40、作业

我不是女神ヾ 2024-03-31 10:00 43阅读 0赞

1、![b72f11ec5e804f949c879be79c2591e5.png][]

//我的代码：

package Homework__;
    
    public class Homework01 {
        public static void main(String[] args) {
            String string="abcdef";
            System.out.println(reverse(string,1,5));
        }
        public static String reverse(String str,int start,int end){
            char[] c=str.toCharArray();
            char temp=' ';
            for(int i=start,j=end;j>i;i++,j--){
                temp=c[i];
                c[i]=c[j];
                c[j]=temp;
            }
            return str=String.valueOf(c);
            //return new String(c);这是字符数组转字符串的第二种方式
    
        }
    }
    //输出：afedcb

//老师的代码：

package Homework__;
    
    public class Homework01 {
        public static void main(String[] args) {
            String string="abcdef";
            System.out.println("====交换前====");
            System.out.println(string);
            try {
                string=reverse(string,-1,5);
            } catch (Exception e) {
                System.out.println(e.getMessage());
                return;
            }
            System.out.println("====交换后====");
            System.out.println(string);
        }
        public static String reverse(String str,int start,int end){
            //对输入的参数做一个验证
            //编程思想：
            //1、写出正确的情况
            //2、然后取反即可
            if(!(str != null && start >= 0 && end>start && end<str.length() && end<str.length())){
                throw new RuntimeException("参数不正确!");
            }
            char[] c=str.toCharArray();
            char temp=' ';
            for(int i=start,j=end;j>i;i++,j--){
                temp=c[i];
                c[i]=c[j];
                c[j]=temp;
            }
            return new String(c);
        }
    }
    //输出：
    //====交换前====
    //abcdef
    //参数不正确!

2、![cae62f55ef3c4592a6e16ea164f8f482.png][]

//我的代码：

package Homework__;
    
    import java.util.Scanner;
    
    public class Homework02 {
        public static void main(String[] args) {
            boolean result= false;
            try {
                result = register("jack","123456","@.com");
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
            if(result){
                System.out.println("注册成功！");
            }
        }
        public static boolean register(String name,String pi,String email){
            if(!(name.length()==2||name.length()==3||name.length()==4)){
                throw new RuntimeException("用户名输入错误！");
            }
            boolean result=true;
            char[] c=pi.toCharArray();
            for(int i=0;i<6;i++){
                if(c[i]>'0'&&c[i]<'9'){
                }else{
                    result=false;
                    break;
                }
            }
            if(!(pi.length()==6&&result==true)){
                throw new RuntimeException("密码输入错误！");
            }
            if(!(email.indexOf('@')!=-1&&email.indexOf('.')!=-1&&email.indexOf('@')<email.indexOf('.'))){
                throw new RuntimeException("邮箱输入错误！");
            }
            return true;
        }
    }

//老师的代码：

package Homework__;
    
    import java.util.Scanner;
    
    public class Homework02 {
        public static void main(String[] args) {
            String name="jack";
            String pwd="123456";
            String email="jack@sohu.com";
            try {
                userRegister(name,pwd,email);
                System.out.println("恭喜你，注册成功！");
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
    
        }
        public static void userRegister(String name,String pwd,String email){
            if(!(name!=null&&pwd!=null&email!=null)){
                throw new RuntimeException("参数不能为空");
            }
            //第一关
            int userLength=name.length();
            if(!(userLength>=2&&userLength<=4)){
                throw new RuntimeException("用户名输入错误，长度应该为2或3或4！");
            }
    
            //第二关
            //单独地写一个方法，判断密码是否全部是数字字符
            if(!(pwd.length()==6 && isDigital(pwd))){
                throw new RuntimeException("密码输入错误，长度应该是6，要求全部是数字！");
            }
    
            //第三关
            int i=email.indexOf('@');
            int j=email.indexOf('.');
            if(!(i>0&&j>i)){
                throw new RuntimeException("邮箱输入错误，应该同时包含@和.且@位于.的前面！");
            }
        }
        public static boolean isDigital(String str){
            char[] chars=str.toCharArray();
            for(int i=0;i<chars.length;i++){
                if(chars[i]<'0'&&chars[i]>'9'){//错误的情形
                    return false;
                }
            }
            return true;//没有执行if语句的方法体，即为正确的情形
        }
    }

3、![7997bc61335a4a808e4d236e6d88bb5e.png][]

//我的代码：

//考查String的方法
    package Homework__;
    
    public class Homework03 {
        public static void main(String[] args) {
            String name="Willian Jefferson Clinton";
            printf(name);
        }
        public static void printf(String abbrevName){
            String[] split=abbrevName.split(" ");
            char c=' ';
            c=split[1].charAt(0);
            abbrevName="";
            abbrevName=abbrevName.concat(split[2]).concat(".").concat(split[0]).concat(".").concat(String.valueOf(c));
            System.out.println(abbrevName);
        }
    }
    //输出：Clinton.Willian.J

//老师的代码：

package Homework__;
    
    public class Homework03 {
        public static void main(String[] args) {
            String name="Han shun Ping";
            printName(name);
        }
        public static void printName(String str){
            if(str==null){
                System.out.println("str不能为空");
                return;
            }
            String[] names=str.split(" ");
            if(names.length!=3){
                System.out.println("输入的字符串格式不对");
                return;
            }
            String format=String.format("%s.%s.%c",names[2],names[0],names[1].toUpperCase().charAt(0));
            System.out.println(format);
        }
    }
    //Ping.Han.S

4、![7d401beed4e64f759c2ba7b749a62074.png][]

//我的代码：

package Homework__;
    
    public class Homework04 {
        public static void main(String[] args) {
            String string="abcABCD12345";
            System.out.println(judge(string));
        }
        public static String judge(String str){
            char[] chars=str.toCharArray();
            int upper=0,lower=0,digital=0;
            for(int i=0;i<chars.length;i++){
                if(chars[i]>='A'&&chars[i]<='Z'){
                    upper++;
                }else if(chars[i]>='a'&&chars[i]<='z'){
                    lower++;
                }else if(chars[i]>='0'&&chars[i]<='9'){
                    digital++;
                }
            }
            return "大写字母有："+upper+"个，小写字母有："+lower+"个，数字有："+digital+"个";
        }
    }
    //大写字母有：4个，小写字母有：3个，数字有：5个

//老师的代码：

package Homework__;
    
    public class Homework04 {
        public static void main(String[] args) {
            String string="abcABCD12345";
            countStr(string);
        }
        public static void countStr(String str){
            if(str==null){
                System.out.println("str不能为空");
                return;
            }
            int strlen=str.length();
            int numCount=0;
            int lowerCount=0;
            int upperCount=0;
            int otherCount=0;
            for(int i=0;i<strlen;i++){
                if(str.charAt(i)>='A'&&str.charAt(i)<='Z'){
                    upperCount++;
                }else if(str.charAt(i)>='a'&&str.charAt(i)<='z'){
                    lowerCount++;
                }else if(str.charAt(i)>='0'&&str.charAt(i)<='9'){
                    numCount++;
                }else{
                    otherCount++;
                }
            }
            System.out.println("大写字母有："+upperCount);
            System.out.println("小写字母有："+lowerCount);
            System.out.println("数字有："+numCount);
            System.out.println("其他的有："+otherCount);
        }
    }
    //大写字母有：4
    //小写字母有：3
    //数字有：5
    //其他的有：0

5、

package Homework__;
    
    public class Homework05 {
        public static void main(String[] args) {
            String s1="hspedu";
            String s4=new String("hspedu");
            String s5="hspedu";
            System.out.println(s1==s4);//F
            System.out.println(s4==s5);//F
    
            Animal a=new Animal(s1);
            Animal b=new Animal(s1);
            System.out.println(a==b);//F
            System.out.println(a.equals(b));//F //Animal没有重写父类的equals方法，所以此语句本质上还是比较对象，看下面两张调试图
            System.out.println(a.name==b.name);//T
    
            String t1="hello"+s1;
            String t2="hellohspedu";
            System.out.println(t1.intern()==t2);//T
        }
    }
    class Animal{
        String name;
        public Animal(String name){
            this.name=name;
        }
    }

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[b72f11ec5e804f949c879be79c2591e5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/63af466bb1344ebc806c20d1c0db9778.png
[cae62f55ef3c4592a6e16ea164f8f482.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/12ac9dd295b0439099f5a7d7ef7fd6a6.png
[7997bc61335a4a808e4d236e6d88bb5e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/7792247fca954a5ca1ec49be576aacb9.png
[7d401beed4e64f759c2ba7b749a62074.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/c113ddeec3234c4db2ac18928272a87c.png
[99d795bfbfa24b5cbc177658dbe38b25.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/99ab2c05369546808931dd50175bf721.png
[13ed0b0b0bc94214a0beaf254dac42a5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/18bad54b0b32414fb16f70404544b056.png
[e9c3645b98d64d28a204399ece2fc61a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/5472c19056e8402795205424c8c62fc5.png