[OCAJP]建立物件2

Given:

public class MarkList {

    int num;

    public static void graceMarks(MarkList obj4) {
        obj4.num += 10;
    }

    public static void main(String[] args) {
        MarkList obj1 = new MarkList();
        MarkList obj2 = obj1;
        MarkList obj3 = null;
        obj2.num = 60;
        graceMarks(obj2);
    }
}

How many objects are created in the memory runtime?

A. 1
B. 2
C. 3
D. 4

題解

僅在第10行有用new運算子實體化出一個MarkList物件。