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POHow to invoke a underlying void method using method handle class in java 7?
 

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  1. POHow to invoke a underlying void method using method handle class in java 7?
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    <p>I'm trying to play with MethodHandles in Java 7.</p> <p>I have a class here:</p> <pre><code>public class TestCase { MethodType mt; public static void main(String args[]) { Android a = new Android(); MethodHandleExample.doSomething(a); } } class Android { public void thisIsMagic() { System.out.println("Might be called from the method handel"); } } </code></pre> <p>And the method handle example calls are here in this class:</p> <pre><code>public class MethodHandleExample { public static void doSomething(Object obj) { MethodHandle methodHandle = null ; MethodType mt = MethodType.methodType(void.class); MethodHandles.Lookup lookup = MethodHandles.lookup(); try{ try { methodHandle = lookup.findVirtual(obj.getClass(),"thisIsMagic",mt); } catch (NoSuchMethodException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } catch (IllegalAccessException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } } finally { } try { methodHandle.invoke(); } catch (Throwable throwable) { throwable.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } } </code></pre> <p>}</p> <p>but when I try to run this code I get an exception like this:</p> <pre><code>java.lang.invoke.WrongMethodTypeException: cannot convert MethodHandle(Android)void to ()void at java.lang.invoke.MethodHandle.asType(MethodHandle.java:691) at java.lang.invoke.InvokeGeneric.dispatch(InvokeGeneric.java:103) at com.generic.exception.AnnotationParser.doSomething(AnnotationParser.java:35) at com.generic.exception.TestCase.main(TestCase.java:18) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) </code></pre> <p>The exception I'm getting is on the line :</p> <pre><code> methodHandle.invoke(); </code></pre> <p>Not sure how do I invoke the underlying method in this case.</p> <p>Thanks in advance.</p>
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    1. USsriram
    1. USsriram
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    1. COWhy are you writing your own class called `MethodHandle`?
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      1. USJim Garrison
    2. CO@JimGarrison: Sorry that was an typo it should be `MethodHandleExample`. And I edited the question too.
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      1. USsriram
 

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