Java学生选课实例之管理

course.java

package com.imooc.collection;
/*
 * 课程类
 */
public class course {
	
	public String id;
	
	public String name;

	public course(String id,String name){
		this.id=id;
		
		this.name=name;
	}
}

student.java

package com.imooc.collection;
import java.util.HashSet;
import java.util.Set;
/*
 * 学生类
 * 
 */
public class student {
	
	public String id;
	
	public String name;
	
	public Set<course> courses;
	
	public student(String id,String name){
		this.id=id;
		this.name=name;
		this.courses=new HashSet<course>();
	}
	
}

SetTest.java

package com.imooc.collection;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class SetTest {

	public List<course> courses;
	
	public SetTest (){
		this.courses = new ArrayList<course>();
	}
	
    public void TestAdd(){
		
		course cr1 = new course("1","数据结构");
		courses.add(cr1);
		course temp1 = (course)courses.get(0);
		System.out.println("添加了课程:"+temp1.id+temp1.name);
		
		course cr2 = new course("2","C语言");
		courses.add(1,cr2);
		course temp2 = (course)courses.get(1);
		System.out.println("添加了课程:"+temp2.id+temp2.name);

		
		course cr3 = new course("3","Java语言");
		courses.add(2,cr3);
		course temp3 = (course)courses.get(2);
		System.out.println("添加了课程:"+temp3.id+temp3.name);
		
		course[] cour1 = {new course("4","离散数学"),new course("5","汇编语言")};
		courses.addAll(3,Arrays.asList(cour1));
		course temp4 = (course)courses.get(3);
		course temp5 = (course)courses.get(4);
		System.out.println("添加了两门课程"+temp4.id+temp4.name+temp5.id+temp5.name);
		
		course[] cour2 = {new course("6","高等数学"),new course("7","线性代数")};
		courses.addAll(5,Arrays.asList(cour2));
		course temp6 = (course)courses.get(5);
		course temp7 = (course)courses.get(6);
		System.out.println("添加了两门课程"+temp6.id+temp6.name+temp7.id+temp7.name);
		
		course[] cour3 = {new course("8","高等数学"),new course("9","线性代数")};
		courses.addAll(7,Arrays.asList(cour3));
		course temp8 = (course)courses.get(7);
		course temp9 = (course)courses.get(8);
		System.out.println("添加了两门课程"+temp8.id+temp8.name+temp9.id+temp9.name);
		
	}
	
    /*
     * 通过ForEach遍历List的元素
     */
    public void  testForEach(){
		System.out.println("有如下课程待选(foreach访问)");
		for(course cr : courses){
			System.out.println(cr.id+cr.name);
		}
	}
    
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		SetTest st = new SetTest();
		st.TestAdd();
		st.testForEach();
		student stud = new student("1","小朱");
		System.out.println("欢迎学生 ： "+ stud.name + "选课！");
		Scanner input = new Scanner(System.in);
		
		for(int i = 0 ; i < 3 ; i++){
			System.out.println("请输入课程id");
			String courseId = input.nextLine();
			for(course cr : st.courses){
				if(cr.id.equals(courseId)){
					System.out.println(cr.id+cr.name);
				}
			}
		}
	}
	
	
}

set中添加某个对象，无论添加多少次最终只会保存第一次输入的那个对象