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

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);
????}
}

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);
????}
}

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);
????????????}
????????}

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]);
????????}

????}
}