Google Guava学习（3）-Guava Ordering类

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1. 功能：排序

2. 代码：

package com.example.google.guava.demo.clazz;import com.google.common.collect.Ordering;import java.util.ArrayList;import java.util.Collections;import java.util.List;/** * <p> * <code>OrderingTest</code> * </p> * Description: * * @author Mcchu * @date 2017/10/18 16:54 */public class OrderingTest {    public static void main(String[] args) {        List<Integer> numList = new ArrayList<>();        numList.add(5);        numList.add(30);        numList.add(25);        numList.add(10);        numList.add(15);        System.out.println("排序前："+numList);        // 1.自然排序，由小到大        Ordering ordering = Ordering.natural();        Collections.sort(numList,ordering);        System.out.println("自然排序："+numList);        // 2.判断是否有序，最小值，最大值        Boolean bol = ordering.isOrdered(numList);        Integer minValue = (Integer) ordering.min(numList);        Integer maxValue = (Integer) ordering.max(numList);        System.out.println("是否已排序："+bol);        System.out.println("最小值："+minValue);        System.out.println("最大值："+maxValue);        // 3.反序        Collections.sort(numList,ordering.reverse());        System.out.println("反序排列："+numList);        // 4.添加一个null值        numList.add(null);        System.out.println("添加null值后："+numList);        // 5.null存放在前、后        Collections.sort(numList,ordering.nullsFirst());        System.out.println("null在前："+numList);        Collections.sort(numList,ordering.nullsLast());        System.out.println("null在后："+numList);        System.out.println("===========================");        // 6.字符串null        List<String> names = new ArrayList<String>();        names.add("Ram");        names.add("Shyam");        names.add("Mohan");        names.add("Sohan");        names.add("Ramesh");        names.add("Suresh");        names.add("Naresh");        names.add("Mahesh");        names.add(null);        names.add("Vikas");        names.add("Deepak");        System.out.println("排序前："+names);        Collections.sort(names,ordering.nullsFirst().reverse());        System.out.println("排序后："+names);    }}

3. 输出：

排序前：[5, 30, 25, 10, 15]自然排序：[5, 10, 15, 25, 30]是否已排序：true最小值：5最大值：30反序排列：[30, 25, 15, 10, 5]添加null值后：[30, 25, 15, 10, 5, null]null在前：[null, 5, 10, 15, 25, 30]null在后：[5, 10, 15, 25, 30, null]===========================排序前：[Ram, Shyam, Mohan, Sohan, Ramesh, Suresh, Naresh, Mahesh, null, Vikas, Deepak]排序后：[Vikas, Suresh, Sohan, Shyam, Ramesh, Ram, Naresh, Mohan, Mahesh, Deepak, null]

附录：

参考：http://www.yiibai.com/guava/guava_ordering_class.html

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