Javaバブルソート、選択ソート、二分検索

public class Main {
    public static void main(String[] args) {
        int[] arr = { 123, 213, 232, 234, 253, 312, 423, 521 };
        // maopao(arr); //     
        // xuanze(arr); //     
        System.out.println(erfen(arr, 423)); //     ，    ，      
        print(arr);
    }

    private static int erfen(int[] arr, int want) {
        int min = 0;
        int max = arr.length - 1;
        int mid = (min + max) / 2;
        while (arr[mid] != want) {
            if (arr[mid] < want) {
                min = mid + 1;
            } else if (arr[mid] > want) {
                max = mid - 1;
            }
            if (min > max) {
                return -1;
            }
            mid = (min + max) / 2;
        }
        return mid;
    }

    private static void xuanze(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++) {
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[i] > arr[j]) {
                    int temp = arr[j];
                    arr[j] = arr[i];
                    arr[i] = temp;
                }
            }
        }
    }

    private static void maopao(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr.length - 1 - i; j++) {
                if (arr[j] > arr[j + 1]) {
                    int temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
        }
    }

    private static void print(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + ", ");
        }
    }
}