java中排序實現簡單的策略模式
策略模式（Strategy Pattern）中體現了兩個非常基本的面向對象設計的原則
成賦值
java排序策略模式實現：
有這樣一個類：
public class Person {
private int id;
private String name;
private int age;
}
要求：假如有若干個類Person對象存在一個List當中，對他們進行排序，分別按照名字、
年齡、id 進行排序（要有正序與倒序兩種排序方式）。假如年齡或者姓名重復，按照id的正序進行排序。
以下為實現源代碼。
類Person
</b>package com.jack.SortStrategy;public class Person { private int id; private String name; private int age;
public Person(int id,String name,int age){ this.id=id; this.age=age; this.name=name; } /** * @return the id */ public int getId() { return id; } /** * @param id the id to set */ public void setId(int id) { this.id = id; } /** * @return the name */ public String getName() { return name; } /** * @param name the name to set */ public void setName(String name) { this.name = name; } /** * @return the age */ public int getAge() { return age; } /** * @param age the age to set */ public void setAge(int age) { this.age = age; }}</b></pre>
類IdOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class IdOrder implements Comparator<Person> {
@Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub return o1.getId()-o2.getId(); } public String getMethodName() { return "按id正序"; }}</b></pre>
類IdReverseOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class IdReverseOrder implements Comparator<Person> {
@Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub return o2.getId()-o1.getId(); } public String getMethodName() { return "按id逆序"; }}</b></pre>
類AgeOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class AgeOrder implements Comparator<Person> {
@Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o1.getAge()-(o2.getAge()); if(0==result){ //若年齡相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按年齡正序"; }}</b></pre>
類AgeReverseOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class AgeReverseOrder implements Comparator<Person> {
@Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o2.getAge()-(o1.getAge()); if(0==result){ //若年齡相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按年齡逆序"; }}</b></pre>
類NameOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class NameOrder implements Comparator<Person> {
@Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o1.getName().compareTo(o2.getName()); if(0==result){ //若姓名相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按姓名正序"; }}</b></pre>
類NameReverseOrder
package com.jack.SortStrategy;import java.util.Comparator;
public class NameReverseOrder implements Comparator<Person> { @Override public int compare(Person o1, Person o2) { // TODO Auto-generated method stub int result=o2.getName().compareTo(o1.getName()); if(0==result){ //若姓名相同按id排 return o1.getId()-o2.getId(); } return result; } public String getMethodName() { return "按姓名逆序"; } }</b></pre>
類Client
package com.jack.SortStrategy;import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.Iterator;
public class Client {
/** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub ArrayList<Person> personList = new ArrayList<Person>(); personList.add(new Person(1, "zhangsan", 20)); personList.add(new Person(2, "lisi", 21)); personList.add(new Person(3, "wangwu", 25)); personList.add(new Person(4, "zhaoliu", 26)); personList.add(new Person(5, "chenqi", 28)); personList.add(new Person(6, "dongba", 10)); personList.add(new Person(7, "zhansan", 15)); personList.add(new Person(8, "liujiu", 26)); /* * 可通過這里new不同的Comparator的實現從而實現不同的排序策略 * 分別有 * IdOrder：按Id正序 * IdReverseOrder：按Id逆序 * NameOrder：按姓名正序 * NameReverseOrder：按姓名逆序 * AgeOrder：按年齡正序 * AgeReverseOrder：按年齡逆序 */ Comparator<Person> comp = new IdOrder(); Collections.sort(personList, comp); System.out.println(((IdOrder)comp).getMethodName()+" 排序后的序列是:"); System.out.println("-----------------------"); for (Iterator<Person> itor=personList.iterator();itor.hasNext();) { Person p=itor.next(); System.out.println(p.getId() + " " +p.getName()+ " " + p.getAge()); } }}</b></pre>
執行Client可以得到排序的結果 </div>