JAVA新特性（5）Comparator

最新推荐文章于 2025-04-01 22:11:23 发布

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最新推荐文章于 2025-04-01 22:11:23 发布

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分类专栏： Java总结

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本文介绍了Java 1.8中Comparator接口的重要变化，它被转换为函数式接口，并提供了新的静态与默认方法，增强了比较器的功能和使用灵活性。

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Comparator接口：JDK1.8中改为函数式接口，提供 : int compare(T o1, T o2); 抽象方法
1.8中Comparator接口提供了一些static方法和default方法。

    @Test
    public void Test1(){
        List<String> list = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list1 = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list2 = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list3 = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list4 = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list5 = Arrays.asList("nihao","hello","Hi","Women");
        List<String> list6 = Arrays.asList("nihao","hello","Hi","Women");

        //字符串长度排序
        Collections.sort(list,(l1,l2)->l1.length()-l2.length());
        Collections.sort(list1, Comparator.comparingInt(String::length).reversed());
        //此reversed()情况下Comparator.comparingInt中对参数无法进行类型推断需要; (String i)
        Collections.sort(list2, Comparator.comparingInt((String i)->i.length()).reversed());
        list3.sort(Comparator.comparingInt(String::length));

        //先字符串长度，长度相同的再字母顺序
        Collections.sort(list4,Comparator.comparingInt(String::length).
                thenComparing(String.CASE_INSENSITIVE_ORDER));
        //与上一种等价
//        Collections.sort(list4,Comparator.comparingInt(String::length).
//                thenComparing((i1,i2)->i1.toUpperCase().compareTo(i2.toUpperCase())));

        System.out.println(list);
        System.out.println(list1);
        System.out.println(list2);
        System.out.println(list3);
        System.out.println(list4);
    }