JAVA中的集合

List总结：

1. 所有的List中只能容纳单个不同类型的对象组成的表，而不是Key－Value键值对。例如：[ tom,1,c ]；

2. 所有的List中可以有相同的元素，例如Vector中可以有 [ tom,koo,too,koo ]；

3. 所有的List中可以有null元素，例如[ tom,null,1 ]；

4. 基于Array的List（Vector，ArrayList）适合查询，而LinkedList（链表）适合添加，删除操作。

Set总结：

1. Set实现的基础是Map（HashMap）；

2.  Set中的元素是不能重复的，如果使用add(Object obj)方法添加已经存在的对象，则会覆盖前面的对象

Map映射
映射与集或列表有明显区别，映射中每个项都是成对的。映射中存储的每个对象都有一个相关的关键字（Key）对象，关键字决定了对象在映射中的存储位置，检索对象时必须提供相应的关键字，就像在字典中查单词一样。关键字应该是唯一的。

以下是集合打出相应的部门

Department.java类

package com.collection;

import java.util.List;
import java.util.Map;
import java.util.Set;

public class Department {
    public String name ;
    public String empName[];
    public List<Employ> empList;
    public Set<Employ> empSet;
    public Map<String,Employ> empMap;
    public Map<String, Employ> getEmpMap() {
        return empMap;
    }
    public void setEmpMap(Map<String, Employ> empMap) {
        this.empMap = empMap;
    }
    public Set<Employ> getEmpSet() {
        return empSet;
    }
    public void setEmpSet(Set<Employ> empSet) {
        this.empSet = empSet;
    }
    public List<Employ> getEmpList() {
        return empList;
    }
    public void setEmpList(List<Employ> empList) {
        this.empList = empList;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String[] getEmpName() {
        return empName;
    }
    public void setEmpName(String[] empName) {
        this.empName = empName;
    }

}

Employ.java类

package com.collection;

public class Employ {
    public String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

TestCollection.java类

package com.collection;

import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestCollection {

    /**
     * @param args
     */
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("com/collection/beans.xml");
        Department department = (Department)ac.getBean("department");
        System.out.println(department.getName());
        for(String emp:department.getEmpName()){
            System.out.println(emp);
        }
        System.out.println("..................");
        for(Employ e:department.getEmpList()){
            
            System.out.println(e.getName());
        }
        System.out.println("..................");
        for(Employ e:department.getEmpSet()){
            
            System.out.println(e.getName());
        }
        
33         Map<String,Employ> employee = department.getEmpMap();
34         Iterator it = employee.keySet().iterator();
35         while(it.hasNext()){
36             String key = (String) it.next();
37             Employ emp = employee.get(key);
38             System.out.println("迭代器--"+key+emp.getName());
39         }
40         
41         System.out.println("..................");
42         for(Entry<String, Employ> entry:department.getEmpMap().entrySet()){
43             System.out.println(entry.getKey()+" "+entry.getValue().getName());
44         }
    }

}

 beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="department" class="com.collection.Department">
    <property name="name" value="往事" />
    <property name="empName">
    <list>
        <value>网络</value>
        <value>设施</value>
        <value>软件</value>
    </list>
    </property>
    <property name="empList">
        <list>
            <ref bean="emp1"/>
            <ref bean="emp2"/>
        </list>
    </property>
        <property name="empSet">
        <set>
            <ref bean="emp1"/>
            <ref bean="emp2"/>
        </set>
    </property>
    <property name="empMap">
        <map>
            <entry key="1" value-ref="emp1"></entry>
            <entry key="2" value-ref="emp2"></entry>
        </map>
    </property>
</bean>

<bean id="emp1" class="com.collection.Employ">
    <property name="name" value="张三" />
</bean>
<bean id="emp2" class="com.collection.Employ">
    <property name="name" value="李斯" />
</bean>
</beans>