Ordering排序工具一

迈不过友情╰ 2022-04-10 06:17 118阅读 0赞

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> {
     
    	@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();
     
    		// 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> {
    	@Override
    	public int compare(City city1, City city2) {
    		return Doubles.compare(city1.getAverageRainfall(), city2.getAverageRainfall());
    	}
    }

输出结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjg2ODYzOA_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjg2ODYzOA_size_16_color_FFFFFF_t_70]: /images/20220402/f80b455be2e24f9bb1a271bc8ab8d030.png