~~~ package com.imooc.collection; import java.util.ArrayList; import java.util.Arrays; import java.util.Iterator; import java.util.List; /** * 备选课程类 */ 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() { //创建一个课程对象,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); 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); System.out.println(coursesToSelect.size()); //以下方法会抛出数组下标越界异常 //Course cr3=new Course("3","test"); //coursesToSelect.add(4,cr3); Course[] course={new Course("3","离散数学"),new Course("4","汇编语言")}; coursesToSelect.addAll(Arrays.asList(course)); Course temp3= (Course) coursesToSelect.get(2); Course temp4= (Course) coursesToSelect.get(3); System.out.println("添加了两门课程:"+temp3.id+":"+temp3.name+";"+temp4.id+":"+temp4.name); Course[] course2={new Course("5","高等数学"),new Course("6","大学英语")}; coursesToSelect.addAll(Arrays.asList(course2)); Course temp6= (Course) coursesToSelect.get(4); Course temp7= (Course) coursesToSelect.get(5); System.out.println("添加了两门课程1:"+temp6.id+":"+temp6.name+";"+temp7.id+":"+temp7.name); } public void testGet(){ int size=coursesToSelect.size(); System.out.println("有如下课程待选:"); for (int i=0;i<size;i++){ Course cr= (Course) coursesToSelect.get(i); System.out.println("课程:"+cr.id+":"+cr.name); } } public static void main(String[] args) { ListTest lt=new ListTest(); lt.testAdd(); lt.testGet(); lt.testIterator(); lt.testModify(); lt.testForEach(); lt.testRemove(); } /** * 通过迭代器来遍历List */ public void testIterator(){ //通过集合的iterator方法,取得迭代器的实例 Iterator it=coursesToSelect.iterator(); System.out.println("有如下课程待选(通过迭代器访问)"); while (it.hasNext()) { Course cr= (Course) it.next(); System.out.println("课程:"+cr.id+":"+cr.name); } } /** * 通过for each方法访问集合元素 * */ public void testForEach(){ System.out.println("有如下课程待选(通过for each访问):"); for (Object obj:coursesToSelect) { Course cr= (Course) obj; System.out.println("课程:"+cr.id+":"+cr.name); } } /** * 修改List中的元素 */ public void testModify(){ coursesToSelect.set(4,new Course("7","毛概")); } /** * 删除List中的元素 */ public void testRemove(){ //一次删除一条记录 //Course cr= (Course) coursesToSelect.get(4); //System.out.println("我是课程:"+cr.id+":"+cr.name+",我即将被删除"); //coursesToSelect.remove(cr); //System.out.println("即将删除索引4位置上的课程!"); //coursesToSelect.remove(4); //批量删除 System.out.println("即将删除索引4位置和5位置上的课程!"); Course[] courses={ (Course) coursesToSelect.get(4), (Course) coursesToSelect.get(5) }; coursesToSelect.removeAll(Arrays.asList(courses)); System.out.println("成功删除课程!"); testForEach(); } } ~~~