[OCAJP][OCPJP]foreach與陣列物件參考

Given:

public class Test2 {
    public static void main(String[] args) {
        int ar1[] = {2, 4, 6, 8};
        int ar2[] = {1, 3, 5, 7, 9};
        ar2 = ar1;
        for (int e2 : ar2) {
            System.out.print(" " + e2);
        }
    }
}

What is the result?

A.

B.

C.

D.

題解

程式第5行，已經將原先ar2所參考到的陣列物件拋棄了，無需再顧慮它。如果這邊是要將原先ar1陣列物件的元素複製給ar2的話，應該要這樣寫：

public class Test2 {
    public static void main(String[] args) {
        int ar1[] = {2, 4, 6, 8};
        int ar2[] = {1, 3, 5, 7, 9};
        System.arraycopy(ar1, 0, ar2, 0, ar1.length);
        for (int e2 : ar2) {
            System.out.print(" " + e2);
        }
    }
}