从preferenceActivity ClassCastException异常 [英] ClassCastException from a PreferenceActivity

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本文介绍了从preferenceActivity ClassCastException异常的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我每一次我尝试使用这个preference类得到一个ClassCastException,我想不通这是为什么。任何帮助将是非常美联社preciated。该行崩溃是添加preferencesFromResources 命令。

 进口android.os.Bundle;
。进口的Andr​​oid preference preferenceActivity;


公共类preferenceManager扩展preferenceActivity {
    @燮pressWarnings(德precation)
    @覆盖
    保护无效的onCreate(包savedInstanceState){
        // TODO自动生成方法存根
        super.onCreate(savedInstanceState);
        加preferencesFromResource(R.xml preferences。); //此行崩溃
    }
}
 

preference.xml

 < XML版本=1.0编码=UTF-8&GT?;
< preference的xmlns:机器人=htt​​p://schemas.android.com/apk/res/android>
                <复选框preference
                        机器人:标题=@字符串/ startAnimation
                        安卓:设置defaultValue =真
                        机器人:总结=@字符串/ startAnimationDescription
                        机器人:关键=startAnimation/>

< / preference>
 

堆栈跟踪

  11-18 19:04:19.165:E / AndroidRuntime(1362):未捕获的处理程序:螺纹主力退出,由于未捕获的异常
11-18 19:04:19.175:E / AndroidRuntime(1362):java.lang.RuntimeException的:无法启动的活动ComponentInfo{com.pearsonartphoto.psychictester/com.pearsonartphoto.psychictester.$p$pferenceManager}: java.lang.ClassCastException:。安卓preference preference
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread.access $ 2200(ActivityThread.java:119)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1863)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.os.Handler.dispatchMessage(Handler.java:99)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.os.Looper.loop(Looper.java:123)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread.main(ActivityThread.java:4363)
11-18 19:04:19.175:E / AndroidRuntime(1362):在java.lang.reflect.Method.invokeNative(本机方法)
11-18 19:04:19.175:E / AndroidRuntime(1362):在java.lang.reflect.Method.invoke(Method.java:521)
11-18 19:04:19.175:E / AndroidRuntime(1362):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:860)
11-18 19:04:19.175:E / AndroidRuntime(1362):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
11-18 19:04:19.175:E / AndroidRuntime(1362):在dalvik.system.NativeStart.main(本机方法)
11-18 19:04:19.175:E / AndroidRuntime(1362):java.lang.ClassCastException::所致。安卓preference preference
11-18 19:04:19.175:E / AndroidRuntime(1362):在安卓preference.GenericInflater.inflate(GenericInflater.java:320)
11-18 19:04:19.175:E / AndroidRuntime(1362):在安卓preference.GenericInflater.inflate(GenericInflater.java:263)
11-18 19:04:19.175:E / AndroidRuntime(1362):在安卓preference preferenceManager.inflateFromResource(preferenceManager.java:254)。
11-18 19:04:19.175:E / AndroidRuntime(1362):在安卓preference preferenceActivity.add preferencesFromResource(preferenceActivity.java:253)。
11-18 19:04:19.175:E / AndroidRuntime(1362):在com.pearsonartphoto.psychictester preferenceManager.onCreate(preferenceManager.java:12)。
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-18 19:04:19.175:E / AndroidRuntime(1362):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
11-18 19:04:19.175:E / AndroidRuntime(1362):11 ...更多
 

解决方案

XML文件的顶级元素应该是preferenceScreen没有preference

 < XML版本=1.0编码=UTF-8&GT?;
< preferenceScreen的xmlns:机器人=htt​​p://schemas.android.com/apk/res/android>
    <复选框preference
        机器人:关键=pref_sync
        机器人:标题=@字符串/ pref_sync
        机器人:总结=@字符串/ pref_sync_summ
        安卓:设置defaultValue =真/>
    <表preference
        机器人:依赖=pref_sync
        机器人:关键=pref_syncConnectionType
        机器人:标题=@字符串/ pref_syncConnectionType
        机器人:dialogTitle =@字符串/ pref_syncConnectionType
        机器人:项=@阵列/ pref_syncConnectionTypes_entries
        机器人:entryValues​​ =@阵列/ pref_syncConnectionTypes_values​​
        安卓:设置defaultValue =@字符串/ pref_syncConnectionTypes_default/>
< / preferenceScreen>
 

从设置文档 <提取/ P>

I'm getting a classCastException every time I try to use this preference class, and I can't figure out why. Any help would be much appreciated. The line the crashes is the addPreferencesFromResources command.

import android.os.Bundle;
import android.preference.PreferenceActivity;


public class PreferenceManager extends PreferenceActivity {
    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences); // This line crashes
    }
}

preference.xml

<?xml version="1.0" encoding="utf-8"?>
<Preference xmlns:android="http://schemas.android.com/apk/res/android" >
                <CheckBoxPreference
                        android:title="@string/startAnimation"
                        android:defaultValue="true"
                        android:summary="@string/startAnimationDescription"
                        android:key="startAnimation" />    

</Preference>

Stack Trace

11-18 19:04:19.165: E/AndroidRuntime(1362): Uncaught handler: thread main exiting due to uncaught exception
11-18 19:04:19.175: E/AndroidRuntime(1362): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pearsonartphoto.psychictester/com.pearsonartphoto.psychictester.PreferenceManager}: java.lang.ClassCastException: android.preference.Preference
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread.access$2200(ActivityThread.java:119)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.os.Looper.loop(Looper.java:123)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread.main(ActivityThread.java:4363)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at java.lang.reflect.Method.invokeNative(Native Method)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at java.lang.reflect.Method.invoke(Method.java:521)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at dalvik.system.NativeStart.main(Native Method)
11-18 19:04:19.175: E/AndroidRuntime(1362): Caused by: java.lang.ClassCastException: android.preference.Preference
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.preference.GenericInflater.inflate(GenericInflater.java:320)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.preference.GenericInflater.inflate(GenericInflater.java:263)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:254)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:253)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at com.pearsonartphoto.psychictester.PreferenceManager.onCreate(PreferenceManager.java:12)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-18 19:04:19.175: E/AndroidRuntime(1362):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
11-18 19:04:19.175: E/AndroidRuntime(1362):     ... 11 more

解决方案

The top element of the xml file should be PreferenceScreen not Preference

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <CheckBoxPreference
        android:key="pref_sync"
        android:title="@string/pref_sync"
        android:summary="@string/pref_sync_summ"
        android:defaultValue="true" />
    <ListPreference
        android:dependency="pref_sync"
        android:key="pref_syncConnectionType"
        android:title="@string/pref_syncConnectionType"
        android:dialogTitle="@string/pref_syncConnectionType"
        android:entries="@array/pref_syncConnectionTypes_entries"
        android:entryValues="@array/pref_syncConnectionTypes_values"
        android:defaultValue="@string/pref_syncConnectionTypes_default" />
</PreferenceScreen>

Extracted from the settings documentation

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