Guava ---- Ordering排序工具

使用Guava的排序工具类，快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> {@Overridepublic 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();// 根据第二个参数排序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);/*** 单参数排序*/// 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");/*** 多参数排序*/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> {@Overridepublic int compare(City city1, City city2) {return Doubles.compare(city1.getAverageRainfall(), city2.getAverageRainfall());}
}

输出结果：

参考资料：

《Getting Started with Google Guava》

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