What will the following code print out to console?


public class Exam  {
    public static void main(String[] arg) {
        Object obj = null;
        String str = new String("str");
        str = (String) obj;
        obj = new String("obj");
        System.out.print(obj + ", " + str);  
    }
}

null, null
obj, null
obj, str
obj, obj
None of the above

Explanation

The next commands will be executed in order:
1. obj is initialized with null
2. str is initialized with new String object with value "str"
3. null is assigned to str
4. "obj" string is assigned to obj