java.lang.IllegalArgumentException: argument type mismatch on string array

Question

This is my code to invoke a method dynamically:

String[] parameters = new String[requiredParameters.length];
//here i put some values in the parameters array
method = TestRecommendations.class.getMethod("level1ClassSimilarityForUser",
                                    String[].class);
System.out.println(":" + parameters[0] + ":");
results = (ResultSet) method.invoke(new TestRecommendations(), parameters)

parameters is a string array, and this is the declaration of my level1ClassSimilarityForUser method

public ResultSet level1ClassSimilarityForUser(String[] userURI) {

I am getting this error:

java.lang.IllegalArgumentException: argument type mismatch

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)

Answer 1

invoke expects an Object[] as second argument (varargs is just a convenience syntax). I think in your case the String[] is not taken as the first vararg argument, but the complete vararg Object[] and thus your single strings are used as arguments which does not match String[].
In your case, explicitly wrapping your parameters in an Object array before giving it to invoke should work.
So do results = (ResultSet) method.invoke(new TestRecommendations(), new Ojbect[] { parameters }) instead