如何使用 Collection.sort() 对 FastUtil BigList 进行排序

Question

如果我有 arraylist 我可以使用 Collection.sort() 这是非常有效和快速的。但是现在我必须使用 BigList 来保存我的对象类型的许多元素，并且我必须按值对它们进行排序，从名为 JasPlayer 的对象杀死为 int，昵称为 String。

我尝试使用 Collection.sort() 最好的方法来做到这一点，但我不能像普通列表那样使用它。

private BigList<JasPlayer> playerRankingPlaces;

public BigList<JasPlayer> getRanking() {

    return this.playerRankingPlaces;

}

public void addRankingElement(JasPlayer element) {

    this.playerRankingPlaces.add(element);

}

public void setRanking(BigList<JasPlayer> playerRanking) {

    this.playerRankingPlaces = playerRanking;

}

public void sortRankingList() {

    for(JasPlayer player : JasPlayerUtils.getPlayers()) {

        addRankingElement(player);

        long startTime = System.nanoTime();

           //THERE's Problem, i can't use biglist like normal list :\

        Collections.sort(playerRankingPlaces, Comparator.comparing(Ranking :: getKills).thenComparing(Ranking :: getName));

        long endTime = System.nanoTime() - startTime;

        MessageUtils.sendDebug("Sorting " + playerRankingPlaces.size() + "took " +  endTime / 1e9 + " seconds");

    }

}

private static int getKills(UUID uuid) {

    if(JasPlayerUtils.findByUUID(uuid).isPresent()) {

        return JasPlayerUtils.findByUUID(uuid).get().getKills();

    }

    return 0;

}

private static String getName(UUID uuid) {

    if(JasPlayerUtils.findByUUID(uuid).isPresent()) {

        return JasPlayerUtils.findByUUID(uuid).get().getPlayer().getName();

    }

    return "Brak";

}

Answer 1

我很确定您正遭受XY 问题的困扰。Fastutil 的 BigList 比普通列表更难使用，如果元素数量不能超过 Integer.MAX_VALUE，则没有理由使用它。如果你真的需要它（假设你真的有 30 亿个元素并且需要将它们作为列表存储在内存中），我发现对 BigList 进行排序的方式是使用 BigArrays 类中的静态排序方法mergesort 和 quicksort。他们将其作为论据：要排序的开始（包括）和结束（不包括）索引，即 0 和列表的大小一个 LongComparator ，它是一个给定两个长索引的对象，比较这些索引处的元素BigSwapper，它是一个给定两个长索引的对象，交换这些索引处的元素。例子：import it.unimi.dsi.fastutil.BigArrays;import it.unimi.dsi.fastutil.BigList;import it.unimi.dsi.fastutil.BigSwapper;import it.unimi.dsi.fastutil.longs.LongComparator;import it.unimi.dsi.fastutil.objects.ObjectBigArrayBigList;public class App&nbsp;{&nbsp; &nbsp; public static void main( String[] args )&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; BigList<String> bigList = new ObjectBigArrayBigList<String>();&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("Z");&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("X");&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("Y");&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("A");&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("C");&nbsp; &nbsp; &nbsp; &nbsp; bigList.add("B");&nbsp; &nbsp; &nbsp; &nbsp; System.out.println("Biglist before: " + bigList.toString());&nbsp; &nbsp; &nbsp; &nbsp; LongComparator cmp = (i,j) -> bigList.get(i).compareTo(bigList.get(j));&nbsp; &nbsp; &nbsp; &nbsp; BigSwapper swapper = (i,j) -> {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; String tmp = bigList.get(i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; bigList.set(i, bigList.get(j));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; bigList.set(j, tmp);&nbsp; &nbsp; &nbsp; &nbsp; };&nbsp; &nbsp; &nbsp; &nbsp; BigArrays.mergeSort(0, bigList.size64(), cmp, swapper);&nbsp; &nbsp; &nbsp; &nbsp; System.out.println("Biglist after : " + bigList.toString());&nbsp; &nbsp; &nbsp;}}输出：Biglist before: [Z, X, Y, A, C, B]Biglist after : [A, B, C, X, Y, Z]