findViewById返回null preference布局 [英] findViewById returns null for preference layout

问题描述

我有一个preference屏幕（responder_generic.xml）如下：

I have a preference screen (responder_generic.xml) as follows:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

    <Preference
        android:defaultValue="false"
        android:key="auto_responder_key"
        android:layout="@layout/preference_header_switch_item_responder"
        android:title="@string/auto_responder">
    </Preference>

</PreferenceScreen>

对此我实例如下：（2.3.3版本）

which i am instantiating as follows : (in version 2.3.3)

addPreferencesFromResource(R.xml.responder_generic);

和我的布局= preference_header_switch_item_responder 看起来如下：

and my layout = preference_header_switch_item_responder looks as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- Layout of a header item in PreferenceActivity. -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="33dp"
    android:gravity="center_vertical"
    android:minHeight="33dp"
    android:id="@+id/preference_header_switch_item_responder"
    style="?android:attr/listSeparatorTextViewStyle" >

    <RelativeLayout
        android:layout_width="0dip"
        android:layout_height="wrap_content"
        android:layout_marginLeft="5dp"
        android:layout_weight="1" >

        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ellipsize="marquee"
            android:fadingEdge="horizontal"
            android:singleLine="true"
            android:text="@string/auto_responder"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/summary"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@android:id/title"
            android:ellipsize="end"
            android:textAppearance="?android:attr/textAppearanceSmall" />
    </RelativeLayout>

    <include layout="@layout/compound_button" />

</LinearLayout>

现在，我有中定义的化合物，按钮布局文件夹和布局/ V-14 如下分别为：

Now, i have the compound button defined in layout folder and layout/v-14 respectively as follows :

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" >

<CheckBox
    android:id="@+id/switchWidget"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:clickable="true"
    android:focusable="false"
    android:padding="8dip"
    android:layout_marginRight="14dip" />

</merge>

和

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <Switch
        android:id="@+id/switchWidget"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:clickable="true"
        android:focusable="false"
        android:padding="8dip" 
        android:layout_marginRight="14dip"/>

</merge>

在 onPostCreate 的方法，我想找到使用 findViewById（R.id.switchWidget）在此复选框/在运行时切换，但它总是返回null。

In the onPostCreate method, i am trying to find the this checkbox/switch at run time using findViewById(R.id.switchWidget) but its always returning null.

任何想法可能是什么原因？

Any idea what could be the reason ?

推荐答案

原因是我是添加多个preferences到屏幕上，因此，我不得不求助于添加自定义preference。详细的解决方案已经在以下链接提供了：

Reason was i was adding multiple preferences to the screen, hence, i had to resort to adding a custom preference. Detailed solution has been provided in the following link:

该解决方案在下面的链接被提供。

The solution has been provided in the following link.

<一个href=\"http://stackoverflow.com/questions/15728192/usage-of-findviewbyid-in-$p$pferenceactivity\">usage findviewbyid在preferenceactivity

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