insert an element into an array

How can I add a symbol between the elements in array for example add(a, b, c) to add(*a*, *b*, *c*):

public class exercise {
    public static String[] add(String[] strings) {
        String array[] = {""};
        String output = "*" + Arrays.toString(array);
        return array;
    }
}
public static void (String[] args) {
System.out.println(add("a", "b", "c"};
}
}