第5节 学生选课—添加课程(二)
<strong><span style="font-size:12px;">package com.imooc.collection;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
//备选课程类
public class ListTest {
/**
* 用于存放备选课程的List
* @param args
*/
public List coursesToSelect;
public ListTest(){
this.coursesToSelect=new ArrayList();//List是接口,实例化使用ArrayList类
}
public void testAdd(){
Course cr1=new Course("1","数据结构");
coursesToSelect.add(cr1);
Course temp=(Course)coursesToSelect.get(0);//对象存入集合都变成Object类型,取出时需要类型转换
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 temp1=(Course)coursesToSelect.get(0);
System.out.println("添加了课程"+temp1.id+":"+temp1.name);
//以下方法会抛出数组小标越界异常
//Course cr3=new Course("3","计算机网络");
//coursesToSelect.add(4,cr3);//目前数组长度为2,只能访问位置0、1,不能访问位置3
Course[] course={new Course("3","离散数学"),new Course("4","汇编语言")};
coursesToSelect.addAll(Arrays.asList(course));//将数组转换成List
Course temp2=(Course)coursesToSelect.get(2);
Course temp3=(Course)coursesToSelect.get(3);
System.out.println("添加了课程"+temp2.id+":"+temp2.name);
System.out.println("添加了课程"+temp3.id+":"+temp3.name);
Course[] course1={new Course("5","高等数学"),new Course("6","大学英语")};
coursesToSelect.addAll(2,Arrays.asList(course1));
Course temp4=(Course)coursesToSelect.get(2);
Course temp5=(Course)coursesToSelect.get(3);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("添加了课程"+temp4.id+":"+temp4.name);
System.out.println("添加了课程"+temp5.id+":"+temp5.name);
}
public static void main(String[] args) {
// TODO Auto-generated method stub
ListTest lt=new ListTest();
lt.testAdd();
}
}</span></strong>
运行结果: