Button onClick的NoSuchMethod异常

Question

我有一个正在测试JNI库的Android应用程序.该应用程序有一个带有onClick处理程序的按钮:

<RelativeLayout
    ...
    <Button
        ...
        android:id="@+id/btnGenerate"           
        android:text="@string/btn_generate"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:onClick="btnGenerate_onClick"/>
</RelativeLayout>

然后,在主要活动中:

public class MainActivity extends Activity {
    ...

    protected void btnGenerate_onClick(View view)
    {
        // Do some work...
        String str = <some result>; 

        final TextView lblNumbers = (TextView)findViewById(R.id.lblNumbers);
        if(lblNumbers != null)
        {
            lblNumbers.setText(str);
        }
    }
}

当我点击按钮时,我会收到一个NoSuchMethodException.

我从Android Button setOnClickListener设计帮助解除了解决方案,所以我不确定它为什么不起作用.

为什么代码导致NoSuchMethod异常？

---

09-05 07:20:57.417: W/dalvikvm(10563): threadid=1: thread exiting with uncaught exception (group=0x40aae228)
09-05 07:20:57.437: E/AndroidRuntime(10563): FATAL EXCEPTION: main
09-05 07:20:57.437: E/AndroidRuntime(10563): java.lang.IllegalStateException: Could not find a method btnGenerate_onClick(View) in the activity class com.cryptopp.prng.MainActivity for onClick handler on view class android.widget.Button with id 'btnGenerate'
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.view.View$1.onClick(View.java:3069)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.view.View.performClick(View.java:3549)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.view.View$PerformClick.run(View.java:14393)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.os.Handler.handleCallback(Handler.java:605)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.os.Handler.dispatchMessage(Handler.java:92)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.os.Looper.loop(Looper.java:154)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.app.ActivityThread.main(ActivityThread.java:4945)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at java.lang.reflect.Method.invokeNative(Native Method)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at java.lang.reflect.Method.invoke(Method.java:511)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at dalvik.system.NativeStart.main(Native Method)
09-05 07:20:57.437: E/AndroidRuntime(10563): Caused by: java.lang.NoSuchMethodException: btnGenerate_onClick [class android.view.View]
09-05 07:20:57.437: E/AndroidRuntime(10563):    at java.lang.Class.getConstructorOrMethod(Class.java:460)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at java.lang.Class.getMethod(Class.java:915)
09-05 07:20:57.437: E/AndroidRuntime(10563):    at android.view.View$1.onClick(View.java:3062)
09-05 07:20:57.437: E/AndroidRuntime(10563):    ... 11 more

Answer 1

该方法应该是public从外面可以看到的.

编辑:这是用于处理onClick属性的Android源代码- 链接

在那里,你可以看到它试图让您为通过该属性的值传递的方法getClass().getMethod()上Context对象.

getMethod由Oracle站点判断"返回一个Method对象,它反映了由此Class对象表示的类或接口的指定公共成员方法",因此该方法必须是public.