> list;    
BtnClickListener mClickListener = null; 
TimePicker StartTime,StopTime;
DatePicker dateFirstOcc;
NumberPicker npNbJours, OccAlarme;
TextView tvNomDuQr;
Button Btn1,Btn2;
boolean OccAlarmeNotChanged = true;
ViewHolder holder;



public ChoozQr2Adapter(Context context, int resource, List<String> items,BtnClickListener listener) {
    super(context, resource, items);
    list = items;
    mClickListener = listener;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) { 
    View v = convertView;

    if (v == null) {
        LayoutInflater vi = LayoutInflater.from(getContext());
        v = vi.inflate(R.layout.choozqr_step2_textview, parent, false);

        ViewHolder holder = new ViewHolder();    

        holder.tvNomDuQr=(TextView)v.findViewById(R.id.NomQr);
        holder.npNbJours=(NumberPicker)v.findViewById(R.id.numberPickerOccurence);
        holder.OccAlarme=(NumberPicker)v.findViewById(R.id.OccAlarme);
        holder.dateFirstOcc=(DatePicker)v.findViewById(R.id.datePicker1erJour);
        holder.StartTime=(TimePicker)v.findViewById(R.id.timePickerHeureDebut);
        holder.StopTime=(TimePicker)v.findViewById(R.id.timePickerHeureFin);
        holder.Btn1=(Button)v.findViewById(R.id.Btn1);

        //Btn1      
        holder.Btn1.setTag(position);
        holder.Btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mClickListener != null)
                    mClickListener.onBtnClick((Integer) v.getTag());                
            }
        });


        //initialisations time&date picker
        Calendar now = Calendar.getInstance();
        now.add(Calendar.DAY_OF_MONTH, 1);
        holder.StartTime.setIs24HourView(true);
        holder.StopTime.setIs24HourView(true);  


        //When StartTime is changed and is equal to stopTime, put the StopTime one hour later
        holder.StartTime.setOnTimeChangedListener(new OnTimeChangedListener(){
            public void onTimeChanged(TimePicker v, int hourOfDay, int minute) {

                ViewHolder holder = (ViewHolder) v.getTag();                
                holder.StopTime.setCurrentHour(holder.StartTime.getCurrentHour()+1);
                holder.StopTime.setCurrentMinute(holder.StartTime.getCurrentMinute());
            }});

        holder.OccAlarme.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
            @Override
            public void onValueChange(NumberPicker arg0, int arg1, int arg2) {
                OccAlarmeNotChanged=false;
            }
        });

        //When StopTime changes...
        holder.StopTime.setOnTimeChangedListener(new OnTimeChangedListener(){
            public void onTimeChanged(TimePicker v, int hourOfDay, int minute) {

                ViewHolder holder = (ViewHolder) v.getTag();

                //...and is equal to startTime, put the StartTime one hour earlier
                if(holder.StartTime.getCurrentHour().equals(holder.StopTime.getCurrentHour())){
                    holder.StartTime.setCurrentHour(holder.StartTime.getCurrentHour()+1);
                }               

                //...and OccAlarme has not been set by user already
                if(OccAlarmeNotChanged){
                    //Then OccAlarme is updated to half time between start and end time
                    int i = (Math.abs((holder.StartTime.getCurrentHour() - holder.StopTime.getCurrentHour())))*30;
                    holder.OccAlarme.setValue(i);
                    holder.OccAlarme.setMaxValue(2*i);
                }
            }});            

        v.setTag(holder);  // set tag on view           

    } else { 
        holder = (ViewHolder) v.getTag();           
    }                       
    return v;
}    
private static class ViewHolder {
    private TextView tvNomDuQr;
    private NumberPicker npNbJours;
    private NumberPicker OccAlarme;     
    private TimePicker StartTime;
    private TimePicker StopTime;
    private DatePicker dateFirstOcc;
    private Button Btn1;
    //private Button Btn2;
}
}

这是logcat：

07-02 09:38:22.743: E/AndroidRuntime(20161): FATAL EXCEPTION: main
07-02 09:38:22.743: E/AndroidRuntime(20161): Process: fr.XXX.XXX, PID: 20161
07-02 09:38:22.743: E/AndroidRuntime(20161): java.lang.NullPointerException
07-02 09:38:22.743: E/AndroidRuntime(20161):    at fr.XXX.XXX.ChoozQr2Adapter$ViewHolder.access$12(ChoozQr2Adapter.java:193)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at fr.XXX.XXX.ChoozQr2Adapter$4.onTimeChanged(ChoozQr2Adapter.java:132)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.TimePicker.onTimeChanged(TimePicker.java:656)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.TimePicker.access$300(TimePicker.java:62)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.TimePicker$2.onValueChange(TimePicker.java:167)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.NumberPicker.notifyChange(NumberPicker.java:1835)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.NumberPicker.setValueInternal(NumberPicker.java:1621)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.NumberPicker.scrollBy(NumberPicker.java:1107)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.NumberPicker.onTouchEvent(NumberPicker.java:889)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.View.dispatchTouchEvent(View.java:7837)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2210)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.widget.NumberPicker.dispatchTouchEvent(NumberPicker.java:946)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2075)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1522)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.app.Activity.dispatchTouchEvent(Activity.java:2458)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2023)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.View.dispatchPointerEvent(View.java:8017)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3966)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3845)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3455)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3424)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3531)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3432)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3588)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3455)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3424)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3432)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5554)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5534)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5505)
07-02 09:38:22.743: E/AndroidRuntime(20161):    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5634)

Answer 1

问题是视图持有者，因为您多次使用相同的名称，因此只需通过以下代码更改您的适配器，

     public class ChoozQr2Adapter extends ArrayAdapter<String> 
     { 
         private final List<String> list;    
         BtnClickListener mClickListener = null; 
         boolean OccAlarmeNotChanged = true;


         public ChoozQr2Adapter(Context context, int resource, List<String> items,BtnClickListener listener) {
              super(context, resource, items);
              list = items;
              mClickListener = listener;
         }

         @Override
         public View getView(int position, View convertView, ViewGroup parent) { 

          ViewHolder holder = null;
          View v = convertView;

          if (v == null) {
                LayoutInflater vi = LayoutInflater.from(getContext());
               v = vi.inflate(R.layout.choozqr_step2_textview, parent, false);

               holder = new ViewHolder();    

               holder.tvNomDuQr=(TextView)v.findViewById(R.id.NomQr);
               holder.npNbJours=(NumberPicker)v.findViewById(R.id.numberPickerOccurence);
               holder.OccAlarme=(NumberPicker)v.findViewById(R.id.OccAlarme);
               holder.dateFirstOcc=(DatePicker)v.findViewById(R.id.datePicker1erJour);
               holder.StartTime=(TimePicker)v.findViewById(R.id.timePickerHeureDebut);
               holder.StopTime=(TimePicker)v.findViewById(R.id.timePickerHeureFin);
               holder.Btn1=(Button)v.findViewById(R.id.Btn1);               

             v.setTag(holder);  // set tag on view           

           } 
           else { 
             holder = (ViewHolder) v.getTag();           
           }      


    //Btn1      
    holder.Btn1.setTag(position);
    holder.Btn1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(mClickListener != null)
                mClickListener.onBtnClick((Integer) v.getTag());                
        }
    });


    //initialisations time&date picker
    Calendar now = Calendar.getInstance();
    now.add(Calendar.DAY_OF_MONTH, 1);
    holder.StartTime.setIs24HourView(true);
    holder.StopTime.setIs24HourView(true);  


    //When StartTime is changed and is equal to stopTime, put the StopTime one hour later
    holder.StartTime.setOnTimeChangedListener(new OnTimeChangedListener(){
        public void onTimeChanged(TimePicker v, int hourOfDay, int minute) {

            ViewHolder selectedHolder = (ViewHolder) v.getTag();                
            selectedHolder.StopTime.setCurrentHour(selectedHolder.StartTime.getCurrentHour()+1);
            selectedHolder.StopTime.setCurrentMinute(selectedHolder.StartTime.getCurrentMinute());
        }});

    holder.OccAlarme.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
        @Override
        public void onValueChange(NumberPicker arg0, int arg1, int arg2) {
            OccAlarmeNotChanged=false;
        }
    });

    //When StopTime changes...
    holder.StopTime.setOnTimeChangedListener(new OnTimeChangedListener(){
        public void onTimeChanged(TimePicker v, int hourOfDay, int minute) {

            ViewHolder selectedHolder = (ViewHolder) v.getTag();

            //...and is equal to startTime, put the StartTime one hour earlier
            if(selectedHolder.StartTime.getCurrentHour().equals(selectedHolder.StopTime.getCurrentHour())){
                selectedHolder.StartTime.setCurrentHour(selectedHolder.StartTime.getCurrentHour()+1);
            }               

            //...and OccAlarme has not been set by user already
            if(OccAlarmeNotChanged){
                //Then OccAlarme is updated to half time between start and end time
                int i = (Math.abs((selectedHolder.StartTime.getCurrentHour() - selectedHolder.StopTime.getCurrentHour())))*30;
                selectedHolder.OccAlarme.setValue(i);
                selectedHolder.OccAlarme.setMaxValue(2*i);
            }
        }});      

    return v;
 }    

    private static class ViewHolder
    {
        private TextView tvNomDuQr;
        private NumberPicker npNbJours;
        private NumberPicker OccAlarme;     
        private TimePicker StartTime;
        private TimePicker StopTime;
        private DatePicker dateFirstOcc;
        private Button Btn1;
        //private Button Btn2;
    }
}

Android自定义适配器：ViewHolder抛出java.lang.Nullpointerexception

1 个答案: