Merge sort integer array (non-interface)

public class 归并排序1 {
    public static void sort(int[] arr) {
        int left = 0;
        int right = arr.length - 1;
        devide(arr, left, right);
    }

    private static void devide(int[] arr, int left, int right) {
        int mid = (left + right) / 2;
        if (left < right) {
            devide(arr, left, mid);
            devide(arr, mid + 1, right);
            merge(arr, left, mid, mid + 1, right);
        }
    }

    private static void merge(int[] arr, int left, int mid, int i, int right) {
        int[] temp = new int[arr.length];
        int m = left;//m为temp数组的起始索引
        int ls = left, le = mid;//ls为左边数组的起始索引
        int rs = i, re = right;//rs为右边数组的起始索引
        //至少排完一边
        while (ls <= le && rs <= re) {
            if (arr[ls] < arr[rs]) {
                temp[m++] = arr[ls];
                ls++;
            } else {
                temp[m++] = arr[rs];
                rs++;
            }
        }
        if (ls <= le) {
            for (int j = ls; j <= le; j++) {
                temp[m++] = arr[j];
            }
        }
        if (rs <= re) {
            for (int j = rs; j <= re; j++) {
                temp[m++] = arr[j];
            }
        }
        for (int j = left; j <= right; j++) {
            arr[j] = temp[j];
        }
    }
}

test:

public class Test1 {
    public static void main(String[] args) {
        int[] a = {23, 12, 45, 56, 49};
        归并排序1.sort(a);
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
    }
}

Output: