找不到PreferenceScreen类

Question

我在preferences.xml里有这个

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

    <CheckBoxPreference
        android:key="displayNotification"
        android:title="Display notification"
        />

    <ListPreference
        android:entries="@array/languages"
        android:key="language"
        />
</PreferenceScreen>

PreferencesActivity.java，使用此xml的类。

public class PreferencesActivity extends PreferenceActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.xml.preferences);
    }
}

我在载货单上这样声明

<activity android:name="com.tellthetime.PreferencesActivity" />

当我开始这个活动时，我得到了一个类找不到的异常，我不明白。

05-17 00:35:13.633: ERROR/AndroidRuntime(212): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tellthetime/com.tellthetime.PreferencesActivity}: android.view.InflateException: Binary XML file line #2: Error inflating class PreferenceScreen
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread.access$2200(ActivityThread.java:119)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.os.Looper.loop(Looper.java:123)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread.main(ActivityThread.java:4363)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at java.lang.reflect.Method.invokeNative(Native Method)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at java.lang.reflect.Method.invoke(Method.java:521)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at dalvik.system.NativeStart.main(Native Method)
05-17 00:35:13.633: ERROR/AndroidRuntime(212): Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class PreferenceScreen
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:576)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.inflate(LayoutInflater.java:385)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:198)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.Activity.setContentView(Activity.java:1622)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at com.tellthetime.PreferencesActivity.onCreate(PreferencesActivity.java:13)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     ... 11 more
05-17 00:35:13.633: ERROR/AndroidRuntime(212): Caused by: java.lang.ClassNotFoundException: android.view.PreferenceScreen in loader dalvik.system.PathClassLoader@44c067e8
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at java.lang.ClassLoader.loadClass(ClassLoader.java:573)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at java.lang.ClassLoader.loadClass(ClassLoader.java:532)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.createView(LayoutInflater.java:466)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.onCreateView(LayoutInflater.java:544)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:66)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563)
05-17 00:35:13.633: ERROR/AndroidRuntime(212):     ... 19 more

已经有人问过here了，但是没有人回答。正如Heiko Rupp在那个帖子中指出的那样，安卓正在寻找android.view包中的类，但这个类是在android.preferences中，这真的让我迷惑了。

Answer 1

您弄糊涂了，您试图将首选项定义设置为布局定义。首先设置Activity的布局，然后绑定您的首选项XML：

  ...
  setContentView(R.layout.layout);
  addPreferencesFromResource(R.xml.preferences);
  ...

Answer 2

"addPrerencesFromResource(R.**.yourPreference);“setContentView不是为PreferenceScreen准备的，而是为well准备的。yourPreference视图的活动应该继承PreferenceActivity，而不是Activity。

Answer 3

在PreferenceActivity中不需要setContentView()方法。

public class PreferencesActivity extends PreferenceActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);
   }
}

尽管它已被弃用。请改用Preference Fragments。