API(Arrays)

public class ArraysDemo1 {
    public static void main(String[] args) {
        /*
        public static String toString(数组) //把数组拼接成字符串
        public static int binarySearch(数组,查找的元素) //二分查找法查找
        public static int[] copyOf(原数组,新数组长度) //拷贝数组
        public static int[] copyOfRange(原数组,起始索引,结束索引) //指定范围拷贝数组
        public static void fill(数组,元素) //填充数组
        public static void sort (数组)
        public static void sort (数组,排序规则)
         */

        //1.
        int[] arr = {1,2,3,4,5,6,7,8,9};
        System.out.println(Arrays.toString(arr));
        //2.
        int index = Arrays.binarySearch(arr, 4);
        System.out.println(index);
        //3.
        int []arr2=Arrays.copyOf(arr,10);
        System.out.println(Arrays.toString(arr2));
        //4.
        int []arr3=Arrays.copyOfRange(arr,0,5);//左闭右开
        System.out.println(Arrays.toString(arr3));
        //5.
        Arrays.fill(arr3,10);
        System.out.println(Arrays.toString(arr3));//[10, 10, 10, 10, 10]
        //6.默认升序
        Integer[] arr4={1,4,3,2,5,8,7,6,9};
        Arrays.sort(arr4, new Comparator<Integer>() {//匿名内部类
            @Override
            public int compare(Integer o1, Integer o2) {
                //return o1-o2;//升序
                return o2-o1;//降序
            }
        });
        System.out.println(Arrays.toString(arr4));
    }
}