使用Lambda表达式对多个属性进行排序 [英] Sorting multiple attribute with Lambda Expressions

问题描述

这是我的清单：

Name: Ben     || Age: 5 || Group: 1
Name: Andy    || Age: 6 || Group: 2
Name: Charlie || Age: 6 || Group: 2
Name: Ben     || Age: 5 || Group: 1
Name: Andy    || Age: 5 || Group: 2
Name: Charlie || Age: 5 || Group: 1

我想按组，如果组等于年龄，如果年龄等于名称。但到目前为止，我只能使用Lambda表达式按一个属性排序：

I want to sort the list by Group, if Group is equal then by Age, and if Age is equal then by Name. But so far I can only sort by one attribute, using Lambda Expressions:

list.sort((Object o1, Object o2) -> o1.getGroup().compareTo(o2.getGroup()));

如果我尝试

o1.getGroup().compareTo(o2.getGroup()) && o1.getAge().compareTo(o2.getAge())

结果发现错误...

推荐答案

将lambda 表达式更改为lambda {block} ，然后你不必指定参数类型：

Change lambda expression to lambda {block}, and you don't have to specify the parameter types:

list.sort((o1, o2) -> {
    int cmp = o1.getGroup().compareTo(o2.getGroup());
    if (cmp == 0)
        cmp = Integer.compare(o1.getAge(), o2.getAge());
    if (cmp == 0)
        cmp = o1.getName().compareTo(o2.getName());
    return cmp;
});

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