安卓自定义适配器: ViewHolder抛出一个java.lang.Nullpointerexception
安卓自定义适配器: ViewHolder抛出一个java.lang.Nullpointerexception
提问于 2016-07-01 21:55:30
我有一个活动(ChoozQr2)，它在单独的类(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，我有两个时间选择器和一些代码来描述这两个时间选择器之间的行为。问题是:这种行为只适用于列表视图中的最后一项。我读过几篇文章，并试图在最近添加一个viewholder，但现在它在自定义适配器活动结束时在私有静态类java.lang.Nullpointerexception上抛出一个ViewHolder (参见2)。
你的帮助真的很感激！
下面是我最后的代码1。带有调用适配器的listview的活动的代码：
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： 公共类ChoozQr2Adapter扩展了ArrayAdapter {私有最终列表列表；BtnClickListener mClickListener = null；TimePicker StartTime，StopTime；DatePicker dateFirstOcc；NumberPicker npNbJours，OccAlarme；TextView tvNomDuQr；Button Btn1，Btn2；boolean = true；Btn2；public OccAlarmeNotChanged (上下文、int资源、列表项、侦听器){超级(上下文、资源、项)；list = items；=侦听器；}@覆盖公共视图(int位置，View，父){ View v=；如果(v holder.npNbJours=(NumberPicker)v.findViewById(R.id.numberPickerOccurence)；null) { LayoutInflater vi = LayoutInflater.from(getContext())；v= vi.inflate(R.layout.choozqr_step2_textview，父级，false)；ViewHolder holder = new ViewHolder()；LayoutInflater 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 1 Holder.btn1.setTag(位置)；Btn1.setOnClickListener(新的View.OnClickListener() { @Override (View v) ){ if(mClickListener != null) mClickListener.onBtnClick((Integer) v.getTag()；} })；//初始化时间和日期选择器日历现在= Calendar.getInstance()；now.add(Calendar.DAY_OF_MONTH，1)；holder.StartTime.setIs24HourView(真)；holder.StopTime.setIs24HourView(真)；//当StartTime被更改并等于stopTime时，在1小时后将StopTime (新的OnTimeChangedListener())(新的OnTimeChangedListener()){ public holder.StartTime.setOnTimeChangedListener(TimePicker v，int hourOfDay，int分钟){ ViewHolder holder = (ViewHolder) v.getTag()；( holder.StopTime.setCurrentHour(holder.StartTime.getCurrentHour()+1)；holder.StopTime.setCurrentMinute(holder.StartTime.getCurrentMinute())；})；holder.OccAlarme.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {@重写公共无效onValueChange(NumberPicker arg0，int arg1，int arg2) { OccAlarmeNotChanged=false；)；//当StopTime发生变化时.Holder.StopTime.setOnTimeChangedListener(新OnTimeChangedListener(){ public void onTimeChanged(TimePicker v，int hourOfDay，int分钟)){ ViewHolder holder = (ViewHolder) v.getTag()；//.等于if(holder.StartTime.getCurrentHour().equals(holder.StopTime.getCurrentHour())){ holder.StartTime.setCurrentHour(holder.StartTime.getCurrentHour()+1)；的startTime，提前1小时放置StartTime}//.并且OccAlarme尚未由用户设置，如果(OccAlarmeNotChanged){//那么OccAlarme在开始和结束时间int =(Math.abs(holder.StartTime.getCurrentHour(holder.StartTime.getCurrentHour()-holder.StopTime.getCurrentHour()*30之间被更新为半时间)；holder.OccAlarme.setValue(i)；holder.OccAlarme.setMaxValue(2*i)；}；v.setTag( holder )；// set标签on view }{holder= (ViewHolder) v.getTag()；}返回v；}私有静态类ViewHolder { TextView tvNomDuQr；private NumberPicker npNbJours；private NumberPicker OccAlarme；private TimePicker StartTime；private TimePicker StopTime；private DatePicker dateFirstOcc；private Button Btn1；//private Button Btn2；}}
这就是逻辑猫：
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)回答 1
Stack Overflow用户
发布于 2016-07-02 09:24:33
问题是，由于您多次使用相同的名称，所以只需通过下面的代码更改适配器，
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;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/38154341
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