import java.lang.reflect.*;
public class Foo {
public void bar(int param){
System.out.println(param);
}
public static void main(String args[]){
Object f = new Foo();
try {
Method m = f.getClass().getMethod("bar", int.class);
m.invoke(f, 42);
} catch (Exception e){
System.err.println(e);
}
}
}
$ java Foo
42