Invoke method with an Object List

Question

This code allow me invoking a method with tests parameter

Method m = aClass.getDeclaredMethod(methodName, paramTypes);
Integer n =10;
Object retobj =m.invoke(o, "test",n);
System.out.println(retobj);

Now I want to invoke the method with the arguments list.

List<Object> arguments =container.getArgs();
Object retobj =m.invoke(o, (Object) arguments);

But I get this error

java.lang.IllegalArgumentException: wrong number of arguments

Spend some time in reading [Oracle Tutorial -Invoking Methods](http://docs.oracle.com/javase/tutorial/reflect/member/methodInvocation.html) — Braj, Jul 11 '14 at 19:33

score 1 · Accepted Answer · answered Jul 11 '14 at 19:19

The invoke method takes two parameters: the object on which to invoke the method, and a "varargs" parameter to hold the arguments.

Such a parameter (also "variable arity") is interchangeable with an array, and it's treated as an array in the body of such a method.

Convert your List<Object> to an array, then pass it in.

Object retobj = m.invoke(o, arguments.toArray());

score 0 · Answer 2 · answered Jul 11 '14 at 19:20

0

In the first invoke call, you are passing 2 arguments, in the second invoke, you are only passing 1.

answered Jul 11 '14 at 19:20

Jamie Cockburn

2 Answers2