Getting return value of a method in an interface

Hello! I have a problem. I have an interface called I. One of the declared method in this interface is M. And I have a class called C. Class C declares Interface I. I want to get the return value of the method M. I used invoke method. M.invoke(anInstance, arg[]). You can't take the instance of interfaces or abstract classes. If I use a class instead of instance for anInstance variable, i get "java.lang.IllegalArgumentException: object is not an instance of declaring class" error. If I use an instance, i get "java.lang.IllegalAccessException: Can not call newInstance() on the Class for java.lang.Class" error. This is because of getting an instance of an interface. if you can help me. i will be greatfully happy.

Thanks for the feedback Tom although you should rethink what you said.
I did not trash your suggestion, nor did I make any reference to it.
Perhaps you should read the OP to see where you went wrong.
OP wants to know return type of Interface's methodNo, the OP wants to obtain the return value.
AND OP knows that instantiation won't work.He was trying to instantiate an Interface, which is not possible. In order for him invoke a Method he needs a concrete implementation. I was simply pointing out what he needs to do in order to acheive his aim.
b) there may be no known implementing classes at
runtimeIf there is no implementing class provided then he will not be able to invoke a method on its instance.
c) even if there were such a class, instantiating it
may have unwanted side effects, takes unnecessary
timeWhy is that a problem? One reason for invoking M is to see what happens.
the class may have N methods while the interface
has only one, so you might look for the correct method
too longIf you bothered to study the code I supplied I obtain a Method from the Interface class so there is no problem in "looking" for a method, besides which there can be exactly 1 method with a given signature in any class so there is no searching involved.
On a personal note, such negative replies are neither helpful to the OP and can cause a credibility problem caused by being labelled a Troll.

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Hi Gregor,
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Lets take this slow and easy. First of all, you need to learn how to format your code for readability. Read and take to heart
{color:0000ff}http://java.sun.com/docs/codeconv/html/CodeConvTOC.doc.html{color}
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Do you know how to string Strings together? (it's called concatenation.) And how to represent a newline in a String literal?
db

Getting return value of a method in an interface

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