Android Preference Key关键字问题
今天在Preference.xml中添加Preference时将其中一个key设置为visible_pic，结果在调试时一直报错，错误如下：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.n2hsu.doplus.weibo/com.n2hsu.doplus.weibo.activity.Setting}: java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:205)
at android.preference.Preference.getPersistedString(Preference.java:1406)
at android.preference.ListPreference.onSetInitialValue(ListPreference.java:278)
at android.preference.Preference.dispatchSetInitialValue(Preference.java:1322)
at android.preference.Preference.onAttachedToHierarchy(Preference.java:1134)
at android.preference.PreferenceGroup.addPreference(PreferenceGroup.java:163)
at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:104)
at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:45)
at android.preference.GenericInflater.rInflate(GenericInflater.java:488)
at android.preference.GenericInflater.rInflate(GenericInflater.java:493)
at android.preference.GenericInflater.inflate(GenericInflater.java:326)
at android.preference.GenericInflater.inflate(GenericInflater.java:263)
at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:269)
at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:1418)
at com.n2hsu.doplus.weibo.activity.Setting.onCreate(Setting.java:64)
at android.app.Activity.performCreate(Activity.java:5008)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
... 11 more
如上所述，说是某处无法将Boolean类型转换为String，但是这个key是写在XML中的，所以错误只能出现在XML硬转码为代码的过程中，其间想通过源码做调试，不成功。在测试时，我在visible前后加个字符都不会出现上述错误。
所以可能的原因有两个：
visible可能在Preference key的转码过程中是关键字；在SharedPreference的XML中visible是关键字。
真实原因还有待查看。