有关java的几个问题

这三个题，难倒我了，我初学java不是很熟练。这三个题，难倒我了，我初学java不是很熟练。

将字符串转为char数组，排序后，转为字符串。

http://t.csdn.cn/5dEol

第三题核心代码：
private String reverseText(String text) {
return new StringBuffer(text).reverse().toString();
}
System.out.println(reverseText(输入的字符串));

如有帮助，请采纳
有问题==》V：uoshuan-j

第三题

public static void main(String[] args) {
        System.out.print("反转前===>");
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();


        StringBuffer stringBuffer = new StringBuffer(str);
        StringBuffer reverse = stringBuffer.reverse();

        System.out.println("反转后===>"+reverse);
    }

第二题

public static void main(String[] args) {
        int i = 3;
        do {
            System.out.println("请输入用户名：");
            Scanner scanner = new Scanner(System.in);
            String username = scanner.nextLine();
            System.out.println("请输入密码：");
            String password = scanner.nextLine();

            if ("admin".equals(username) && "123".equals(password)){
                System.out.println("登录成功");
                break;
            }else {
                System.out.println("您还有"+--i+"次机会");
                continue;
            }

        }while (i>=1);
    }

第一题

 public static void main(String[] args) {
        System.out.print("排序前：");
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        char[] chs = s.toCharArray();
        bubbleSort(chs);
        String result = String.valueOf(chs);
        System.out.println("排序后：" + result);
    }
    public static void bubbleSort(char[] chs) {
        for (int x = 0; x < chs.length - 1; x++) {
            for (int y = 0; y < chs.length - 1 - x; y++) {
                if (chs[y] > chs[y + 1]) {
                    char temp = chs[y];
                    chs[y] = chs[y + 1];
                    chs[y + 1] = temp;
                }
            }
        }
    }

题目一希望对你有所帮助

import java.util.Arrays;

public class characterSorting {
    public static void main(String[] args) {
        String str = "wangshiqiwangyinuo";
        System.out.println("之前："+str);
        char[] chars = str.toCharArray();
        Arrays.sort(chars);
        //正序遍历输出
        System.out.println("之后：");
        for (int i = 0; i < chars.length; i++) {
            System.out.print(chars[i]);
        }
    }
}

public static void main(String[] args) {
        System.out.print("排序前：");
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        StringBuffer stringBuffer  = new StringBuffer(s);
        System.out.println("排序后:"+stringBuffer.reverse());
    }

public static void main(String[] args) {
    System.out.print("排序前：");
    Scanner scanner = new Scanner(System.in);
    String s = scanner.nextLine();
    char[] chs = s.toCharArray();
    bubbleSort(chs);
    String result = String.valueOf(chs);
    System.out.println("排序后：" + result);
}
    public static void bubbleSort(char[] chs) {
        for (int x = 0; x < chs.length - 1; x++) {
            for (int y = 0; y < chs.length - 1 - x; y++) {
                if (chs[y] > chs[y + 1]) {
                    char temp = chs[y];
                    chs[y] = chs[y + 1];
                    chs[y + 1] = temp;
                }
            }
        }

public static void main(String[] args) {
        int i = 3;
        do {
            System.out.println("请输入用户名：");
            Scanner scanner = new Scanner(System.in);
            String username = scanner.nextLine();
            System.out.println("请输入密码：");
            String password = scanner.nextLine();

            if ("admin".equals(username) && "123".equals(password)){
                System.out.println("登录成功");
                break;
            }else {
                i--;
                System.out.println("您还有"+i+"次机会");
                continue;
            }

        }while (i>=1);
    }