Question

因此，我是一个开始者，尝试从片段中打开按钮时无法打开时间选择器对话框时遇到麻烦。片段Work具有按钮（timeButton），当我按下它时，应用程序崩溃。我将提供错误消息和片段。

这是Work片段：

public class Work extends Fragment implements TimePickerDialog.OnTimeSetListener {

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.frag_work, container, false);
        getActivity().setTitle("Work");


        Button timeButton = (Button) view.findViewById(R.id.timeButton);
        timeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DialogFragment timePicker = new TimePicker_Fragment();
                timePicker.show(getFragmentManager(), "Time Picker");
            }
        });

        return view;
    }

    @Override
    public void onTimeSet(TimePicker timePicker, int i, int i1) {

    }
}

这是我的time dialog片段：

public class TimePicker_Fragment extends DialogFragment {
    @NonNull
    @Override
    public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {

        Calendar c = Calendar.getInstance();
        int hour = c.get(Calendar.HOUR_OF_DAY);
        int minute = c.get(Calendar.MINUTE);

        return new TimePickerDialog(getActivity(), (TimePickerDialog.OnTimeSetListener) getActivity(), hour, minute, DateFormat.is24HourFormat(getActivity()));
    }
}

这些是我收到的errors：

2019-07-02 17:29:15.419 30283-30283/com.example.worktime E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.worktime, PID: 30283
    java.lang.ClassCastException: com.example.worktime.MainActivity cannot be cast to android.app.TimePickerDialog$OnTimeSetListener
        at com.example.worktime.TimePicker_Fragment.onCreateDialog(TimePicker_Fragment.java:21)
        at androidx.fragment.app.DialogFragment.onGetLayoutInflater(DialogFragment.java:330)
        at androidx.fragment.app.Fragment.performGetLayoutInflater(Fragment.java:1308)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1460)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:802)
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
        at androidx.fragment.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7319)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:934)
2019-07-02 17:29:15.541 30283-30283/com.example.worktime I/Process: Sending signal. PID: 30283 SIG: 9

我该如何解决此问题？

Answer 1

实现 TimePickerDialog.OnTimeSetListener在您的 TimePicker_Fragment 类中。

您可以通过此链接Loading timePickerDialog from a fragment

了解更多有关自定义 TimePicker 的信息。

Answer 2

在例外情况下阅读此行。

java.lang.ClassCastException: com.example.worktime.MainActivity cannot be cast to android.app.TimePickerDialog$OnTimeSetListener

这是ClassCastException，因为

return new TimePickerDialog(getActivity(), (TimePickerDialog.OnTimeSetListener) getActivity(), hour, minute, DateFormat.is24HourFormat(getActivity()));

您在此处使用的上下文属于MainActivity

在MainActivity中实现TimePickerDialog.OnTimeSetListener将解决您的问题。

当其他片段中的按钮尝试打开应用程序时，时间选择器对话框使应用程序崩溃

2 个答案: