Working with Java arrays

Question

/**
 * Testing Arrays
 * @author N002213F
 * @version 1.0
 */
public class JavaArrays {

    public void processNames(String[] arg) {
        //-- patented method, stop, do not read ;)
    }

    public void test() {

        // works fine
        String[] names1 = new String[] { "Jane", "John" };
        processNames(names1);

        // works fine, nothing here
        String[] names2 = { "Jane", "John" };
        processNames(names2);

        // works again, please procced
        processNames(new String[] { "Jane", "John" });

        // fails, why, are there any reasons?
        processNames({ "Jane", "John" });

        // fails, but i thought Java 5 [vargs][1] handles this
        processNames("Jane", "John");
    }
}

Answer 1

On your last line : processNames(String ...args); would have to be written like this for varargs to work.

Answer 2

processNames({ "Jane", "John" });

This fails, why, are there any reasons?

You didn't specify a type. Java doesn't do type inference here; it expects you to specify that this is a string array. The answers to this question may help for this, too

processNames("Jane", "John"); 

This fails too, but I thought Java 5 varargs handles this

If you want varargs, then you should write your method as such:

public void processNames(String... arg)

Note the ... instead of []. Just accepting an array doesn't entitle you to use varargs on that method.

Answer 3

The third call is incorrect because you cannot create an array like that, you do it like you do in the second call. If you want the final call to succeed you must declare processNames as being a receiver of varargs (see here)