韩顺平Java30——常用类Homework

1.

 

 

public static void main(String[] args) {
        String s="abcdef";
        System.out.println("交换前："+s);
        try {
            s=reverse(s,1,4);
        } catch (Exception e) {
            System.out.println(e.getMessage());
            return;
        }
        System.out.println("交换后："+s);

    }
    public static String reverse(String str,int start,int end){
        char [] chars = str.toCharArray();
        char temp = ' ';
        if (!(str!=null && start < end && start>=0 && end<str.length())){
            throw new RuntimeException("参数错误！");
        }
        for (int i =start,j = end;i < j;i++,j--){
            temp=chars[i];
            chars[i]=chars[j];
            chars[j]=temp;
        }

        return new String(chars);
    }

 

 

 

2.

　　

package homework;

import java.util.Scanner;

/**
 * @author 紫英
 * @version 1.0
 * @discription
 */
public class Homework05 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入id：");
        String id = scanner.next();
        System.out.println("请输入password：");
        String password = scanner.next();
        System.out.println("请输入email：");
        String email = scanner.next();
        try {
            userRig(id, password, email);
            System.out.println("success!");

        } catch (Exception e) {
            System.out.println(e.getMessage());

        }

    }

    public static void userRig(String id, String password, String email) {
        if (!(email != null && password != null && email!=null)){
            throw new RuntimeException("参数不能为空");
        }

        if (!(id.length() >= 2 && id.length() <= 4)) {
            throw new RuntimeException("用户名长度需为2-4个字符！");
        }
        if (!((password.length() == 6) && isNum(password))) {
            throw new RuntimeException("密码格式有误");
        }
        if (isEmail(email) == false) {
            throw new RuntimeException("email格式有误");
        }


    }


    public static boolean isNum(String password) {
//        检测是否为数字
        char[] p = password.toCharArray();
        for (int i = 0; i < p.length; i++) {
//            这个我没想到
            if (p[i] < '0' || p[i] > '9') {
                return false;
            }

        }
        return true;
    }

    public static boolean isEmail(String email) {
//        检测@是否在.前面
        StringBuffer sb = new StringBuffer(email);
        if (!(sb.indexOf("@") - sb.indexOf(".") < 0)) {
            return false;
        }
        return true;
    }
}

 3.

 

package homework;

import java.util.Locale;
import java.util.Scanner;

/**
 * @author 紫英
 * @version 1.0
 * @discription 名字格式化
 */
public class Homework07 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入名字：");
        String name = scanner.nextLine();
        nameformat(name);


    }

    public static void nameformat(String name) {
        if (name==null){
            System.out.println("名字为空！");
            return;
        }
        String[] sname = name.split(" ");
        if (sname.length!=3){
            System.out.println("名字格式不正确！（Xxx xxx Xxx）");
            return;
        }
        System.out.println(sname[2] + "," + sname[0] + "," + " ." + sname[1].toUpperCase(Locale.ROOT).charAt(0));
    }
}

老师改进：

        System.out.println(String.format("%s,%s .%c",sname[2] ,sname[0],sname[1].toUpperCase(Locale.ROOT).charAt(0)));

 

4.

 

 

 

 

package homework;

import java.util.Scanner;

/**
 * @author 紫英
 * @version 1.0
 * @discription
 */
public class Homework08 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入字符：");
        String s=scanner.next();
        judge(s);

    }
    public static void judge(String s){
        int up=0;
        int down=0;
        int num=0;
        int other=0;
        char[] c=s.toCharArray();
        for (char c1 : c) {
            if (c1>='a'&&c1<='z'){
                down++;
            }
            if (c1>='A'&&c1<='Z'){
                up++;
            }
            if (c1>='0'&&c1<='9'){
                num++;
            }else {
                other++;
            }
        }
        System.out.println("大写字母"+up+"个"+"小写字母"+down+"个"+"数字"+num+"个"+"其他字符"+other+"个");

    }
}

 

5.

 

 FFTFFT