Force Close on Changing time: Time Picker (NPE)

问题:

When I click on the time picker for changing the time I get force close.

Can anybody tell me where is the problem in my code. Android. and this is my code......

timePickerDateTimePickerPopup = (TimePicker) layoutDateTimePickerPopup.findViewById(R.id.timePicker_datetimepicker);
            timePickerDateTimePickerPopup.setDescendantFocusability(TimePicker.FOCUS_BLOCK_DESCENDANTS);
            timePickerDateTimePickerPopup.setIs24HourView(true);
            timePickerDateTimePickerPopup.setCurrentHour(mCalendar.get(Calendar.HOUR_OF_DAY));
            timePickerDateTimePickerPopup.setCurrentMinute(mCalendar.get(Calendar.MINUTE));

            timePickerDateTimePickerPopup.setOnTimeChangedListener(this);

            dateTimePickerPopup.setTouchable(true);
            dateTimePickerPopup.setFocusable(true);
            dateTimePickerPopup.setOutsideTouchable(true);
            Drawable image_saved = context.getResources().getDrawable(R.drawable.dummy_bg);
            dateTimePickerPopup.setBackgroundDrawable(image_saved);

My Logcat shows a NullPointerException:

STACK_TRACE=java.lang.NullPointerException
at android.widget.TimePicker.updateInputState(TimePicker.java:553)
at android.widget.TimePicker.access$000(TimePicker.java:55)
at android.widget.TimePicker$2.onValueChange(TimePicker.java:149)
at android.widget.NumberPicker.notifyChange(NumberPicker.java:1777)
at android.widget.NumberPicker.changeCurrent(NumberPicker.java:1455)
at android.widget.NumberPicker.changeCurrentByOne(NumberPicker.java:1481)
at android.widget.NumberPicker.access$100(NumberPicker.java:70)
at android.widget.NumberPicker$2.onClick(NumberPicker.java:592)
at android.view.View.performClick(View.java:3519)
at android.view.View$PerformClick.run(View.java:14140)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
at dalvik.system.NativeStart.main(Native Method)

回答1:

This is a known native android bug. See bug #24387 in Android Bug Tracker.

回答2:

Changing the theme of my application to android:Theme.Black in my AndroidManifest.xml. solved the problem for me.

adding this style to styles.xml

The style of my fragment looks different but now it works.

Update: I have fixed this issue without changing the style, adding the property android:descendantFocusability="blocksDescendants" to my TimePicker

<TimePicker
    android:id="@+id/toTimePicker"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:descendantFocusability="blocksDescendants" />

回答3:

As said, it seems to be a known bug. A possible work-around can be iterating through children until you find EditText and set it "focusable" property to false.

Recursively,

// level is just a counter for reading better Logs
private void hideFocusable(ViewGroup vg, int level)
{
    for(int i=0; i < vg.getChildCount(); i++) 
    {
        try
        {
               ViewGroup vt = (ViewGroup) vg.getChildAt(i);
               Log.i("NODE",level+") "+ vg.getChildAt(i).getClass().getName()); 

               hideFocusable(vt, level+1);

        }catch (ClassCastException e) {
                View vf = (View) vg.getChildAt(i);

                Log.i("LEAF",level+") "+ vf.getClass().getName());

                // here you can pick EditText and setFocusable to false 
                if(vf.getClass().equals(EditText.class))
                   vf.setFocusable(false);

        }

    }
}