Android DatePicker.OnDateChangedListener 调用了两次

DatePicker.OnDateChangedListener called twice

提问by tomor

I'm trying to create an app where the user selects a date from a DatePicker, and then a list is updated with some values.

我正在尝试创建一个应用程序，用户从 DatePicker 中选择一个日期，然后用一些值更新一个列表。

My GUI looks like this:

我的 GUI 看起来像这样：

    <LinearLayout
    android:id="@+id/linearLayout1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center" >


    <DatePicker
        android:id="@+id/datePicker"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

<LinearLayout
    android:id="@+id/linearLayout2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >



   <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1" >


    </ListView> 
</LinearLayout>

Whereas my DatePicker initialization and handling look as follows:

而我的 DatePicker 初始化和处理如下所示：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    datePicker = (DatePicker) findViewById(R.id.datePicker);

    Calendar c = Calendar.getInstance();

    year = c.get(Calendar.YEAR);
    month = c.get(Calendar.MONTH);
    day = c.get(Calendar.DAY_OF_MONTH);

    datePicker.init(year, month, day, dateSetListener);
}

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {

    public void onDateChanged(DatePicker view, int year, int monthOfYear,
            int dayOfMonth) {
         Calendar c = Calendar.getInstance();
         c.set(year, monthOfYear, dayOfMonth);
         System.out.println ("TEST");

    }
};

In CatLog I see that "TEST" string is output twice, each time I play with the +/- buttons on the widget. What could be the problem?

在 CatLog 中，我看到“TEST”字符串输出两次，每次我玩小部件上的 +/- 按钮时。可能是什么问题呢？

Note: I've "disabled" the list-updating code on purpose, in order to make sure that the problem is not related to the ListView, as in here

注：我“已禁用”的列表更新的用途代码，以确保该问题不涉及到ListView，在这里

回答by Cesardl

When I test my application, method onDateSet called twice after accept the date selection and once when I canceled.

当我测试我的应用程序时，方法 onDateSet 在接受日期选择后调用了两次，在我取消时调用了一次。

I added a validation in the method onDateSet with parameter view, something like this

我在带有参数视图的方法 onDateSet 中添加了一个验证，就像这样

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth){
    if (view.isShown()) {
        updateDate(year, monthOfYear, dayOfMonth);
    }
}

I hope you serve

我希望你服务

回答by tomor

I still haven't managed to find a neat fix. I've rather found a workaround, so the event does not fire twice. The workaround is as follows:

我仍然没有设法找到一个巧妙的解决办法。我宁愿找到一种解决方法，因此该事件不会触发两次。解决方法如下：

int timesCalled = 1;

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {

public void onDateChanged(DatePicker view, int year, int monthOfYear,
        int dayOfMonth) {
     Calendar c = Calendar.getInstance();
     c.set(year, monthOfYear, dayOfMonth);
     timesCalled += 1;

     if ((timesCalled % 2) == 0) {
        System.out.println ("TEST");
     }

}};

回答by evgeny.myasishchev

Instead of the onDateSet callback I've overridden onClick method of the DatePickerDialog dialog and handle BUTTON_POSITIVE clicks only.

我覆盖了 DatePickerDialog 对话框的 onClick 方法，而不是 onDateSet 回调，并且只处理 BUTTON_POSITIVE 点击。

public static class DatePickerFragment extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Calendar c = Calendar.getInstance();
        int initialYear = c.get(Calendar.YEAR);
        int initialMonth = c.get(Calendar.MONTH);
        int initialDay = c.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), null, initialYear, initialMonth, initialDay) {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                if (which == BUTTON_POSITIVE) {
                    int year = getDatePicker().getYear();
                    int month = getDatePicker().getMonth();
                    int day = getDatePicker().getDayOfMonth();

                    //TODO: Do your logic here
                }
                super.onClick(dialog, which);
            }
        };
    }
}

The code stays clear but still it's not clear why onDateSet is called twice.

代码保持清晰，但仍然不清楚为什么 onDateSet 被调用两次。

回答by Graeme

Perhaps modify the listener by adding instance variables, that way you can check to see if they are different from the last time the method was called:

也许通过添加实例变量来修改侦听器，这样您就可以检查它们是否与上次调用该方法时不同：

final DatePickerDialog datePickerDialog = new DatePickerDialog (this, new DatePickerDialog.OnDateSetListener()
    {   
        private int year;
        private int month;
        private int day;

        @Override
        public void onDateSet (DatePicker view, int year, int monthOfYear, int dayOfMonth)
        {
            if (this.year == year && this.month == monthOfYear && this.day == dayOfMonth)
                return;

            this.year = year;
            this.month = monthOfYear;
            this.day = dayOfMonth;

            calendar.set (year, month, day);
            int index = officeCalendar.indexOfKey (calendar.getTimeInMillis ());

            if (index > -1)
                viewPager.setCurrentItem (index);
        }
    }, calendar.get (Calendar.YEAR), calendar.get (Calendar.MONTH), calendar.get (Calendar.DATE));

回答by user1640247

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() { 

    public void onDateChanged(DatePicker view, int year, int monthOfYear, 
            int dayOfMonth) { 
         Calendar c = Calendar.getInstance(); 
         c.set(year, monthOfYear, dayOfMonth); 
         updateDisplay();

    } 
}; 


TextView datetext;
datetext = (TextView) findViewById(R.id.selected_date);


private void updateDisplay() {
        this.datetext.setText(new StringBuilder()
                // Month is 0 based so add 1
                .append(mMonth + 1).append("-").append(mDay).append("-")
                .append(mYear).append(" "));
    }

回答by Nguy?n V?n ???c

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {
    boolean fired = false;
    public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
         if (fired == true){
//Twince
         }
         else{
             Calendar c = Calendar.getInstance();
             c.set(year, monthOfYear, dayOfMonth);
             System.out.println ("TEST");
         }

    }
};

回答by iamronak

Please check my answer over here. It is for TimePickerDialog but also applicable for DatePickerDialog. You can create a custom dialog, it's almost equally as fast and simple and just works.

请检查我的答案在这里。它适用于 TimePickerDialog 但也适用于 DatePickerDialog。您可以创建一个自定义对话框，它几乎同样快速、简单且有效。

https://stackoverflow.com/a/25672760/940450

https://stackoverflow.com/a/25672760/940450

回答by user3922209

Not necessary to add this code under Jelly beans

无需在果冻豆下添加此代码

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth){
    if (view.isShown()) {
        updateDate(year, monthOfYear, dayOfMonth);
    }
}