Guava记录 - ComparisonChain

通常情况下，在日常工作中咱使用的比较方式有两种:

a、通过比较器比较
b、通过比较运算符比较

当我们比较对象的时候，guava官网也对此举例说明如下:

image.png

借助翻译软件，大致意思如下😄:

这段代码很容易出错，难以扫描错误，而且冗长得令人不快。我们应该能做得更好。

因此，在guava的集合包下提供了ComparisonChain类，支持引用类型以及Comparable比较，简单使用如下:

 public static void main(String[] args) {
        Integer numberLeft = 1;
        Integer numberRight = 2;
        System.out.println("=========测试左边小右边大========");
        System.out.println(ComparisonChain.start().compare(numberLeft, numberRight,Ordering.natural().nullsLast()).result());
        System.out.println("=========测试左边大右边小========");
        System.out.println(ComparisonChain.start().compare(numberRight, numberLeft).result());
        System.out.println("=========测试左右相等========");
        System.out.println(ComparisonChain.start().compare(numberRight, numberRight).result());

        System.out.println("=============compareFalseFirst==================");


        //注意参数不能为null,否则会出现npe
        Boolean booleanLeft = true;
        Boolean booleanRight = false;
        System.out.println("=========测试左边true右边false========");
        System.out.println(ComparisonChain.start().compareFalseFirst(booleanLeft, booleanRight).result());
        System.out.println("=========测试左边false右边true========");
        System.out.println(ComparisonChain.start().compareFalseFirst(booleanRight, booleanLeft).result());
        System.out.println("=========测试左右相等false========");
        System.out.println(ComparisonChain.start().compareFalseFirst(booleanRight, booleanRight).result());
        System.out.println("=========测试左右相等true========");
        System.out.println(ComparisonChain.start().compareFalseFirst(booleanLeft, booleanLeft).result());

        System.out.println("===============compareTrueFirst================");

        System.out.println("=========测试左边true右边false========");
        System.out.println(ComparisonChain.start().compareTrueFirst(booleanLeft, booleanRight).result());
        System.out.println("=========测试左边false右边true========");
        System.out.println(ComparisonChain.start().compareTrueFirst(booleanRight, booleanLeft).result());
        System.out.println("=========测试左右相等false========");
        System.out.println(ComparisonChain.start().compareTrueFirst(booleanRight, booleanRight).result());
        System.out.println("=========测试左右相等true========");
        System.out.println(ComparisonChain.start().compareTrueFirst(booleanLeft, booleanLeft).result());

        //多个compare的时候，result结果为第一个compare的结果
        System.out.println(ComparisonChain.start().compare(numberLeft, numberRight).compare(numberRight,numberLeft).result());

    }

执行结果如下:

image.png

......