查错：

11

1.                               public class WhatHappens {

2.                               public static void main(String[] args) {

3.                                   StringBuffer[] stringBuffers = new StringBuffer[10];

4.                                    for (int i = 0; i < stringBuffers.length; i ++) {

5.                                       stringBuffers[i].append("StringBuffer at index " + i);

6.                                   }

7.                               }

8.                           }

Answer: 程序在第定义了数组 StringBuffers[] ，但在使用数组 StringBuffers 对象时没有初始化，要初始化后才能使用。如下第 5 行为对数组对象初始化

1.                           public class ThisHappens {

2.                               public static void main(String[] args) {

3.                                   StringBuffer[] stringBuffers = new StringBuffer[10];

4.                                        for (int i = 0; i < stringBuffers.length; i ++) {

5.                                        stringBuffers[i] = new StringBuffer();

6.                                       stringBuffers[i].append("StringBuffer at index " + i);

7.                                   }

8.                               }

9.                           }