click the btn_scroll_left or btn_scroll_right error

[leiyuanhua]

E/AndroidRuntime( 1129): java.lang.IllegalStateException: Could not find a method previousScreen(View) in the activity class com.android.launcher.Launcher for onClick handler on view class android.widget.ImageView with id 'btn_scroll_left'
E/AndroidRuntime( 1129): at android.view.View$1.onClick(View.java:2059)
E/AndroidRuntime( 1129): at android.view.View.performClick(View.java:2408)
E/AndroidRuntime( 1129): at android.view.View$PerformClick.run(View.java:8816)
E/AndroidRuntime( 1129): at android.os.Handler.handleCallback(Handler.java:587)
E/AndroidRuntime( 1129): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime( 1129): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 1129): at android.app.ActivityThread.main(ActivityThread.java:4627)
E/AndroidRuntime( 1129): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 1129): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime( 1129): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)
E/AndroidRuntime( 1129): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
E/AndroidRuntime( 1129): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 1129): Caused by: java.lang.NoSuchMethodException: previousScreen
E/AndroidRuntime( 1129): at java.lang.ClassCache.findMethodByName(ClassCache.java:308)
E/AndroidRuntime( 1129): at java.lang.Class.getMethod(Class.java:985)
E/AndroidRuntime( 1129): at android.view.View$1.onClick(View.java:2052)
E/AndroidRuntime( 1129): ... 11 more
W/ActivityManager( 138): Force finishing activity com.android.launcher/.Launcher