yL_human
2016-03-19 23:45
package com.imooc;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
//备选课程类
public class ListTest {
//用于存放课程的书架
public List coursesToSelect;
public ListTest(){
this.coursesToSelect = new ArrayList();
}
//用于往课表里添加课程
public void testAdd(){
//创建课程对象,通过add方法添加课程到课程表里
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.getId() +":"+ temp.getName());
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.getId() +":"+ temp2.getName());
coursesToSelect.add(cr1);
//
Course temp0 = (Course)coursesToSelect.get(2);
System.out.println("添加了课程:"+temp0.getId() +":"+ temp0.getName());
//注释的方法会引起数组下标越界异常
// Course cr3 = new Course("3","test");
// coursesToSelect.add(3, cr3);
Course[] cr3 = {new Course("3","离散数学"),new Course("4","数学")};
coursesToSelect.addAll(Arrays.asList(cr3));
Course temp3 = (Course)coursesToSelect.get(3);
Course temp4 = (Course)coursesToSelect.get(4);
System.out.println("添加了课程:"+temp3.getId() +":"+ temp3.getName()+
temp4.getId() +":"+ temp4.getName());
Course[] cr4 = {new Course("5","线性数学"),new Course("6","大数学")};
coursesToSelect.addAll(2, Arrays.asList(cr4));
Course temp5 = (Course)coursesToSelect.get(2);
Course temp6 = (Course)coursesToSelect.get(3);
System.out.println("添加了课程:"+temp5.getId() +":"+ temp5.getName()+
temp6.getId() +":"+ temp6.getName());
}
//通过for each方法访问集合元素
public void testFof(){
System.out.println("有如下课程选择通过for each访问:");
for(Object obj : coursesToSelect){
Course cr = (Course) obj;
System.out.println("课程:"+cr.getId()+":"+cr.getName());
}
}
//删除list中的元素
public void testRemove(){
// Course cr = (Course) coursesToSelect.get(4);
System.out.println("即将删除4位置上的元素");
coursesToSelect.remove(4);
System.out.println("成功删除");
testFof();
//通过removeAll方法删除元素
Course[] courses = {(Course) coursesToSelect.remove(1)
,(Course) coursesToSelect.remove(2)};
coursesToSelect.remove(Arrays.asList(courses));
System.out.println("即将删除1和2位置的元素");
testFof();
}
public static void main(String[] args) {
ListTest lt= new ListTest();
lt.testAdd();
// lt.testGet();
// lt.testIt();
// lt.testFof();
// lt.testModify();
lt.testFof();
lt.testRemove();
}
}
数组排序是从0开始的,你删除的2位置实际上是第三个数组元素,即大数学。
这应该是get()吧!
Java入门第三季
409767 学习 · 4530 问题
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