2.添加课程I

package com.imooc.collection;

import java.util.ArrayList;
import java.util.List;

/**
 * 备选课程类
 *
 * @author Administrator
 *
 */
public class ListTest {
    /*
     * 用于存放备选课程的List
     */
    public List coursesToSelect;

    public ListTest() {
        this.coursesToSelect = new ArrayList();
    }

    /*
     * 用于往coursesToSelect中添加备选课程
     */
    public void testAdd() {
        // 创建一个对象，并通过调用add方法，添加到备选课程List中
        Course cr1 = new Course("1", "数据结构");
        coursesToSelect.add(cr1);
        // 注意：对象存入集合都变成Object类型，取出时需要类型转换，强转
        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);

        Course cr3 = new Course("3","test");
        //        Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 4, Size: 2
        coursesToSelect.add(4, cr3);
    }

    public static void main(String[] args) {
        ListTest lt = new ListTest();
        lt.testAdd();
    }
}