Arrays 数组工具类常用方法

java.util.Arrays类即为操作数组的工具类，包含了用来操作数组（比如排序和搜索）的各种方法

equals：比较两个数组是否相等

int[] arr1 = new int[]{1,2,3};
int[] arr2 = new int[]{1,2,3};
boolean equals = Arrays.equals(arr1, arr2);
System.out.println(equals); // true

toString：输出数组信息

int[] arr1 = new int[]{1,2,3};
System.out.println(Arrays.toString(arr1)); // [1,2,3]

fill：数组填充

int[] arr1 = new int[]{1,2,3};
// 全部填充
Arrays.fill(arr1, 4);
System.out.println(Arrays.toString(arr1)); // [4,4,4]
//指定填充
int[] arr1 = new int[]{1,2,3};
Arrays.fill(arr1, 1,2,4);
System.out.println(Arrays.toString(arr1)); // [1,4,3]

sort：数组排序

int[] arr1 = new int[]{1,7,3,5};
Arrays.sort(arr1);
System.out.println(Arrays.toString(arr1)); // [1,3,5,7]

binarySearch：二分查找（数组有序）

int[] arr1 = new int[]{1,7,3,5};
Arrays.sort(arr1);
int index = Arrays.binarySearch(arr1,3);
System.out.println(index); // 1
index = Arrays.binarySearch(arr1,9);
System.out.println(index); // -5（负数表示不存在）

copyOf/copyOfRange：数组复制

int[] arr1 = new int[]{1,7,3,5};
int[] arr2 = Arrays.copyOf(arr1, 2); // 复制的长度
System.out.println(Arrays.toString(arr2)); // [1,7]int[] arr1 = new int[]{1,7,3,5};
int[] arr2 = Arrays.copyOfRange(arr1, 1,3);
System.out.println(Arrays.toString(arr2)); // [7,3]