package com.imooc.collection;

import java.util.ArrayList;

import java.util.List;

/**

?* 備選課程類

?* @author sss

?*

?*/

public class ListTest {

? ? /**

? ? ?* 用于存放備選課程的List

? ? ?*/

public List courseToSelect;

public ListTest(){

this.courseToSelect = new ArrayList();

}

/**

* 用于往courseToSelect中添加備選課程?

*/

public void testAdd(){

//創(chuàng)建一個(gè)課程對(duì)象，并通過(guò)調(diào)用add方法。添加到備選課程List中

Course cr1 = new Course("1","數(shù)據(jù)結(jié)構(gòu)");

courseToSelect.add(cr1);

Course temp = (Course) courseToSelect.get(0);

System.out.println("添加了課程："+temp.id+":"+temp.name );

Course cr2 = new Course("2","C語(yǔ)言");

courseToSelect.add(0,cr2);

Course temp2 = (Course) courseToSelect.get(0);

System.out.println("添加了課程："+temp2.id+":"+temp2.name);

}

public static void main(String[] args){

ListTest lt = new ListTest();

lt.testAdd();

}

}

輸出結(jié)果為 ?

添加了課程：數(shù)據(jù)結(jié)構(gòu):null

添加了課程：C語(yǔ)言:null

? ?怎么和老師的不同？