How to work with varargs and reflection

Question

Simple question, how make this code working ?

public class T {      public static void main(String[] args) throws Exception {         new T().m();     }      public // as mentioned by Bozho     void foo(String... s) {         System.err.println(s[0]);     }      void m() throws Exception {         String[] a = new String[]{"hello", "kitty"};         System.err.println(a.getClass());         Method m = getClass().getMethod("foo", a.getClass());         m.invoke(this, (Object[]) a);     } } 

Output:

class [Ljava.lang.String; Exception in thread "main" java.lang.IllegalArgumentException: wrong number of arguments         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)         at java.lang.reflect.Method.invoke(Method.java:597) 

Answer 1

Test.class.getDeclaredMethod("foo", String[].class); 

works. The problem is that getMethod(..) only searches the public methods. From the javadoc:

Returns a Method object that reflects the specified public member method of the class or interface represented by this Class object.

Update: After successfully getting the method, you can invoke it using:

m.invoke(this, new Object[] {new String[] {"a", "s", "d"}}); 

that is - create a new Object array with one element - the String array. With your variable names it would look like:

m.invoke(this, new Object[] {a});