Method.invoke throws java.lang.IllegalArgumentException: wrong number of arguments


Above Java code is an unit test case, it uses reflection to get the private method downloadFile of class ZhangyoobaoLeshuaMerchantRegister, and set the access level of this method to public, then call it with parameters.

But running this line  result = method.invoke(register, null);  will got following error


The method signature of


To fix this issue, change following line