1.Arrays实用功能:equals():比较两个数组是否相等;fill():填充数组;binarySearch():在已经排好序的数组中查找元素;toString():返回数组元素的字符串形式;hashCode():产生数组的散列码;Arrays.asList():接受任意的序列或数组作为其参数,并转变为List容器。
public static void main(String[] args) { int[] arr = {1, 2, 3, 2, 1}; int[] arr2 = {1, 2, 3, 2, 1}; System.out.println(Arrays.equals(arr, arr2)); Arrays.fill(arr2, 2); System.out.println(Arrays.toString(arr2)); System.out.println(Arrays.hashCode(arr)); List list = Arrays.asList(arr); System.out.println(list.size()); }
2.复制数组:System.arrayCopy()用它复制数组比for循环要快。从指定源数组中复制一个数组,复制从指定的位置开始,到目标数组的指定位置结束。
for循环示例:
public static void main(String[] args) { int[] arr1 = {10, 20, 30}; int[] arr2 = new int[arr1.length]; for (int i = 0; i < arr1.length; i++) { arr2[i] = arr1[i]; } for (int i = 0; i < arr2.length; i++) { System.out.println(arr2[i]); } }
System.arrayCopy()示例:
public static void main(String[] args) { int[] arr = {10, 20, 30}; int[] arr2 = new int[2]; System.arraycopy(arr, 0, arr2, 0, arr.length); for (int i = 0; i < arr2.length; i++) { System.out.println(arr2[i]); } }
3.数组的比较:Arrays类提供了重载后的equals方法,用来比较整个数组。
public static void main(String[] args) { int[] arr = {10, 20, 30}; int[] arr2 = {10, 20, 30}; int[] arr3 = {1, 2, 3}; System.out.println(Arrays.equals(arr, arr2)); System.out.println(Arrays.equals(arr, arr3)); }