log信息如下

01-26 02:56:31.954      589-589/com.test.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main

    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.myapplication/com.test.myapplication.MainActivity}: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.ImageButton

            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)

            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)

            at android.app.ActivityThread.access$600(ActivityThread.java:122)

            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)

            at android.os.Handler.dispatchMessage(Handler.java:99)

            at android.os.Looper.loop(Looper.java:137)

            at android.app.ActivityThread.main(ActivityThread.java:4340)

            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:784)

            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)

            at dalvik.system.NativeStart.main(Native Method)

     Caused by: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.ImageButton

            at com.test.myapplication.MainActivity.onCreate(MainActivity.java:20)

            at android.app.Activity.performCreate(Activity.java:4465)

            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)

            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)

            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)

            at android.app.ActivityThread.access$600(ActivityThread.java:122)

            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)

            at android.os.Handler.dispatchMessage(Handler.java:99)

            at android.os.Looper.loop(Looper.java:137)

            at android.app.ActivityThread.main(ActivityThread.java:4340)

            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:784)

            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)

            at dalvik.system.NativeStart.main(Native Method)