java练习题之String方法运用

应用知识点：String类

1：(String 类)仔细阅读以下代码段：

String s = "hello";

String t="hello";

char[] c = {'h','e','l','l','o'};

2：下列选项输出结果为false 的语句是()

System.out.println( s.euqals( t ) );

System.out.println( t.equals( c ) );

System.out.println( s==t );

System.out.println( t.equals( new String(c) ) );

System.out.println( t.equals( new String("hello")) );

3：(String 类)关于 java.lang.String 类，以下描述正确的一项是()(看源码)

String 类是 final 类故不可以继承。空间不可变吧

String 类是 final 类故可以继承。

String 类不是 final 类故不可以继承。

String 类不是 final 类故可以继承。

4：(String 类)应用程序的 main 方法中有以下语句，则输出的结果是

A. false B. true C. 1 D. 0

5：(String 类)已知String 对象s=”abcdefg”，则s.substring(2,5)的返回值为（）

A．”bcde” B．”cde” C．”cdef” D．”def”

6：(String 类)已知s 为一个String 对象，s=”abcdefg”，则s.charAt(1)的返回值为（）。

A．a B．b C．f D．g

7：接着实现昨天的题，定义一个person类，要求如下：

① 属性：身份证号,姓名,性别,年龄,户籍,出生日期（String类型,"1998-09-09"）

② 属性私有化，提供get/set,构造方法

③ 介绍格式：（toString）

姓名+户籍+年龄

④ 提供对象比较equals方法，只要身份证号+姓名相同就认为对象相等

⑤ 写一个测试类，定义一个Person数组，创建多个Person对象存储在数组中，

i. 打印输出所有Person对象的信息

ii. 用控制台输入一个Person信息：(注意：跟昨天的输入有区别！！！)

例如："370828199902145066-刘航-男-58-北京-1955/01/01"

判断数组中是否存在和此对象相等的对象(身份证号+姓名相同就认为对象相等)

iii. 判断Person数组中,名字是否有包含"胡"的联系人,有,打印信息.

iv. 任意输入一个姓 ,判断数组中是否存在有此姓的Person对象.

v.输出5月份出生的学生信息

package com.by.homework2;

public class Person{
    private String idCard;
    private String name;
    private String sex;
    private int age;
    private String location;
    private String birthday;

    public Person() {
    }

    public Person(String idCard, String name, String sex, int age, String location, String birthday) {
        this.idCard = idCard;
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.location = location;
        this.birthday = birthday;
    }

    public String getIdCard() {
        return idCard;
    }

    public void setIdCard(String idCard) {
        this.idCard = idCard;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
   /* public String toString(){
        return "姓名:"+name+",户籍："+location+",年龄："+age;
    }*/

    @Override
    public String toString() {
        return "姓名:"+name+",户籍："+location+",年龄："+age;
    }

    public boolean equals(Object o){
        if(this==o){
            return true;
        }
        if (this.getClass()!=o.getClass()||o.getClass()==null){
            return false;
        }
       Person person=(Person) o;
        return this.idCard.equals(person.idCard)&&this.name.equals(person.name);
    }
}



package com.by.homework2;

import java.util.Scanner;

public class PersonTest {
    public static void main(String[] args) {
       Person[]people={new Person("1307262000","张三","男",18,"河北省","2000-01-01"),
                new Person("1307262001","李四","女",19,"河南省","2000-05-01"),
                new Person("1307262002","王五","男",20,"湖北省","2000-03-01"),
                new Person("123456789","胡麻子","男",21,"湖南","2000-11-11")};
        Scanner sc=new Scanner(System.in);
        for (int i = 0; i < people.length; i++) {
            System.out.println(people[i]);
        }
        //查询胡姓人
        boolean boo2=false;
        for (int i = 0; i < people.length; i++) {
            if(people[i].getName().indexOf("胡")==0){
                System.out.println("有胡姓叫："+people[i].getName());
                boo2=true;
            }
        }
        if(!boo2){
            System.out.println("没有胡姓人");
        }
        char[]chars;
        for (int i = 0; i < people.length; i++) {
             chars=people[i].getName().toCharArray();
        }
        /*for (int i = 0; i < chars.length; i++) {
            chars[0]
        }*/
        //查询是否有该姓的名字
        System.out.println("任意输入一个姓，看是否有");
        String name1=sc.next();
        char []chars1=name1.toCharArray();
        String str3= String.valueOf(chars1[0]);
        boolean boo3=false;
        for (int i=0;i< people.length;i++){
            boolean boo4=people[i].getName().contains(str3);
            if (boo4){
                System.out.println("有姓名为：："+people[i]);
                boo3=true;
            }
        }
        if (!boo3){
            System.out.println("无相等的");
        }

        for (int i = 0; i < people.length; i++) {
            if(people[i].getBirthday().indexOf("5")==6){
                System.out.println(people[i]+"，生日为："+people[i].getBirthday());
            }
        }

        for (int i = 0; i < people.length; i++) {
            String str=String.valueOf(people[i].getBirthday().charAt(6));
            if(str.equals("5")){
                System.out.println(people[i]+"，生日为："+people[i].getBirthday());
            }
        }









        System.out.println("请输入身份证号");
        String idCard=sc.next();
        System.out.println("请输入姓名");
        String name=sc.next();
        System.out.println("请输入性别");
        String sex=sc.next();
        System.out.println("请输入年龄");
        int age=sc.nextInt();
        System.out.println("请输入籍贯");
        String location=sc.next();
        System.out.println("请输入出生日期");
        String birthday=sc.next();
        Person person=new Person(idCard,name,sex,age,location,birthday);
        String str=idCard+"-"+name+"-"+sex+"-"+age+"-"+location+"-"+birthday;
        System.out.println(str);
        String []str1=str.split("-");
        boolean boo1=false;
        for (int i = 0; i < people.length; i++) {
            if (str1[0].equals(people[i].getIdCard())&&str1[1].equals(people[i].getName())){
                System.out.println("相等");
                boo1=true;
            }
        }
        if (!boo1){
            System.out.println("不相等");
        }



        //输入一个完整的信息
        System.out.println("请输入信息");

        String infor=sc.next();
        String []strings=infor.split("-");
        Person person1=new Person(strings[0],strings[1],strings[2],Integer.parseInt(strings[3]),strings[4],strings[5]);


        boolean boo=false;
        for (int i = 0; i < people.length; i++) {
            if(person1.equals(people[i])){
                System.out.println("相等的为："+people[i]);
                boo=true;
            }
        }
        if(!boo){
            System.out.println("没有相等的");
        }



    }
}

8：获取“Wangxx@zparkhr.com.cn”中的用户名“Wangxx”

String s3="Wangxx@zparkhr.com.cn";
System.out.println(s3.substring(0,6));

9：验证“Wanxxj@zparkhr.com.cn”是否为一个合法邮箱

合法邮箱要求：

1、有“@”和“.”符号

2、“.”在“@”后面

package com.by.homework2;

public class ContainAndIndexOf {
    public static void main(String[] args) {
        String str="Wanxxj@zparkhr.com.cn";
        if (str.contains("@")&&str.contains(".")){
            if (str.indexOf(".")>str.indexOf("@")){
                System.out.println(str+":是一个合法邮箱");
            }
        }
    }
}

10：控制台输入格式为“张三-18-男-3000.0”的字符串5个，解析为工人对象分别对应为名字，年龄，性别，工资的属性值，并存入工人数组

package com.by.homework2;

import java.util.Scanner;

public class Worker {
    private String name;
    private int age;
    private String sex;
    private double salary;

    public Worker() {
    }

    public Worker(String name, int age, String sex, double salary) {
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "Worker{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                ", salary=" + salary +
                '}';
    }
}

class WorkerTest{
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入员工信息");
        String str=sc.next();
        String []strings=str.split("-");
        String name = null;
        int age=0;
        String sex=null;
        double salary = 0;
        Worker worker1 = null;
        Worker worker2 = null;
        Worker worker3 = null;
        Worker worker4 = null;
        Worker worker5 = null;
        int num=0;
        //zhang-18-nan-1000-li-19-nan-2000-wang-20-nan-3000-zhao-21-nan-4000-qian-22-nan-5000
        for (int i=1;i<=5;i++) {
                name=strings[num];
                age=Integer.parseInt(strings[1+num]);
                sex=strings[2+num];
                salary=Double.parseDouble(strings[3+num]);
                System.out.println(name+age+sex+salary);

               if (i==1){
                   worker1=new Worker(name,age,sex,salary);
               }
               if (i==2){
                   worker2=new Worker(name,age,sex,salary);
               }
               if (i==3){
                   worker3=new Worker(name,age,sex,salary);
               }
               if (i==4){
                   worker4=new Worker(name,age,sex,salary);
               }
               if (i==5){
                   worker5=new Worker(name,age,sex,salary);
               }
//            System.out.println();
            num+=4;
        }
        Worker[] workers={worker1,worker2,worker3,worker4,worker5};
        for (int i = 0; i < workers.length; i++) {
            System.out.println(workers[i].toString());
        }
    }
}

请输入员工信息

zhang-18-nan-1000-li-19-nan-2000-wang-20-nan-3000-zhao-21-nan-4000-qian-22-nan-5000

zhang18nan1000.0

li19nan2000.0

wang20nan3000.0

zhao21nan4000.0

qian22nan5000.0

Worker{name='zhang', age=18, sex='nan', salary=1000.0}

Worker{name='li', age=19, sex='nan', salary=2000.0}

Worker{name='wang', age=20, sex='nan', salary=3000.0}

Worker{name='zhao', age=21, sex='nan', salary=4000.0}

Worker{name='qian', age=22, sex='nan', salary=5000.0}

Process finished with exit code 0

11：银行系统需要登记用户的身份证号，为了防止用户输入身份证号的数位有误，我们应该使用什么方法？

.chatAt（17）！=0 && .charAt(17+) ==0

12：给定一个由数字组成的字符串

如:“376472364760183013010832“；

统计每个数字出现的次数

String s="376472364760183013010832";
byte[] s1=s.getBytes();
int sum=0;
for (int i = 0; i < s1.length; i++) {
    for (int j = 0; j <= s1.length-1; j++) {
    if(s1[i]==s1[i+1]){
    sum++;
    }
    }
    }
    System.out.println(s1[i]+"出现的次数是"+sum);
    }

13：将随机获取的UUID（含义是通用唯一识别码）中的“-”去掉。

提示：java.util.UUID.randomUUID().toString()//可以获取随机UUID

格式：e6c57443-1667-4d75-98f6-a8863d95e58f

package com.by.homework2;
import java.util.UUID;
public class Uuid {
    public static void main(String[] args) {
        String uuid=UUID.randomUUID().toString();
        System.out.println(uuid);
        String []str=uuid.split("-");
        for (int i = 0; i < str.length; i++) {
            System.out.print(str[i]);
        }
    }


}

14:在给定字符串“ABDEFGabdefghijklmnMNKJ1234567"中随机获取4个字符，并使用随机获取的4个字符，使用StringBuilder拼接成字符串（随机获取到4个字符串中不可以出现重复字符,忽略大小写！如果当前随机内容已经出现，则重新随机本次）

提示：创建随机数对象java.util.Random.

java.util.Random r=new java.util.Random();

random.next(100);//可以获取到0-99中任意一个随机数。

获取到的随机数作为字符串的字符下标进行取值。

package com.by.homework2;

import java.util.Random;

public class RandomAppends {
    public static void main(String[] args) {
        String input = "ABDEFGabdefghijklmnMNKJ1234567";
        Random random = new Random();
        StringBuilder sb = new StringBuilder();

        while (sb.length() < 4) {
            int index = random.nextInt(input.length());
            char c = input.charAt(index);
            String str=String.valueOf(c);
            if (!sb.toString().contains(str)) {
                sb.append(c);
            }
        }

        System.out.println(sb.toString());
    }
}

15:将一个字符串进行反转。将字符串中指定部分进行反转。比如"abcdefg"，反转子串"cdef"，转为"abfedcg"

package com.by.homework2;

import java.util.Scanner;

public class Roolback {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入字符串");
        String str=scanner.next();
        System.out.println("反转其中内容");
        String str1=scanner.next();
        int num=str.indexOf(str1);
        char []chars=str.toCharArray();
        char a=0;
        char b=0;
        for (int i = 0; i < chars.length; i++) {
            if (i==num){
                a=chars[i];
                b=chars[i+1];
                chars[i]=chars[i+str1.length()-1];
                chars[i+1]=chars[i+str1.length()-2];
                chars[i+str1.length()-1]=a;
                chars[i+str1.length()-2]=b;


            }
            System.out.print(chars[i]);
        }
       /* String a="abcdefg";
        String b="edcb";
        char[]cs=b.toCharArray();
        String c="";
        for (int i = cs.length-1; i >=0; i--) {
            c+=cs[i];
        }
        System.out.println(a.replace(b,c));*/
    }
}

请输入字符串

abcdefg

反转其中内容

cdef

abfedcg

Process finished with exit code 0

16:使用方法判断字符串“zxcvbnmalskqpwoeiruty156789~!@#$%^&()”和字符串“!^#145agtkdbm”中字符重复的个数

package com.by.homework2;

public class Test15 {
    public static void main(String[] args) {
        String str="zxcvbnmalskqpwoeiruty156789~!@#$%^&*()";
        String str1="!^#*145agtkdbm";
        char []c=str.toCharArray();
        char []c1=str1.toCharArray();
        int num=0;
        for (int i = 0; i < c.length; i++) {
            for (int i1 = 0; i1 < c1.length; i1++) {
                if (String.valueOf(c[i]).equals(String.valueOf(c1[i1]))){
                  num++;
                }
            }
        }
        System.out.println(num);
    }
}

17:以下是一段歌词，请从这段歌词中统计出“朋友”出现的次数及每次的下标。

"这些年一个人，风也过，雨也走，有过泪，有过错, 还记得坚持甚么，真爱过才会懂，会寂寞会回首，终有梦终有你在心中。朋友一生一起走，那些日子不再有，一句话，一辈子，一生情，一杯酒。朋友不曾孤单过，一声朋友你会懂，还有伤，还有痛，还要走，还有我。";

package com.by.homework2;

public class Test16 {
    public static void main(String[] args) {
        String str = "这些年一个人，风也过，雨也走，有过泪，有过错, 还记得坚持甚么，真爱过才会懂，会寂寞会回首，终有梦终有你在心中。朋友一生一起走，那些日子不再有，一句话，一辈子，一生情，一杯酒。朋友不曾孤单过，一声朋友你会懂，还有伤，还有痛，还要走，还有我。";
        int count = 0;
        int index = 0;
        
        while ((index = str.indexOf("朋友", index)) != -1) {
            count++;
            index++; // Move the index to the next character after "朋友"
        }
        System.out.println("朋友出现的次数: " + count);
    }
}

18:编写敏感词过滤程序
说明：在网络程序中，如聊天室、聊天软件等，经常需要对一些用户所提交的聊天内容中的敏感性词语进行过滤。如“性”、“色情”、“爆炸”、“恐怖”、“枪”、“军火”等，这些都不可以在网上进行传播，需要过滤掉或者用其他词语替换掉。

实现：让用户随机输入一段话，如果出现上述的敏感词汇，则用“***”对其进行替换

package com.by.homework2;

import java.util.Scanner;

public class Test17 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入一段话，我来输出");
        String str=sc.next();
        String []strings={"性","色情","爆炸","恐怖","枪","军火"};
        String str2="****";
        for (int i = 0; i < strings.length; i++) {
            if (str.contains(strings[i])){
                str.replace(strings[i],str2);
                System.out.println(str);
            }
        }

19:编写一个程序，设定一个有大小写字母的字符串，先将字符串的大写字符输出，再将字符串中的小写字符输出

package com.by.homework2;

import java.util.Scanner;

public class Test18 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入：");
        String str=sc.next();
        String str1;
        String str2;
        int num=0;
        byte[]bytes=str.getBytes();
        char []chars=new char[bytes.length];
        for (int i = 0; i < bytes.length; i++) {
            if(bytes[i]>=65&&bytes[i]<=90){
                chars[i]= (char) bytes[i];
                num++;
            }
            if(bytes[i]>=97&&bytes[i]<=122){
                chars[i+num]= (char) bytes[i];
            }


        }
        for (int j = 0; j < chars.length; j++) {
            System.out.print(chars[j]);
        }

    }
}