在 arrayList 中对对象的 double 值进行排序 [英] Sorting a double value of an object within an arrayList

问题描述

我正在尝试根据他们的双精度分数属性值对我的自定义类染色体进行排序.这些染色体存储在一个 ArrayList 中.我知道我必须使用比较器，但在过去的一个小时里我在网上阅读了很多不同的意见，我完全糊涂了.

I'm trying to sort my custom class chromosome by the value of their score attribute which is a double. These chromosomes are stored within an ArrayList. I know I have to use a comparator but I've read so many differing opinions online in the last hour that I'm utterly confused.

附上我的代码，如果有人能指出我正确的方向，我将不胜感激.

Attached is my code, if someone could point me in the right direction I would be much appreciated.

public class Chromosome
{

    public Gene[] genes;
    public double score;

    public Chromosome(int l)
    {
        genes = new Gene[l]; 
    }

    public int getLength()
    {
        return genes.length;
    }

    public void printChromo()
    {
        for(int i=0;i<this.genes.length;i++)
        {
            System.out.println(""+this.genes[i].teacher+","+
                this.genes[i].lecture+","+
                this.genes[i].room+","+
                this.genes[i].time+"");
        }   
    }

    public void setScore(double score)
    {
        this.score=score;
    }

    public double getScore()
    {
        return this.score;
    }
}

不知道这有什么不同，但分数只能是 0.0 到 1.0 之间的两倍

Don't know this make a difference but the score can only be a double between and including 0.0 to 1.0

推荐答案

使用 比较器:

Collections.sort(myList, new Comparator<Chromosome>() {
    @Override
    public int compare(Chromosome c1, Chromosome c2) {
        return Double.compare(c1.getScore(), c2.getScore());
    }
});

如果您计划以这种方式对大量 List 进行排序，我建议让 Chromosome 实现 Comparable 接口(在这种情况下，您可以简单地调用 Collections.sort(myList)，无需指定显式的 Comparator).

If you plan on sorting numerous Lists in this way I would suggest having Chromosome implement the Comparable interface (in which case you could simply call Collections.sort(myList), without the need of specifying an explicit Comparator).

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