java Implement Course Selection System
- 2021-06-29 11:15:59
- OfStack
The specific code of java course selection system is shared for your reference, which is as follows:
This program mainly practices IO (file read-write, serialization), the use of the collection framework
The student side can realize the functions of finding courses, adding and deleting courses selection
The management side can implement the addition, deletion and alteration of alternative courses and student information
Disadvantages: The login operation does not implement password validation and polymorphism.
In addition, the map object clearly indicates put, but when get, it unexpectedly gets null, and tries several times, sometimes succeeds, sometimes gets null, which is uncertain.It is said that this is caused by multi-threading map value null, because the multi-threaded part has not yet started learning, so no modifications have been made.
// Course information
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 " Course number: " + id + " " + " Course title: " + name;
}
}
// Student Information
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 " School Number: "+id+" " +" Full name: "+name;
}
// Traverse Output Selected Course
public void travese()
{
if(courses.size()>0)
{
for (Course course : courses) {
System.out.println(course);
}
}
else
{
System.out.println(" Lesson not yet selected ");
}
}
public int compareTo(Student s) {
int result=this.id-s.id;
return result;
}
}
//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();
}
}
// Student Operator
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();
}
// ~~~~~~~~~~~~~~~~~ Read information from file ~~~~~~~~~~~~~~~~~~~~~
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();
}
}
// Write information back to the file
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 Auto-generated catch block
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 Auto-generated catch block
e.printStackTrace();
}
}
//~~~~~~~~~~~~~~~~~~~~~~~~~ according to List To create Map~~~~~~~~~~~~~~~~~~~~~~~
public void createMap() {
for (int i = 0; i < courses.size(); i++) {
map.put(courses.get(i).getId(), courses.get(i));
}
// ergodic 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));
} */
}
// Traverse Show Alternative Courses
public void displayAllCourse() {
System.out.println(" All alternative course information: ");
for (Course course : courses) {
System.out.println(course.toString());
}
}
// Query alternative courses based on course number
public void queryCourse() {
System.out.println(" Please enter the course number to be queried: ");
String str = in.next();
System.out.println(str);
System.out.println((map.containsKey(str) ? "yes" : "no"));
System.out.println(map.get(str));
}
// Show selected courses
public void display() {
System.out.println(" Selected courses: ");
st.travese();
}
// Add selected courses
public void addSelect() {
System.out.println(" Enter the course number of the selected course, enter end End ");
while (true) {
String id = in.nextLine();
if (!id.equals("end")) {
Course cr = map.get(id);
st.getCourses().add(cr);
System.out.println(" Course Selection Success ");
} else {
// System.out.println(" End of Add ");
break;
}
}
}
// Reduce the number of courses selected
public void deleteSelect() {
System.out.println(" To delete the course number of the course, enter end End ");
while (true) {
String id = in.nextLine();
if (!id.equals("end")) {
Course cr = map.get(id);
st.getCourses().remove(cr);
System.out.println(" Delete succeeded ");
} else {
// System.out.println(" End of Add ");
break;
}
}
}
public void close() {
in.close();
}
}
// Test Class
package selectCourse;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
//~~~~~~~~~~~~~ Test management side ~~~~~~~~~~~~~~~~~~~~~~~~~~
/* Add Students
AdministratorOp a1=new AdministratorOp();
a1.add();
//a1.display1();
// a1.close();
a1.save1();*/
/* Add Course
AdministratorOp a2=new AdministratorOp();
a2.add2();
//a2.display2();
a2.close();
a2.save2();*/
/* // Test Delete, Find, Modify
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();*/
//~~~~~~~~~~~~~~~~ Test Student Side ~~~~~~~~~~~~~~~~~~~~~~~~~
/*Scanner in=new Scanner(System.in);
System.out.println(" Please enter a number: ");
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();
*/ }
}