Question

在[dateView.setText（tempDate）;]获取NullPointerException ...请提示？基本上我需要从日历中获取更改日期，然后使用这个新日期更新TextView。感谢。

CalendarView calendar;
String tempDate;
TextView dateView;

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

    dateView = (TextView)findViewById(R.id.TextDate);

    setContentView(R.layout.calendar);
    initializeCalendar();

}

public void initializeCalendar() {
    calendar = (CalendarView) findViewById(R.id.calendar);
    calendar.setShowWeekNumber(false);
    calendar.setFirstDayOfWeek(2);
    calendar.setSelectedWeekBackgroundColor(getResources().getColor(R.color.lightblue));
    calendar.setUnfocusedMonthDateColor(getResources().getColor(R.color.transparent));
    calendar.setWeekSeparatorLineColor(getResources().getColor(R.color.transparent));
    calendar.setSelectedDateVerticalBar(R.color.blue);
    calendar.setOnDateChangeListener(new OnDateChangeListener() {
        @Override
        public void onSelectedDayChange(CalendarView view, int year, int month, int day) {
            Toast.makeText(getApplicationContext(), day + "/" + month + "/" + year, Toast.LENGTH_LONG).show();
            tempDate = (day+"/"+month+"/"+year);
            dateView.setText(tempDate);
        }
    });
}

}

错误报告：

java.lang.NullPointerException
        at training.mark.trainingii.Calendar$1.onSelectedDayChange(Calendar.java:40)
        at android.widget.CalendarView$1.onChanged(CalendarView.java:1012)
        at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
        at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50)
        at android.widget.CalendarView$WeeksAdapter.setSelectedDay(CalendarView.java:1375)
        at android.widget.CalendarView$WeeksAdapter.onDateTapped(CalendarView.java:1460)
        at android.widget.CalendarView$WeeksAdapter.onTouch(CalendarView.java:1448)
        at android.view.View.dispatchTouchEvent(View.java:7708)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2329)
        at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1568)
        at android.app.Activity.dispatchTouchEvent(Activity.java:2458)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2277)
        at android.view.View.dispatchPointerEvent(View.java:7893)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3954)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3833)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3449)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3418)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3525)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3426)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3582)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3449)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3418)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3426)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
        at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5602)
        at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5582)
        at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5553)
        at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5682)
        at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:138)
        at android.os.Looper.loop(Looper.java:123)
        at android.app.ActivityThread.main(ActivityThread.java:5081)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
        at dalvik.system.NativeStart.main(Native

Answer 1

更改订单

setContentView(R.layout.calendar);
dateView = (TextView)findViewById(R.id.TextDate);

您应首先setContentView(R.layout.calendar);，然后初始化Views。

Android：方法中setText的java.lang.NullPointerException

1 个答案: