Comparable 和 Comparator 区别以及应用，TreeSet和 List的 自动排序

实例Person01.class

package test01_集合添加的时候自动排序;

import java.util.Comparator;

/**
* @version 1.0
*
* @author DongXiang
*
* @action
* <br> <a> Comparator 不支持集合的排序功能 ，支持比较:compare(lso,rso);
* <br> <a> Comparable 支持集合的排序功能 :compareTo( o );
*
* <br> <a>针对于List 集合：1. 实现了Comparable接口的类的对象的方法，
* <br> <a> 2. Collections.sort或Arrays.sort进行自动排序。
* <br> <a>针对于Set(TreeSet) 集合：1. 实现了Comparable接口的类的对象的方法，
* <br> <a> 2. 重写equals 和 hashCode方法，再往集合中添加元素的时候，自动排序了；
*
* @time 2017年1月9日下午3:25:47
*
*/
public class Person01 implements Comparable<Person01>,Comparator<Person01>{

private String name;
private Integer age;
private Integer id;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}

public Person01() {
super();
}

public Person01(String name, Integer age, Integer id) {
super();
this.name = name;
this.age = age;
this.id = id;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", id=" + id + "]";
}

@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((age == null) ? 0 : age.hashCode());
result = prime * result + ((id == null) ? 0 : id.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Person01 other = (Person01) obj;
if (age == null) {
if (other.age != null)
return false;
} else if (!age.equals(other.age))
return false;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
@Override
public int compareTo(Person01 o) {
int tempAge=this.getAge().compareTo(o.getAge());
int tempID=this.getId().compareTo(o.getId());

return tempID==0?(tempAge==0?0:tempAge):tempID;
}
@Override
public int compare(Person01 o1, Person01 o2) {
int tempAge=o1.getAge().compareTo( o2.getAge());
int tempID=o1.getId().compareTo( o2.getId());

return tempID==0?(tempAge==0?0:tempAge):tempID;
}

}


应用Test01.class
package test01_集合添加的时候自动排序;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;

public class Test01 {

public static void main(String[] args) {
List<Person01> pList=new ArrayList<>();
Set<Person01> pSet=new TreeSet<>();
Map<String, Person01> pMap=new HashMap<>();

Person01 person03=new Person01("p3", 13, 20);
Person01 person01=new Person01("p1", 11, 21);
Person01 person02=new Person01("p2", 12, 22);
Person01 person07=new Person01("p7", 10, 20);
Person01 person04=new Person01("p3", 13, 20);
Person01 person06=new Person01("p6", 10, 25);
Person01 person05=new Person01("p5", 15, 20);

pList.add(person03);
pList.add(person01);
pList.add(person02);
pList.add(person07);
pList.add(person04);
pList.add(person06);
pList.add(person05);

pSet.add(person03);
pSet.add(person01);
pSet.add(person02);
pSet.add(person07);
pSet.add(person04);
pSet.add(person06);
pSet.add(person05);

pMap.put("person03", person03);
pMap.put("person01", person01);
pMap.put("person02", person02);
pMap.put("person07", person07);
pMap.put("person04", person04);
pMap.put("person06", person06);
pMap.put("person05", person05);

System.out.println("################ pList 遍历 ##########");

Collections.sort(pList);//调用这个方法的时候，按照集合重写的comparable的方法，自动按照排序规则；进行排序。

for (Iterator iterator = pList.iterator(); iterator.hasNext();) {
Person01 person012 = (Person01) iterator.next();
System.out.println(person012.toString());
}

System.out.println("################ pSet 遍历 ##########");
//重写equals 和 hashCode，和Implements Comparable自动按照排序规则；进行排序。

for (Iterator iterator = pSet.iterator(); iterator.hasNext();) {
Person01 person012 = (Person01) iterator.next();
System.out.println(person012.toString());

}

System.out.println("################ pMap 遍历 ##########");
// Set keySet=pMap.keySet();
// for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
// String key = (String) iterator.next();
// System.out.println("key = "+key+";keyValue = "+pMap.get(key));
// }

// System.out.println("通过Map.values()遍历所有的value，但不能遍历key");
// for (Person01 v : pMap.values()) {
// System.out.println("value= " + v);
// }
for (Map.Entry<String, Person01> entry : pMap.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}

}

}