java ArrayList排序不区分大小写

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最近在做代码勇士codewars的题目，顺便记录一下自己的解决方案。

1.排序类

1.1 不使用预定义比较器

package com.dylan.practice;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;/** * 不区分大小写的升序排序List * @author xusucheng * @create 2017-11-23 **/public class Sorter {    public static List<String> sort(List<String> textbooks) {        Collections.sort(textbooks, new Comparator<String>(){            public int compare(String s1, String s2) {                return s1.toUpperCase().compareTo(s2.toUpperCase());            }        });        return textbooks;    }    public static void main(String[] args) {        List<String> unsort = new ArrayList<String>();        for (String s : new String[]{"Algebra", "History", "Geometry", "english"}) {            unsort.add(s);        }        System.out.println(sort(unsort));    }    //自定义比较类    /*static class SortCaseNoSensitive implements Comparator<String>{        public int compare(String s1, String s2) {            return s1.toUpperCase().compareTo(s2.toUpperCase());        }    }*/}

1.2 使用预定义比较器

import java.util.ArrayList;import java.util.Collections;class Sorter {  public static ArrayList<String> sort(ArrayList<String> textbooks) {    Collections.sort(textbooks, String.CASE_INSENSITIVE_ORDER);    System.out.println(textbooks);    return textbooks;  }}

2.测试类

/** * @author xusucheng * @create 2017-11-24 **/import com.dylan.practice.Sorter;import org.junit.Test;import static org.junit.Assert.assertEquals;import org.junit.runners.JUnit4;import java.util.ArrayList;import java.util.Collections;import java.lang.Math;public class SortingTest {    @Test    public void basicTest() {        ArrayList<String> sorted = new ArrayList<String>();        ArrayList<String> strs = new ArrayList<String>();        for(String s : new String[] {"Algebra", "History", "Geometry", "English"})            strs.add(s);        for(String s : new String[] {"Algebra", "English", "Geometry", "History"})            sorted.add(s);        assertEquals(sorted, Sorter.sort(strs));    }    @Test    public void capitalizationTest() {        ArrayList<String> sorted = new ArrayList<String>();        ArrayList<String> strs = new ArrayList<String>();        for(String s : new String[] {"Algebra", "history", "Geometry", "english"})            strs.add(s);        for(String s : new String[] {"Algebra", "english", "Geometry", "history"})            sorted.add(s);        assertEquals(sorted, Sorter.sort(strs));    }    @Test    public void symbolsTest() {        ArrayList<String> sorted = new ArrayList<String>();        ArrayList<String> strs = new ArrayList<String>();        for(String s : new String[] {"Alg#bra", "$istory", "Geom^try", "**English"})            strs.add(s);        for(String s : new String[] {"$istory", "**English", "Alg#bra", "Geom^try"})            sorted.add(s);        assertEquals(sorted, Sorter.sort(strs));    }}

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