DatePickerDialog崩溃

Question

我是一个Android新手...

这是我的代码：

final Button taskDateButton = (Button)findViewById(R.id.taskTimeButton);
taskDateButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        DatePickerDialog datePickerDialog = new DatePickerDialog(TaskActivity.this, new DatePickerDialog.OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {

                taskDateCalendar.set(Calendar.YEAR, year);
                taskDateCalendar.set(Calendar.MONTH, monthOfYear);
                taskDateCalendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
                taskDate = taskDateCalendar.getTime();
                setDateButtonsWithDates();
                TimePickerDialog timePickerDialog = new TimePickerDialog(TaskActivity.this, new TimePickerDialog.OnTimeSetListener() {
                    @Override
                    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                        taskDateCalendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
                        taskDateCalendar.set(Calendar.MINUTE, minute);
                        taskDate = taskDateCalendar.getTime();
                        setDateButtonsWithDates();
                    }
                }, taskDateCalendar.get(Calendar.HOUR_OF_DAY), taskDateCalendar.get(Calendar.MINUTE), false);
                timePickerDialog.show();

            }
        }, taskDateCalendar.get(Calendar.YEAR), taskDateCalendar.get(Calendar.MONTH), taskDateCalendar.get(Calendar.DAY_OF_MONTH));
        datePickerDialog.show();


    }
});

加载DatePickerDialog时似乎崩溃了，特别是在这一行：

DatePickerDialog datePickerDialog = new DatePickerDialog(TaskActivity.this, new DatePickerDialog.OnDateSetListener() {

我环顾四周，但看不出是什么导致了这一点。

这是我得到的错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.Calendar.get(int)' on a null object reference

任何帮助？

由于

Answer 1

您的taskDateCalendar永远不会被初始化。

在使用之前尝试添加taskDateCalendar = Calendar.getInstance();。

Answer 2

您的taskDateCalendar对象似乎为空。在taskDateCalendar = Calendar.getInstance()之前致电taskDateCalendar.set(Calendar.YEAR, year)。