How do I invoke a Java method when given the method name as a string?

Question

If I have two variables:

Object obj;
String methodName = \"getName\";

Without knowing the class of obj, how can I call the met

Answer 1

If you do the call several times you can use the new method handles introduced in Java 7. Here we go for your method returning a String:

Object obj = new Point( 100, 200 );
String methodName = "toString";  
Class resultType = String.class;

MethodType mt = MethodType.methodType( resultType );
MethodHandle methodHandle = MethodHandles.lookup().findVirtual( obj.getClass(), methodName, mt );
String result = resultType.cast( methodHandle.invoke( obj ) );

System.out.println( result );  // java.awt.Point[x=100,y=200]