排序2的ArrayList同时

问题描述

说我有两个的ArrayList

Say I have two ArrayLists:

name: [Four, Three, One, Two]
num:  [4, 3, 1, 2]

如果我做的：Arrays.sort（NUM），那么我有：

If I do: Arrays.sort(num), then I have:

name: [Four, Three, One, Two]
num:  [1, 2, 3, 4]

有什么办法我能做上的num排序，并把它体现在名称为好，这样我可能会结束：

Is there any way I can possibly do a sort on num and have it reflected in name as well, so that I might end up with:

name: [One, Two, Three, Four]
num:  [1, 2, 3, 4]

？请你帮助我。我想比较器和对象，但几乎不知道他们。

? Please do help me out. I thought of Comparators and Objects, but barely know them at all.

推荐答案

您应该以某种方式的关联 名称和 NUM 字段为一类，然后有一个特定的类的实例的列表。在这个类中，提供了一个的compareTo（）方法，它会检查的数值。如果您的实例进行排序，然后名称字段将成为你的愿望，以及顺序。

You should somehow associate name and num fields into one class and then have a list of instances of that specific class. In this class, provide a compareTo() method which checks on the numerical values. If you sort the instances, then the name fields will be in the order you desire as well.

class Entity implements Comparable<Entity> {
    String name;
    int num;
    Entity(String name, int num) {
        this.name = name;
        this.num = num;
    }
    @Override
    public int compareTo(Entity o) {
        if (this.num > o.num)
            return 1;
        else if (this.num < o.num)
            return -1;
        return 0;
    }
}

测试code可能是这样的：

Test code could be like this:

public static void main(String[] args) {
    List<Entity> entities = new ArrayList<Entity>();
    entities.add(new Entity("One", 1));
    entities.add(new Entity("Two", 2));
    entities.add(new Entity("Three", 3));
    entities.add(new Entity("Four", 4));
    Collections.sort(entities);

    for (Entity entity : entities)
        System.out.print(entity.num + " => " + entity.name + " ");
}

输出：

1 =>扰2 =>两个3 =>三4 =>四

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