java 对象排序

开发过程中，会遇到 对一个对象的序列进行排序。

java里面提供了Comparable、Comparator 接口

Comparable ： public int compareTo(T o);

Comparator ： int compareTo(T o1,T o2);

例子：

现在有一个类，有姓名、年龄两个属性，要求根据年龄排序

package cu.suning.min.demo.compareable;

import java.util.Comparator;

/**Comparable，数组排序
 * Comparator，list排序
 * @author 14051387
 *
 */
public class CompDemo implements Comparable<CompDemo> , Comparator<Object>{

	public String name;
	public int age;
	
	public CompDemo(){}
	
	public CompDemo(String name,int age){
		this.name = name;
		this.age = age;
	}
	// 数组排序
	@Override
	public int compareTo(CompDemo o) {
		if(this.age < o.getAge()){
			return -1;
		}else if(this.age > o.getAge()){
			return 1;
		}
		return 0;
	}
	// list排序用
	@Override
	public int compare(Object o1, Object o2) {
		CompDemo com1 = (CompDemo)o1;
		CompDemo com2 = (CompDemo)o2;
		if(com1.getAge() < com2.getAge()){
			return -1;
		}else if(com1.getAge() > com2.getAge()){
			return 1;
		}
		return 0;
	}
	
	public String toString(){
		return this.name+" , "+this.age; 
	}

	public String getName() {
		return name;
	}

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

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	
}

测试：

package cu.suning.min.demo.compareable;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class JmainTest {
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		CompDemo []com = new CompDemo[3]; 
		com[0] = new CompDemo("A", 47);
		com[1] = new CompDemo("B", 48); 
		com[2] = new CompDemo("C", 45); 
		
		List<CompDemo> lst = new ArrayList<CompDemo>();
		CompDemo comD = new CompDemo();
		for(CompDemo co : com){
			lst.add(co);
		}
		//******************************
		System.out.println("lst排序前:");
		System.out.println(lst);
		Collections.sort(lst, comD);
		System.out.println("lst排序后:");
		System.out.println(lst);
		// ***********************
		Arrays.sort(com);
		
		for(CompDemo co : com){
			System.out.println("排序后的数组：");
			System.out.println(co);
		}
	}

}