Given:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | public class Test { public static void main(String[] args) { String[][] chs = new String[2][]; chs[0] = new String[2]; chs[1] = new String[5]; int i = 97; for (int a = 0; a < chs.length; a++) { for (int b = 0; b < chs.length; b++) { chs[a][b] = "" + i; i++; } } for (String[] ca : chs) { for (String c : ca) { System.out.print(c + " "); } System.out.println(); } } } |
What is the result?
A.
97 98
99 100 null null null
B.
91 98
99 100 101 102 103
C. Compilation fails.
D. A NullPointerException is thrown at runtime.
E. An ArraylndexOutOfBoundsException is thrown at runtime.
題解
第10行的for迴圈一開始，a = 0, b = 0，所以chs[0][0] = "97"。
接下來，a = 0, b = 1，所以chs[0][1] = "98"。
然後，a = 1, b = 0，所以chs[1][0] = "99"。
最後，a = 1, b = 1，所以chs[1][1] = "100"，跳出迴圈。
其他沒設定到的陣列元素，初始值為null。
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