DatePicker.OnDateChangedListener被调用两次 [英] DatePicker.OnDateChangedListener called twice

问题描述

我正在尝试创建一个应用程序，用户从DatePicker中选择一个日期，然后使用某些值更新列表。

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：

Whereas my DatePicker initialization and handling look as follows:

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，每次我玩+ - 小部件上的按钮。可能是什么问题？

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?

注意：为了确保问题与ListView，如此处

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

推荐答案

当我测试我的应用程序时，方法onDateSet在接受日期选择后调用两次，当我取消时，会调用一次。

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

我在参数视图的方法onDateSet中添加了一个验证，像这样

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

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

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