cololection
package cn.bjsxt.col;
/**
* 简化迭代器原理
* hasNext
* next
* @author Administrator
*
*/
public class MyArrayList {
private String[] elem ={"a","b","c","d","e","f","g"};
private int size = elem.length; private int cursor =-1;
/**
* 判断是否存在下一个元素
* @return
*/
public boolean hasNext(){
return cursor+1<size;
}
/**
* 获取下一个元素
*/
public String next(){
cursor++; //移动一次
return elem[cursor];
}
/**
* 删除元素
*/
public void remove(){ } /**
* @param args
*/
public static void main(String[] args) {
MyArrayList list = new MyArrayList();
while(list.hasNext()){
System.out.println(list.next());
} list = new MyArrayList();
while(list.hasNext()){
System.out.println(list.next());
}
} }
package cn.bjsxt.col; import java.util.Iterator; /**
* 简化迭代器原理 加入接口 提供方法
* hasNext
* next
* @author Administrator
*
*/
public class MyArrayList2 {
private String[] elem ={"a","b","c","d","e","f","g"};
private int size = elem.length; private class MyIt implements Iterator<String>{
private int cursor =-1;
/**
* 判断是否存在下一个元素
* @return
*/
public boolean hasNext(){
return cursor+1<size;
}
/**
* 获取下一个元素
*/
public String next(){
cursor++; //移动一次
return elem[cursor];
}
/**
* 删除元素
*/
public void remove(){
//没有实现
} } public Iterator<String> iterator(){
return new MyIt();
} /**
* @param args
*/
public static void main(String[] args) {
MyArrayList2 list = new MyArrayList2();
Iterator<String> it =list.iterator();
while(it.hasNext()){
System.out.println(it.next());
} it =list.iterator();
while(it.hasNext()){
System.out.println(it.next());
} } }
package cn.bjsxt.col; import java.util.Iterator; /**
* 简化迭代器原理 加入接口 提供方法
* hasNext
* next
* @author Administrator
*
*/
public class MyArrayList3 implements java.lang.Iterable<String> {
private String[] elem ={"a","b","c","d","e","f","g"};
private int size = elem.length; /**
* 匿名内部类
* @return
*/
public Iterator<String> iterator(){
return new Iterator<String>(){
private int cursor =-1;
/**
* 判断是否存在下一个元素
* @return
*/
public boolean hasNext(){
return cursor+1<size;
}
/**
* 获取下一个元素
*/
public String next(){
cursor++; //移动一次
return elem[cursor];
}
/**
* 删除元素
*/
public void remove(){
//没有实现
} };
} /**
* @param args
*/
public static void main(String[] args) {
MyArrayList3 list = new MyArrayList3();
Iterator<String> it =list.iterator();
while(it.hasNext()){
System.out.println(it.next());
it.remove(); //删除元素
} it =list.iterator();
while(it.hasNext()){
System.out.println(it.next());
}
System.out.println("增强for，必须实现java.lang.Iterable接口，重写iterator方法");
for(String temp:list){
System.out.println(temp); } } }
package cn.bjsxt.map; import java.util.HashMap;
import java.util.Map;
import java.util.Set; /**
* this is a cat and that is a mice and where is the food?
* 统计每个单词出现的次数
*
* 存储到Map中
* key :String
* value:自定义类型
*
* "分拣" 思路
* 1、为所有key创建容器
* 之后容器中存放对应value
* 2、第一次创建容器，并存放值value
* 第二次之后，直接使用容器存放值
* @author Administrator
*
*/
public class Demo01 { /**
* @param args
*/
public static void main(String[] args) {
String str ="this is a cat and that is a mice and where is the food";
//分割字符串
String[] strArray=str.split(" ");
//存储到Map中
Map<String,Letter> letters = new HashMap<String,Letter>();
for(String temp:strArray){
/*
//1、为所有key创建容器
if(!letters.containsKey(temp)){
Letter col = new Letter();
col.setCount(1); //第一次值存放容器中
letters.put(temp, col);
}else{
//2、 第二次之后，直接使用容器存放值
Letter col =letters.get(temp); //直接使用容器
col.setCount(col.getCount()+1);
}*/
Letter col = null;
if(null==(col=letters.get(temp))){
col = new Letter();
col.setCount(1); //第一次值存放容器中
letters.put(temp, col);
}else{
//2、 第二次之后，直接使用容器存放值
col.setCount(col.getCount()+1);
}
}
//输出Map的值
Set<String> keys = letters.keySet();
for(String key:keys){
Letter col =letters.get(key);
System.out.println("字母:"+key+",次数"+col.getCount());
} }
public static void test1(){
String str ="this is a cat and that is a mice and where is the food";
//分割字符串
String[] strArray=str.split(" ");
//存储到Map中
Map<String,Letter> letters = new HashMap<String,Letter>();
/*
for(String temp:strArray){ //1、为所有key创建容器
之后容器中存放对应value if(!letters.containsKey(temp)){
letters.put(temp, new Letter());
}
}
for(String temp:strArray){ // 容器中存放对应value Letter col =letters.get(temp); //直接使用容器
col.setCount(col.getCount()+1);
} */
for(String temp:strArray){ //1、为所有key创建容器
if(!letters.containsKey(temp)){
letters.put(temp, new Letter());
}
//2、 之后容器中存放对应value
Letter col =letters.get(temp); //直接使用容器
col.setCount(col.getCount()+1);
} //输出Map的值
Set<String> keys = letters.keySet();
for(String key:keys){
Letter col =letters.get(key);
System.out.println("字母:"+key+",次数"+col.getCount());
}
}
}
package cn.bjsxt.map;
public class Letter {
private String name;
private int count;
public Letter() {
// TODO Auto-generated constructor stub
}
public Letter(String name, int count) {
super();
this.name = name;
this.count = count;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
}
package cn.bjsxt.map;
public class Student {
private String name;
private String no;
private double score;
public Student() {
}
public Student(String name, String no, double score) {
super();
this.name = name;
this.no = no;
this.score = score;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNo() {
return no;
}
public void setNo(String no) {
this.no = no;
}
public double getScore() {
return score;
}
public void setScore(double score) {
this.score = score;
}
@Override
public String toString() {
return "Student [name=" + name + ", no=" + no + ", score=" + score
+ "]";
}
}
package cn.bjsxt.map; import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set; /**
* 定义一个Student类,属性:name 姓名,classNumber 班号,score 成绩
现在将若干Student对象放入List,请统计出每个班级的总分和平均分,分别打印出来
以面向对象的思维解决
* @author Administrator
*
*/
public class MapDemo03 {
public static void main(String[] args) {
List<Student> list = new ArrayList<Student>();
exam(list); //统计
Map<String,ClassRoom> rooms = new HashMap<String,ClassRoom>();
count(rooms,list);
//打印
printScore(rooms);
} /**
* 打印 总分与平均分
*/
public static void printScore(Map<String,ClassRoom> rooms){
Set<Map.Entry<String,ClassRoom>> entrySet =rooms.entrySet();
Iterator<Map.Entry<String,ClassRoom>> it =entrySet.iterator();
while(it.hasNext()){
Map.Entry<String,ClassRoom> entry =it.next();
ClassRoom room = entry.getValue();
double avg = room.getTotal()/room.getStus().size();
System.out.println("班号为:"+room.getNo()+",总分"+room.getTotal()+",平均分"+avg);
}
} /**
* 统计分数
*/
public static void count(Map<String,ClassRoom> rooms,List<Student> list){
for(Student stu:list){
String no = stu.getNo();
double score = stu.getScore();
//根据班级编号 查看 Map是否存在该班级 分拣思路
ClassRoom room = rooms.get(no);
if(null==room){ //第一次
room = new ClassRoom(no);
rooms.put(no, room);
}
//存储 总分
room.setTotal(room.getTotal()+score);
room.getStus().add(stu); //加入学生
}
} /**
* 现在将若干Student对象放入List
* @param list
*/
public static void exam(List<Student> list){
list.add(new Student("a","001",80));
list.add(new Student("b","001",80));
list.add(new Student("a","002",80));
list.add(new Student("c","003",80));
list.add(new Student("d","003",80));
}
}
package cn.bjsxt.map; import java.util.ArrayList;
import java.util.List; /**
* 班级
* @author Administrator
*
*/
public class ClassRoom {
private String no;
private List<Student> stus; //学生列表
private double total; //总分
public ClassRoom() {
stus = new ArrayList<Student>();
} public ClassRoom(String no) {
this();
this.no = no;
}
public String getNo() {
return no;
}
public void setNo(String no) {
this.no = no;
}
public List<Student> getStus() {
return stus;
}
public void setStus(List<Student> stus) {
this.stus = stus;
}
public double getTotal() {
return total;
}
public void setTotal(double total) {
this.total = total;
} }
cololection的更多相关文章
随机推荐
- plateform_driver_register和plateform_device_register区别
设备与驱动的两种绑定方式:在设备注册时进行绑定及在驱动注册时进行绑定. 以一个USB设备为例,有两种情形: (1)先插上USB设备并挂到总线中,然后在安装USB驱动程序过程中从总线上遍历各个设备,看驱 ...
- IOS开发之──应用之间调用（1）
iphone应用之间调用步骤: 1)在plist文件中,注册对外接口 在xcode group&files 里面,展开 resources选择<app>info.plist 鼠标右 ...
- 自定义控件(模仿微信ToggleButton控件)
弄过android开发的都知道,系统有一个默认的ToggleButton,但很多人都觉得他很难看,当然也包括我.如果你感觉他不难看,那你就继续使用系统的吧,这篇文章对你来说是多余的了. 今天来写一个模 ...
- verilog逻辑复制
本文转自:http://www.cnblogs.com/linjie-swust/archive/2012/03/27/FPGA_verilog.html 在FPGA设计中经常使用到逻辑复制,逻辑复制 ...
- hbase meta表修复
meta表修复一 查看hbasemeta情况hbase hbck1.重新修复hbase meta表(根据hdfs上的regioninfo文件,生成meta表)hbase hbck -fixMeta2. ...
- 初见IOS的UI之：UI控件的属性frame bounds center 和transform
这些属性,内部都是结构体:CGRect CGPoint CGFloat 背景知识:所有的控件都是view的子类,屏幕就是一个大的view:每个view都有个viewController,它是view的 ...
- Uyuw's Concert POJ2451
裸半平面交,以前没写过,先写一遍再说 我越来越不注意细节了,最后才发现空间稍微开小了(没有开那个零头,他又要多4条边,就WA了) const maxn=; eps=1e-7; type point=r ...
- java,图片压缩,略缩图
在网上找了两个图片的缩放类,在这里分享一下: package manager.util; import java.util.Calendar; import java.io.File; import ...
- angular入门系列教程3
主题: 本篇主要目的就是继续完善home页,增加tab导航的三个页index index1 index2 效果图: 细节: 初始化的JS就是咱们的home.js,仔细来看. angular的route ...
- dede首页调用栏目内容{dedefield.content}的方法
Dedecms的功能确实很强大,但是dedecms的全局变量有字节限制,使得我们在使用dedecms制作企业站的时候,首页无法调用大段大段的企业站. 其实dedecms还有另外一种调用大段内容的方法, ...