java实现选课系统

2025-05-29 0 24

本文实例为大家分享了java实现选课系统的具体代码,供大家参考,具体内容如下

这个程序主要是练习io(文件读写,序列化),集合框架的使用

学生端可以实现,查找课程,增加选课,删除选课的功能

管理端可以实现对备选课程,学生信息的增删查改

缺点:登陆操作没有实现密码验证和多态。

另外map对象明明put了,可是get的时候竟然会取到null,而且尝试多次,有时候成功,有时候取到null,并不确定。据说这是由多线程引起的map取值为null,因为多线程部分还没开始学习,所以也没做修改。

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//课程信息

package selectcourse;

import java.io.serializable;

public class course implements serializable{

private string id;

private string name;

public course(string id, string name) {

super();

this.id = id;

this.name = name;

}

public course() {

super();

}

public string getid() {

return id;

}

public void setid(string id) {

this.id = id;

}

public string getname() {

return name;

}

public void setname(string name) {

this.name = name;

}

public int hashcode() {

final int prime = 31;

int result = 1;

result = prime * result + ((id == null) ? 0 : id.hashcode());

result = prime * result + ((name == null) ? 0 : name.hashcode());

return result;

}

public boolean equals(object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

if (getclass() != obj.getclass())

return false;

course other = (course) obj;

if (id == null) {

if (other.id != null)

return false;

} else if (!id.equals(other.id))

return false;

if (name == null) {

if (other.name != null)

return false;

} else if (!name.equals(other.name))

return false;

return true;

}

public string tostring() {

return "课程号:" + id + " " + "课程名:" + name;

}

}

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//学生信息

package selectcourse;

import java.io.serializable;

import java.util.hashset;

import java.util.set;

public class student implements serializable,comparable<student>{

private int id;

private string name;

private set<course> courses;

public student(int id, string name) {

super();

this.id = id;

this.name = name;

this.courses = new hashset<course>();

}

public student() {

super();

this.id = 0;

this.name = null;

this.courses = new hashset<course>();

}

public int getid() {

return id;

}

public void setid(int id) {

this.id = id;

}

public string getname() {

return name;

}

public void setname(string name) {

this.name = name;

}

public set<course> getcourses() {

return courses;

}

public void setcourses(set<course> courses) {

this.courses = courses;

}

public int hashcode() {

final int prime = 31;

int result = 1;

result = prime * result + id;

return result;

}

public boolean equals(object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

if (getclass() != obj.getclass())

return false;

student other = (student) obj;

if (id != other.id)

return false;

return true;

}

public string tostring() {

return "学号:"+id+" " +"姓名:"+name;

}

//遍历输出所选课程

public void travese()

{

if(courses.size()>0)

{

for (course course : courses) {

system.out.println(course);

}

}

else

{

system.out.println("还没有选课");

}

}

public int compareto(student s) {

int result=this.id-s.id;

return result;

}

}

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//管理端

package selectcourse;

import java.io.file;

import java.io.fileinputstream;

import java.io.filenotfoundexception;

import java.io.fileoutputstream;

import java.io.ioexception;

import java.io.objectinputstream;

import java.io.objectoutputstream;

import java.util.arraylist;

import java.util.collections;

import java.util.hashmap;

import java.util.list;

import java.util.map;

import java.util.scanner;

public class administratorop {

//管理端,用来管理学生信息和备选课程

list<student> students = new arraylist<student>();

map<integer, student> map1 = new hashmap<integer, student>();

list<course> courses = new arraylist<course>();

map<string, course> map2 = new hashmap<string, course>();

scanner in = new scanner(system.in);

public administratorop() {

}

//~~~~~~~~~~~~~~~~~从文件读入list~~~~~~~~~~~~~~~~~~~~~

public void load1() {

file file = new file("students.txt");

if (!file.exists()) {

try {

file.createnewfile();

} catch (ioexception e) {

e.printstacktrace();

}

}

fileinputstream fis;

try {

fis = new fileinputstream(file);

objectinputstream ois = new objectinputstream(fis);

students = (list<student>) ois.readobject();

ois.close();

fis.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

e.printstacktrace();

} catch (classnotfoundexception e) {

e.printstacktrace();

}

}

public void load2() {

file file = new file("courses.txt");

if (!file.exists()) {

try {

file.createnewfile();

} catch (ioexception e) {

e.printstacktrace();

}

}

fileinputstream fis;

try {

fis = new fileinputstream(file);

objectinputstream ois = new objectinputstream(fis);

courses = (list<course>) ois.readobject();

ois.close();

fis.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

e.printstacktrace();

} catch (classnotfoundexception e) {

e.printstacktrace();

}

}

//将信息写回文件

public void save1() {

file file = new file("students.txt");

fileoutputstream fos;

try {

fos = new fileoutputstream(file);

objectoutputstream oos = new objectoutputstream(fos);

oos.writeobject(students);

oos.close();

fos.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

// todo 自动生成的 catch 块

e.printstacktrace();

}

}

public void save2() {

file file = new file("courses.txt");

fileoutputstream fos;

try {

fos = new fileoutputstream(file);

objectoutputstream oos = new objectoutputstream(fos);

oos.writeobject(courses);

oos.close();

fos.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

// todo 自动生成的 catch 块

e.printstacktrace();

}

}

//~~~~~~~~~~~~~~~~~~~~~~~~~ 根据list来创建map~~~~~~~~~~~~~~~~~~~~~~~

public void createmap1() {

for (int i = 0; i < students.size(); i++) {

map1.put(students.get(i).getid(), students.get(i));

}

}

public void createmap2() {

for (int i = 0; i < courses.size(); i++) {

map2.put(courses.get(i).getid(), courses.get(i));

}

}

// ~~~~~~~~~~~~~~~~~~~~~~ 增删查改~~~~~~~~~~~~~~~~~~~~~~~

// 增加学生基本信息

public void add() {

system.out.println("输入学生信息,输入0结束");

while (true) {

int id = in.nextint();

if(id!=0) {

string name = in.next();

student s = new student(id, name);

students.add(s);

collections.sort(students);

map1.put(id, s);

system.out.println("添加成功");

}

if (id == 0) {

break;

}

}

}

// 删除学生信息

public void del() {

while(true) {

int id = in.nextint();

student s = map1.get(id);

students.remove(s);

map1.remove(id);

system.out.println("移除成功");

if (id == 0) {

break;

}

}

}

// 增加课程基本信息

public void add2() {

system.out.println("输入课程信息,输入end结束");

while (true) {

string id = in.nextline();

if(!id.equals("end"))

{

string name = in.nextline();

course cr = new course(id, name);

courses.add(cr);

map2.put(id, cr);

system.out.println("添加成功");

}

else{

//system.out.println("添加结束");

break;

}

}

}

// 删除课程信息

public void del2() {

while(true) {

string id = in.next();

if(!id.equals("end")) {

course cr = map2.get(id);

courses.remove(cr);

map2.remove(id);

system.out.println("移除成功");

}

else

{

break;

}

}

}

// 根据学号查找学生

public void query1() {

system.out.println("请输入要查询的学生学号:");

if (in.hasnext()) {

int id = in.nextint();

system.out.println(map1.get(id));

map1.get(id).travese();

}

}

// 根据课程号查找课程

public void query2() {

system.out.println("请输入要查询的课程号:");

if (in.hasnext()) {

string id = in.nextline();

system.out.println(map2.get(id));

}

}

// 修改学生基本信息

public void modify1() {

system.out.println("请输入要修改的学生的学号:");

int id = in.nextint();

student s = map1.get(id);

system.out.println("输入修改后的学生信息:");

int no = in.nextint();

string name = in.next();

int i = students.indexof(s);

students.set(i, new student(no, name));

collections.sort(students);

map1.remove(id);

map1.put(no, new student(no, name));

system.out.println("修改成功");

}

// 修改课程信息

public void modify2() {

system.out.println("请输入要修改的课程的课程号:");

string id = in.nextline();

course cr = map2.get(id);

system.out.println("输入修改后的课程信息:");

string no = in.nextline();

string name = in.nextline();

int i = courses.indexof(cr);

courses.set(i, new course(no, name));

map2.remove(id);

map2.put(no, new course(no, name));

system.out.println("修改成功");

}

// ~~~~~~~~~~~~~~~~~~~~~~ 遍历list~~~~~~~~~~~~~~~~~~~~~~~

void display1() {

system.out.println("所有的学生信息:");

for (student s : students) {

system.out.println(s.tostring());

s.travese();

}

}

void display2() {

system.out.println("所有的备选课程信息:");

for (course course : courses) {

system.out.println(course.tostring());

}

}

public void close()

{

in.close();

}

}

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//学生操作端

package selectcourse;

import java.io.file;

import java.io.fileinputstream;

import java.io.filenotfoundexception;

import java.io.fileoutputstream;

import java.io.ioexception;

import java.io.objectinputstream;

import java.io.objectoutputstream;

import java.util.arraylist;

import java.util.hashmap;

import java.util.list;

import java.util.map;

import java.util.scanner;

public class studentop {

scanner in = new scanner(system.in);

student st;

list<student> students = new arraylist<student>();

list<course> courses = new arraylist<course>();

map<string, course> map = new hashmap<string, course>();

public studentop(int no) {

load3(no);

load4();

}

// ~~~~~~~~~~~~~~~~~从文件读入信息~~~~~~~~~~~~~~~~~~~~~

public void load3(int n) {

file file = new file("students.txt");

fileinputstream fis;

try {

fis = new fileinputstream(file);

objectinputstream ois = new objectinputstream(fis);

students = (list<student>) ois.readobject();

ois.close();

fis.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

e.printstacktrace();

} catch (classnotfoundexception e) {

e.printstacktrace();

}

for (int i = 0; i < students.size(); i++) {

if (n == students.get(i).getid()) {

st = students.get(i);

break;

}

}

}

public void load4() {

file file = new file("courses.txt");

if (!file.exists()) {

try {

file.createnewfile();

} catch (ioexception e) {

e.printstacktrace();

}

}

fileinputstream fis;

try {

fis = new fileinputstream(file);

objectinputstream ois = new objectinputstream(fis);

courses = (list<course>) ois.readobject();

ois.close();

fis.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

e.printstacktrace();

} catch (classnotfoundexception e) {

e.printstacktrace();

}

}

// 将信息写回文件

public void save3() {

file file = new file("students.txt");

fileoutputstream fos;

try {

fos = new fileoutputstream(file);

objectoutputstream oos = new objectoutputstream(fos);

oos.writeobject(students);

oos.close();

fos.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

// todo 自动生成的 catch 块

e.printstacktrace();

}

}

public void save4() {

file file = new file("courses.txt");

fileoutputstream fos;

try {

fos = new fileoutputstream(file);

objectoutputstream oos = new objectoutputstream(fos);

oos.writeobject(courses);

oos.close();

fos.close();

} catch (filenotfoundexception e) {

e.printstacktrace();

} catch (ioexception e) {

// todo 自动生成的 catch 块

e.printstacktrace();

}

}

//~~~~~~~~~~~~~~~~~~~~~~~~~ 根据list来创建map~~~~~~~~~~~~~~~~~~~~~~~

public void createmap() {

for (int i = 0; i < courses.size(); i++) {

map.put(courses.get(i).getid(), courses.get(i));

}

//遍历map

/*set<string> set = map.keyset();

iterator<string> iterator = set.iterator();

while (iterator.hasnext()) {

string key = iterator.next();

system.out.println(key + " " + map.get(key));

} */

}

//遍历显示备选课程

public void displayallcourse() {

system.out.println("所有的备选课程信息:");

for (course course : courses) {

system.out.println(course.tostring());

}

}

//根据课程号查询备选课程

public void querycourse() {

system.out.println("请输入要查询的课程号:");

string str = in.next();

system.out.println(str);

system.out.println((map.containskey(str) ? "yes" : "no"));

system.out.println(map.get(str));

}

//显示所选课程

public void display() {

system.out.println("所选课程:");

st.travese();

}

//增加所选课程

public void addselect() {

system.out.println("输入所选课程的课程号,输入end结束");

while (true) {

string id = in.nextline();

if (!id.equals("end")) {

course cr = map.get(id);

st.getcourses().add(cr);

system.out.println("选课成功");

} else {

// system.out.println("添加结束");

break;

}

}

}

//减少所选课程

public void deleteselect() {

system.out.println("要删除课程的课程号,输入end结束");

while (true) {

string id = in.nextline();

if (!id.equals("end")) {

course cr = map.get(id);

st.getcourses().remove(cr);

system.out.println("删除成功");

} else {

// system.out.println("添加结束");

break;

}

}

}

public void close() {

in.close();

}

}

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//测试类

package selectcourse;

import java.util.scanner;

public class test {

public static void main(string[] args) {

//~~~~~~~~~~~~~测试管理端~~~~~~~~~~~~~~~~~~~~~~~~~~

/*添加学生

administratorop a1=new administratorop();

a1.add();

//a1.display1();

// a1.close();

a1.save1();*/

/*添加课程

administratorop a2=new administratorop();

a2.add2();

//a2.display2();

a2.close();

a2.save2();*/

/* // 测试删除,查找,修改

administratorop a3=new administratorop();

a3.load1();

a3.createmap1();

a3.load2();

a3.createmap2();

// a3.display1();

// a3.display2();

// a3.del();

// a3.display1();

// a3.del2();

// a3.display2();

// a3.query1();

// a3.query2();

// a3.modify1();

// a3.display1();

// a3.modify2();

// a3.display2();

a3.close();

// a3.save1();

// a3.save2();*/

//~~~~~~~~~~~~~~~~测试学生端~~~~~~~~~~~~~~~~~~~~~~~~~

/*scanner in=new scanner(system.in);

system.out.println("请输入学号:");

int id=in.nextint();

studentop sto=new studentop(id);

sto.createmap();

//sto.displayallcourse();

//sto.querycourse();

// sto.addselect();

// sto.deleteselect();

sto.display();

sto.close();

in.close();

// sto.save3();

// sto.save4();

*/ }

}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持快网idc。

原文链接:https://blog.csdn.net/wrxingkong/article/details/81486148

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