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167 - 学生列表
Description
编写学生类，包含学号no、姓名name、成绩score，提供必要的构造函数、toString函数和equals/hashcode函数，其中，toString函数的格式为“no:xxx name:xxx score:xxx”,no参与equals和hashcode的计算
在main函数中构造一个学生列表对象（List），用于存放多个学生对象
从命令行输入多个学生对象，存入列表中
从命令行中读入在列表对象上的操作，具体操作包含：
add 添加一个学生(包含学号和学生姓名）
delete 删除一个学生（包含学号）
set 修改一个学生信息(只修改某学号学生的成绩）
完成操作后按列表顺序输出集合中的学生
Input
学生个数
学生对象数据
操作数
操作内容
Output
列表顺序输出集合中的学生
Sample Input
4
1 wong 90
2 liu 80
3 chen 70
4 fang 60
3
add 5 duan 80
delete 3
set 4 70
Sample Output
no:1 name:wong score:90
no:2 name:liu score:80
no:4 name:fang score:70
no:5 name:duan score:80
MyAnswer
import java.util.*;
/*
* title: 学生列表
* author: V0W
* */
public class Main{
public static void main(String[] args){
ArrayList<Student> ALs = new ArrayList<>();
Scanner scan = new Scanner(System.in);
int stunum = scan.nextInt();
int i,j;
for(i=0; i<stunum; i++){
int no = scan.nextInt();
String name = scan.next();
int score = scan.nextInt();
Student stu = new Student(no,name,score);
ALs.add(stu);
}
int donum = scan.nextInt();
for(i=0; i<donum; i++){
String dothing = scan.next();
if(dothing.equals("add")){
int no = scan.nextInt();
String name = scan.next();
int score = scan.nextInt();
Student stu = new Student(no,name,score);
ALs.add(stu);
}else if(dothing.equals("delete")){
int dno = scan.nextInt();
for(j=0;j<ALs.size(); j++)
if (ALs.get(j).getNo()==dno)
ALs.remove(j);
}else if(dothing.equals("set")){
int setno = scan.nextInt();
int setScore = scan.nextInt();
for(Student stu:ALs)
if(stu.no == setno)
stu.setScore(setScore);
}
}
for(Student s:ALs)
System.out.println(s.toString());
}
}
class Student{
int no;
String name;
int score; //根据题目描述，应该是int，实际情况下double更合适
Student(int no,String name,int score){
this.no = no;
this.name = name;
this.score = score;
}
public int getNo() {
return no;
}
public void setScore(int score) {
this.score = score;
}
@Override
public String toString() {
return "no:"+no+" name:"+name+" score:"+score;
}
@Override
public boolean equals(Object obj) {
if(obj == null)
return false;
else{
boolean res = false;
if(obj instanceof Student){
Student s = (Student)obj;
if(this.no == s.no)
res = true;
}
return res;
}
}
@Override
public int hashCode() {
return no*520+1314; /*这里的hashcode使用下述方法更好*/
/*
* int res = 17;
* res = res*31+no;
* return res;
* */
}
}
168 - 学生Map
Description
修改《学生列表》题目，使用学生Map来存放学生的集合，其中key为学号，value为学生对象
输出时按照学生的学号顺序输出
Input
学生个数
学生对象数据
操作数
操作内容
Output
按照学号顺序输出集合中的学生
Sample Input
4
1 wong 90
2 liu 80
3 chen 70
4 fang 60
3
add 5 duan 80
delete 3
set 4 70
Sample Output
no:1 name:wong score:90
no:2 name:liu score:80
no:4 name:fang score:70
no:5 name:duan score:80
MyAnswer
import java.util.*;
/*
* title: 学生Map
* author V0W
* reference: https://blog.csdn.net/nyist327/article/details/65447506
* https://www.cnblogs.com/Berryxiong/p/6144086.html
* */
public class Main{
public static void main(String[] args){
Map<Integer,Student> hmap = new HashMap<Integer,Student>();
Scanner scan = new Scanner(System.in);
int stunum = scan.nextInt();
int i,j;
for(i=0; i<stunum; i++){
Integer no = scan.nextInt();
String name = scan.next();
int score = scan.nextInt();
Student stu = new Student(no,name,score);
hmap.put(no, stu);
}
int donum = scan.nextInt();
for(i=0; i<donum; i++){
String dothing = scan.next();
if(dothing.equals("add")){
Integer no = scan.nextInt();
String name = scan.next();
int score = scan.nextInt();
Student stu = new Student(no,name,score);
hmap.put(no,stu);
}else if(dothing.equals("delete")){
Integer dno = scan.nextInt();
hmap.remove(dno);
}else if(dothing.equals("set")){
int setno = scan.nextInt();
int setScore = scan.nextInt();
for(Student stu: hmap.values()){
if(stu.getNo()==setno)
stu.setScore(setScore);
}
}
}
for(Student stu: hmap.values()){
System.out.println(stu.toString());
}
}
}
class Student{
int no;
String name;
int score; //根据题目描述，应该是int，实际情况下double更合适
Student(int no,String name,int score){
this.no = no;
this.name = name;
this.score = score;
}
public int getNo() {
return no;
}
public void setScore(int score) {
this.score = score;
}
@Override
public String toString() {
return "no:"+no+" name:"+name+" score:"+score;
}
@Override
public boolean equals(Object obj) {
if(obj == null)
return false;
else{
boolean res = false;
if(obj instanceof Student){
Student s = (Student)obj;
if(this.no == s.no)
res = true;
}
return res;
}
}
@Override
public int hashCode() {
return no*520+1314; /*这里的hashcode使用下述方法更好*/
/*
* int res = 17;
* res = res*31+no;
* return res;
* */
}
}
184 - 4
Description
在上题的基础上构建一个书单类BookList，该类中用一个列表类对象存放书单，提供添加图书（addBook）、查找图
书（searchBook）的函数
main函数从键盘输入多个Book添加到书单中，（添加时，提供书的名称、价格、作者、版本号），而后从键盘读入一
本书，查找该列表对象中是否包含该书，若包含，输出”found: 该书在列表中的序号”，若不包含，
输出“not found”，查找时，提供书的名称、作者、版本号。
Input
添加书的个数
添加的书
查找的书
Output
查找结果
Sample Input
2
ThinkingInJava
86
BruceEckel
4
CoreJava
95
CayS.Horstmann
10
CoreJava
CayS.Horstmann
10
Sample Output
found: 1
Post Append Code
public class Main{
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
BookList bl = new BookList();
int n = s.nextInt();
for (int i=0; i<n;i++) {
bl.addBook(new Book(s.next(),
s.nextInt(),
s.next(),
s.nextInt()));
}
bl.searchBook(new Book(s.next(),
0,
s.next(),s.nextInt()));
}
}
MyAnswer
import java.util.*;
/*
* title: BookList
* author V0W
* reference:
* */
class Book{
String bookname;
int price;
String author;
int version;
Book(String bookname,int price,String author,int version){
this.bookname = bookname;
this.author = author;
this.price = price;
this.version = version;
}
}
class BookList{
List<Book> booklist = new ArrayList<Book>();
void addBook(Book b){
booklist.add(b);
}
void searchBook(Book b){
for(Book i:booklist){
if(i.bookname.equals(b.bookname)&&i.author.equals(b.author)&&i.version==b.version){
System.out.println("found: "+booklist.indexOf(i));
return ;
}
}
System.out.println("not found");
}
}