爪哇 - 从文件字符串属性排序的ArrayList [英] Java - Sorting ArrayList by string attribute from file

问题描述

这是我一直在努力实现的不亦乐乎。我现在有这对我的getter和setter方法​​的对象属性的类。我有另一个类，我读我的CSV文件，然后把它放在一个ArrayList中。该文件的每一行是一个对象，每一列是一个我已经分配了一个属性，这个工程的时候我做的System.out.println。

Here is what I have been trying to achieve the whole day. I currently have a class which has the attributes for my objects with setters and getters. I have another class where I read my CSV file and put it in a ArrayList. Every row of the file is a object and every column is a attribute which I have assigned and this works when I do a System.out.println.

我现在想的就是创建一个类，它可以由一个字符串的属性的对象进行排序。我如何去这样做，因为我一直在尝试使用比较所有的一天，但我不知道我在做什么。

What I now want to is create a class that can sort the objects by an attribute which is a string. How do I go about to do this as I have been trying all day using Comparators but I have no idea what I am doing.

推荐答案

比方说你有一个CSV文件是这样的：

Lets say you have a CSV file like this:

John,Smith,28
Jane,Doe,37

等等，然后我们有一个类Person ，是这样的：

public class Person {
    private String firstName;
    private String lastName;
    private int age;

    //getters and setters

   //equals and hashCode
}

我们再读取该文件，一行行，成列表与LT;人＆GT; 。现在，我们希望通过的lastName 到列表排序。这可以像这样做：

We then read the file, line by line, into a List<Person>. We now want to sort the List by lastName. This can be done like so:

final List<Person> people = readFile();
people.sort(Comparator.comparing(Person::getLastName));

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