android Class.forName拋出異常

-5

我在Android項目中玩Java反射。android Class.forName拋出異常

源代碼：

Log.d("LOG", "begin"); 
try { 
    final android.view.View.OnSystemUiVisibilityChangeListener unusedVar = new android.view.View.OnSystemUiVisibilityChangeListener() { 

     @Override 
     public void onSystemUiVisibilityChange(int visibility) { 
      // TODO Auto-generated method stub 

     } 
    }; 
    Log.d("LOG", "unusedVar is null = " + (unusedVar == null? "Yes": "No")); 
    Class newClass = Class.forName("android.view.View.OnSystemUiVisibilityChangeListener"); 
    Log.d("LOG", "newClass created"); 
} catch (Exception ex) { 
    Log.d("LOG", "Failed to create newClass", ex); 
} 
Log.d("LOG", "end");

上面的代碼中的onCreate（）我的活性。
該項目的構建目標是Android 4.0。
我在裝有Android 4.0.4的設備上運行它。

結果： 可變unusedVar是NOT null，但Class.forName拋出一個ClassNotFoundException。

登錄：

D/LOG(13205): begin 
D/LOG(13205): unusedVar is null = No 
D/LOG(13205): Failed to create newClass 
D/LOG(13205): java.lang.ClassNotFoundException: android.view.View.OnSystemUiVisibilityChangeListener 
D/LOG(13205): at java.lang.Class.classForName(Native Method) 
D/LOG(13205): at java.lang.Class.forName(Class.java:217) 
D/LOG(13205): at java.lang.Class.forName(Class.java:172) 
D/LOG(13205): at com.MyActivity.onCreate(VideoPlayerActivity.java:100) 
D/LOG(13205): at android.app.Activity.performCreate(Activity.java:4465) 
D/LOG(13205): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
D/LOG(13205): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
D/LOG(13205): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
D/LOG(13205): at android.app.ActivityThread.access$600(ActivityThread.java:123) 
D/LOG(13205): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
D/LOG(13205): at android.os.Handler.dispatchMessage(Handler.java:99) 
D/LOG(13205): at android.os.Looper.loop(Looper.java:137) 
D/LOG(13205): at android.app.ActivityThread.main(ActivityThread.java:4424) 
D/LOG(13205): at java.lang.reflect.Method.invokeNative(Native Method) 
D/LOG(13205): at java.lang.reflect.Method.invoke(Method.java:511) 
D/LOG(13205): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
D/LOG(13205): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
D/LOG(13205): at dalvik.system.NativeStart.main(Native Method) 
D/LOG(13205): Caused by: java.lang.NoClassDefFoundError: android/view/View/OnSystemUiVisibilityChangeListener 
D/LOG(13205): ... 18 more 
D/LOG(13205): Caused by: java.lang.ClassNotFoundException: android.view.View.OnSystemUiVisibilityChangeListener 
D/LOG(13205): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61) 
D/LOG(13205): at java.lang.ClassLoader.loadClass(ClassLoader.java:501) 
D/LOG(13205): at java.lang.ClassLoader.loadClass(ClassLoader.java:461) 
D/LOG(13205): ... 18 more 
D/LOG(13205): end

這是爲什麼？是因爲android.view.View.OnSystemUiVisibilityChangeListener是接口而不是類？

來源

2012-10-10 Pang

您可能需要使用java.lang.reflect.Proxy。看看這個：http://stackoverflow.com/questions/1082850/java-reflection-create-an-implementing-class – Naytzyrhc

接口OnSystemUiVisibilityChangeListener嵌套在類View，所以我相信你將不得不做Class.forName("android.view.View$OnSystemUiVisibilityChangeListener");（注意'$'）。

參考文獻：

來源

2012-10-10 04:01:16

android Class.forName拋出異常

回答

相關問題