41 Java语言基础数组操作的两个常见小问题越界和空指针
1 class Demo3_Array{ 2 public static void main(String[] args) { 3 int[] arr = {1,2,3}; 4 System.out.println(arr[4]); //Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4 5 6 } 7 }
当访问数组中不存在的索引时,会引发越界异常
1 class Demo3_Array{ 2 public static void main(String[] args) { 3 int[] arr = {1,2,3}; 4 System.out.println(arr[4]); //Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4 5 6 7 arr = null; 8 System.out.println(arr[0]);//Exception in thread "main" java.lang.NullPointerException 9 } 10 }
当引用赋值为null再去调用数组中的元素,就会引发空指针异常.