DatePicker.OnDateChangedListener 调用了两次

Question

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

我的 GUI 如下所示：

    <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>

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");

    }
};

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

注意：我故意“禁用”了列表更新代码，以确保问题与 ListView 无关，如here

Answer 1

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。

我在 onDateSet 方法中添加了一个带有参数视图的验证，类似这样

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

我希望你服务

Answer 2

我还没有设法找到一个巧妙的解决方法。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");
     }

}};

Answer 3

我重写了 DatePickerDialog 对话框的 onClick 方法，而不是 onDateSet 回调，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);
            }
        };
    }
}

代码保持清晰，但仍不清楚为什么 onDateSet 被调用两次。

Answer 4

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(" "));
    }

Answer 5

也许可以通过添加实例变量来修改监听器，这样你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));

Answer 6

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");
         }

    }
};

Answer 7

请在此处查看我的答案。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

Answer 8

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);
    }
}

Answer 9

我创建了一个 SupportDatePickerDialog.kt 类

    import android.app.DatePickerDialog
    import android.content.Context
    import android.os.Build
    import android.widget.DatePicker
    import androidx.appcompat.view.ContextThemeWrapper
    
    /**
     * Support [DatePickerDialog]
     * for working around Samsung 5 [java.util.IllegalFormatConversionException] bug.
     * > Fatal Exception: java.util.IllegalFormatConversionException: %d can't format java.lang.String arguments
     * http://stackoverflow.com/a/31855744/570168
     * for OnDateSetListener called twice bug
     * https://stackoverflow.com/questions/12436073/datepicker-ondatechangedlistener-called-twice
     *
     */
    
    
    
    class SupportDateSetListener(private val function: (DatePicker, Int, Int, Int) -> Unit) : DatePickerDialog.OnDateSetListener {
        override fun onDateSet(view: DatePicker, year: Int, month: Int, dayOfMonth: Int) {
            if (view.isShown) {
                function.invoke(view, year, month, dayOfMonth)
            }
        }
    }
    
    class SupportDatePickerDialog(context: Context, listener: SupportDateSetListener, year: Int, month: Int, dayOfMonth: Int) : DatePickerDialog(fixContext(context), listener, year, month, dayOfMonth) {
        companion object {
            /**
             * Wraps the [Context] to use the holo theme to avoid stupid bug on Samsung devices.
             */
            @Suppress("DEPRECATION")
            private fun fixContext(context: Context): Context {
                return if (isBrokenSamsungDevice) {
                    ContextThemeWrapper(context, android.R.style.Theme_Holo_Light_Dialog)
                } else {
                    context
                }
            }
    
            /**
             * Affected devices:
             * - Samsung 5.0
             * - Samsung 5.1
             *
             * @return true if device is affected by this bug.
             */
            @Suppress("SpellCheckingInspection")
            private val isBrokenSamsungDevice: Boolean
                get() = (Build.MANUFACTURER.equals("samsung", ignoreCase = true)
                        && Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP_MR1)
        }
    }

用法：

val calendar = Calendar.getInstance()
val supportDatePickerDialog = SupportDatePickerDialog(this, SupportDateSetListener { datePicker: DatePicker, year: Int, month: Int, dayOfMonth: Int ->
    //TODO
}, calendar[Calendar.YEAR], calendar[Calendar.MONTH], calendar[Calendar.DAY_OF_MONTH])

supportDatePickerDialog.show()