使用Guava的排序工具类， 高速实现对象的单变量排序和多变量排序， 让你的开发效率爆炸...

import com.google.common.collect.Lists;

import com.google.common.collect.Ordering;

import com.google.common.primitives.Ints;

import java.util.Collections;

import java.util.Comparator;

import java.util.Iterator;

import java.util.List;

public class CityByPopluation implements Comparator<City> {

	@Override

	public int compare(City city1, City city2) {

		return Ints.compare(city1.getPopulation(), city2.getPopulation());

	}

	public static void main(String[] args) {

		CityByPopluation cityByPopluation = new CityByPopluation();

		CityByRainfall cityByRainfall = new CityByRainfall();

		// 依据第二个參数排序

		City city1 = new City("Beijing", 100000, 55.0);

		City city2 = new City("Shanghai", 100000, 45.0);

		City city3 = new City("ShenZhen", 100000, 33.8);

		List<City> cities = Lists.newArrayList(city1, city2, city3);

		/**

		 * 单參数排序

		 */

		// 排序反转

		Ordering<City> firstOrdering = Ordering.from(cityByRainfall).reverse();

		Collections.sort(cities, firstOrdering);

		Iterator<City> cityByRainfallIterator = cities.iterator();

		while (cityByRainfallIterator.hasNext()) {

			System.out.println(cityByRainfallIterator.next().getCityName());

		}

		System.out.println("I was evil dividing line");

		/**

		 * 多參数排序

		 */

		Ordering<City> secondaryOrdering = Ordering.

				from(cityByPopluation).compound(cityByRainfall);

		Collections.sort(cities, secondaryOrdering);

		Iterator<City> cityIterator = cities.iterator();

		while (cityIterator.hasNext()) {

			System.out.println(cityIterator.next().getCityName());

		}

		/**

		 * 取得最小最大值

		 */

		Ordering<City> ordering = Ordering.from(cityByRainfall);

		// 降雨量最高的2个城市

		List<City> topTwo = ordering.greatestOf(cities, 2);

		Iterator<City> topTwoIterator = topTwo.iterator();

		while (topTwoIterator.hasNext()) {

			System.out.println("降雨量最高城市" + topTwoIterator.next().getCityName());

		}

		// 降雨量最低的一个城市

		List<City> bottomOne = ordering.leastOf(cities, 1);

		Iterator<City> bottomOneIterator = bottomOne.iterator();

		while (bottomOneIterator.hasNext()) {

			System.out.println("降雨量最低的城市" + bottomOneIterator.next().getCityName());

		}

	}

}

City类：

/**

 * Created by wenniuwuren on 2015/6/4.

 */

public class City {

	private String cityName;

	private Integer population;

	private Double averageRainfall;

	public City(String cityName, Integer population, Double averageRainfall) {

		this.cityName = cityName;

		this.population = population;

		this.averageRainfall = averageRainfall;

	}

	public String getCityName() {

		return cityName;

	}

	public void setCityName(String cityName) {

		this.cityName = cityName;

	}

	public Integer getPopulation() {

		return population;

	}

	public void setPopulation(Integer population) {

		this.population = population;

	}

	public Double getAverageRainfall() {

		return averageRainfall;

	}

	public void setAverageRainfall(Double averageRainfall) {

		this.averageRainfall = averageRainfall;

	}

}

CityByRainfall类：

import com.google.common.primitives.Doubles;

import java.util.Comparator;

public class CityByRainfall implements Comparator<City> {

	@Override

	public int compare(City city1, City city2) {

		return Doubles.compare(city1.getAverageRainfall(), city2.getAverageRainfall());

	}

}

输出结果：

參考资料：

《Getting Started with Google Guava》