我试图以不同方式自定义警报对话框的两个按钮。通过在样式中使用android:layout，我更改了对话框的默认布局。我将此参数重定向到我的项目中的布局，其中包含与AlertDialog布局完全相同的源代码。但是在执行应用程序时，由于NullPointerExceptoin
Style.xml
<style name="AppTheme" parent="android:Theme.Holo">
<!-- Customize your theme here. -->
<item name="android:alertDialogStyle">@style/test_style</item>
<item name="android:alertDialogTheme">@style/test_style</item>
</style>
<style name="test_style" >
<item name="android:layout">@layout/view_dialog_base</item>
</style>
view_dialog_base.xml
<?xml version="1.0" encoding="utf-8"?>
<!--
/*
** Copyright 2010, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
-->
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/parentPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dip"
android:layout_marginEnd="8dip"
android:orientation="vertical">
<LinearLayout android:id="@+id/topPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<View android:id="@+id/titleDividerTop"
android:layout_width="match_parent"
android:layout_height="2dip"
android:visibility="gone"
android:background="@android:color/holo_blue_light" />
<LinearLayout android:id="@+id/title_template"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:gravity="center_vertical|start"
android:minHeight="@dimen/alert_dialog_title_height"
android:layout_marginStart="16dip"
android:layout_marginEnd="16dip">
<ImageView android:id="@+id/icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingEnd="8dip"
android:src="@null" />
<com.android.internal.widget.DialogTitle android:id="@+id/alertTitle"
style="?android:attr/windowTitleStyle"
android:singleLine="true"
android:ellipsize="end"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAlignment="viewStart" />
</LinearLayout>
<View android:id="@+id/titleDivider"
android:layout_width="match_parent"
android:layout_height="2dip"
android:visibility="gone"
android:background="@android:color/holo_blue_light" />
<!-- If the client uses a customTitle, it will be added here. -->
</LinearLayout>
<LinearLayout android:id="@+id/contentPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:orientation="vertical"
android:minHeight="64dp">
<ScrollView android:id="@+id/scrollView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clipToPadding="false">
<TextView android:id="@+id/message"
style="?android:attr/textAppearanceMedium"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingStart="16dip"
android:paddingEnd="16dip"
android:paddingTop="8dip"
android:paddingBottom="8dip"/>
</ScrollView>
</LinearLayout>
<FrameLayout android:id="@+id/customPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:minHeight="64dp">
<FrameLayout android:id="@+android:id/custom"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</FrameLayout>
<LinearLayout android:id="@+id/buttonPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="@dimen/alert_dialog_button_bar_height"
android:orientation="vertical"
android:divider="?android:attr/dividerHorizontal"
android:showDividers="beginning"
android:dividerPadding="0dip">
<LinearLayout
style="?android:attr/buttonBarStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layoutDirection="locale"
android:measureWithLargestChild="true">
<Button android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_gravity="start"
android:layout_weight="1"
android:maxLines="2"
style="?android:attr/buttonBarButtonStyle"
android:textSize="14sp"
android:minHeight="@dimen/alert_dialog_button_bar_height"
android:layout_height="wrap_content" />
<Button android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_weight="1"
android:maxLines="2"
style="?android:attr/buttonBarButtonStyle"
android:textSize="14sp"
android:minHeight="@dimen/alert_dialog_button_bar_height"
android:layout_height="wrap_content" />
<Button android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_gravity="end"
android:layout_weight="1"
android:maxLines="2"
android:minHeight="@dimen/alert_dialog_button_bar_height"
style="?android:attr/buttonBarButtonStyle"
android:textSize="14sp"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>
崩溃时获得的logcat消息是
java.lang.NullPointerException
at com.android.internal.app.AlertController.setupContent(AlertController.java:502)
at com.android.internal.app.AlertController.setupView(AlertController.java:395)
at com.android.internal.app.AlertController.installContent(AlertController.java:241)
at android.app.AlertDialog.onCreate(AlertDialog.java:337)
at android.app.Dialog.dispatchOnCreate(Dialog.java:361)
at android.app.Dialog.show(Dialog.java:262)