JAVA学习.JAVA集合类型Map.HashMap&TreeMap

以下是一张比较简单的介绍图，在具体代码分析之前先大概的了解以下要介绍的内容。

作为key值保存的类对象：

/** *  */package MapDemo;/** * @author fshxxxyydys * */public class Dog implements Comparable<Dog>{private String color;private Integer age;public Dog() {super();}public Dog(String color, Integer age) {super();// 子类构造方法调用父类构造方法只能放在第一行this.color = color;this.age = age;}//如果有需要可以根据需要填写不同参数的构造函数public String getColor() {return color;}public void setColor(String color) {this.color = color;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic boolean equals(Object obj) {if(obj == null) return false;if(obj == this) return true;if(!(obj instanceof Dog)) return false;Dog d =(Dog)obj;if(this.age.equals(d.age)&&this.color.equals(d.color))return true;return false;}@Overridepublic int hashCode() {return  this.color.hashCode() + this.age.hashCode();}@Overridepublic int compareTo(Dog o) {//传进来的对象本身就是指定对象类型无需进行判断if(this.age.compareTo(o.age) != 0){return this.age.compareTo(o.age);}//先按照年龄来排序if(this.color.compareTo(o.color) != 0){return this.color.compareTo(o.color);}//再按照颜色来排序return 0;//如果颜色和年龄都相同返回0的就按照相同处理}@Overridepublic String toString() {return "Color:" + this.color + " Age:" + this.age + ".";}}

TreeMap：

/** *  */package MapDemo;import java.util.Set;import java.util.TreeMap;/** * @author fshxxxyydys * */public class TreeMapDemo {/** * @param args */public static void main(String[] args) {//TreeMap是以TreeSet来进行key管理的Map接口的实现//与TreeSet类似，如要使得TreeMap对其key值进行无//重复的筛选以及自然顺序排序，则被当做key值得对象//必须实现Comparable接口并实现CompareTo方法.TreeMap<Dog,String> dogMap = new TreeMap<Dog,String>();dogMap.put(new Dog("bule",11),"A");dogMap.put(new Dog("bule",12),"B");dogMap.put(new Dog("bule",10),"C");dogMap.put(new Dog("red",1),"D");dogMap.put(new Dog("red",21),"E");dogMap.put(new Dog("red",4),"F");dogMap.put(new Dog("green",8),"G");dogMap.put(new Dog("green",12),"H");dogMap.put(new Dog("green",4),"I");Set<Dog> dogKey = dogMap.keySet();//获取dogMap中key的Set值。        for(Dog d:dogKey)        System.out.println(d);}}

======================================================================

Result：

Color:red Age:1.
Color:green Age:4.
Color:red Age:4.
Color:green Age:8.
Color:bule Age:10.
Color:bule Age:11.
Color:bule Age:12.
Color:green Age:12.
Color:red Age:21.

======================================================================

HashMap：

/** *  */package MapDemo;import java.util.HashMap;import java.util.Set;/** * @author fshxxxyydys * */public class HashMapDemo {/** * @param args */public static void main(String[] args) {HashMap<Dog,String> dogMap = new HashMap<Dog,String>();dogMap.put(new Dog("bule",11),"A");dogMap.put(new Dog("bule",12),"B");dogMap.put(new Dog("bule",10),"C");dogMap.put(new Dog("red",1),"D");dogMap.put(new Dog("red",21),"E");dogMap.put(new Dog("red",4),"F");dogMap.put(new Dog("green",8),"G");dogMap.put(new Dog("green",12),"H");dogMap.put(new Dog("green",4),"I");        for(Dog d:dogMap.keySet())        System.out.println(d);}}

======================================================================

Result：

Color:red Age:1.
Color:green Age:4.
Color:red Age:4.
Color:red Age:21.
Color:bule Age:12.
Color:bule Age:11.
Color:bule Age:10.
Color:green Age:12.
Color:green Age:8.

======================================================================

原创出处：http://blog.csdn.net/u012830807