个回答

• Pikachu2016

  2019-08-13 12:58:05

  感觉最后多了个 }

  0

• 慕慕3524473

  2019-04-10 23:24:37

  你把testForEachForSet方法放到main方法前面试试

  0

• 慕容9086035

  2019-03-13 17:29:32

  package com.test.collection;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Scanner;
  
  public class SetTest {
  
      public List<Course> coursesToSelect;
      //构造器
      public SetTest(){
          coursesToSelect=new ArrayList<Course>();
      }
  
  /*    public static class List_Test {
          //用于存放备选课程的List
          public List coursesToSelect;
  
          public List_Test(){
              this.coursesToSelect=new ArrayList();
          }
          }*/
          //用于网coursesToSelet中添加备选课程
          public void testAdd(){
              //创建一个课程对象，并通过调用add方法，添加到备选课程中
              Course cr1=new Course("1","数据结构");
              coursesToSelect.add(cr1);
              Course temp= (Course) coursesToSelect.get(0);
              //System.out.println("添加了课程："+temp.id+";"+temp.name);
  
  
              Course cr2=new Course("2","C语言");
              coursesToSelect.add(0,cr2);
              Course temp2= (Course) coursesToSelect.get(0);
              //System.out.println("添加了课程："+temp2.id+";"+temp2.name);
  
              //coursesToSelect.add(cr1);
              //Course temp0= (Course) coursesToSelect.get(2);
              //System.out.println("添加了课程："+temp.id+";"+temp.name);
  
              //下面方法会抛出数组下标越界异常
              // Course cr3=new Course("3","test");
              //coursesToSelect.add(4,cr3);
  
              Course[] courses={new Course("3","离散数学"),new Course("4","汇编语言")};
              coursesToSelect.addAll(Arrays.asList(courses));
              Course temp3= (Course) coursesToSelect.get(3);
              Course temp4= (Course) coursesToSelect.get(4);
  
              //System.out.println("添加了两门课程："+temp3.id+";"+temp.name+";"+temp4.id+";"+temp4.name);
  
              Course[] courses2={new Course("5","高等数学"),new Course("6","大学英语")};
              coursesToSelect.addAll(2,Arrays.asList(courses2));
              Course temp5= (Course) coursesToSelect.get(2);
              Course temp6= (Course) coursesToSelect.get(3);
              //System.out.println("添加了两门课程："+temp5.id+";"+temp5.name+";"+temp6.id+";"+temp6.name);
  
          }
  
  
          /*
          for each方法访问集合元素  更好
           */
          public void testForEach(){
              System.out.println("有如下课程待选（通过foreach访问：");
              for (Object obj:coursesToSelect){
                  Course cr=(Course)obj;
                  System.out.println("课程："+cr.id+";"+cr.name);
              }
          }
  
  
      public static void main(String[] args) {
              SetTest st=new SetTest();
              st.testAdd();
              st.testForEach();
              Student student=new Student("1","小埋");
          System.out.println("欢迎学生 "+student.name+"选课");
          //创建一个scanner对象，用来接收从键盘输入的课程ID
          Scanner console=new Scanner(System.in);
  
          for (int i=0;i<3;i++){
              System.out.println("输入课程ID");
              String courseId=console.next();
              for (Course cr:st.coursesToSelect){
                  if (cr.id.equals(courseId)){
                      student.courses.add(cr);
                  }
              }
          }
          st.testForEachForSet(student);
      }
      public void testForEachForSet(Student student){
              //打印输出 学生所选的课程
          System.out.println("xuanle" +student.courses.size()+"ke");
          for (Course cr:student.courses){
              System.out.println("选择了课程 "+cr.id+":"+cr.name);
          }
      }
      }

  
  

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