java - Scala 在非常长的字符串上调用 length() 会引发异常 : Maximum String literal length exceeded

Question

我为 HackerRank BigSorting 写了一个 Scala 解决方案, 并在某些测试用例中得到 RuntimeException。我测试了 scastie 中的输入, 似乎问题是由在一个很长的字符串上调用 length() 引起的，但同样是 java solution没有问题，这是一个错误吗？ 我的解决方案代码是:

object Solution {
    def stringSort(x:String, y:String):Boolean = {
        var result = true

        if(x.length < y.length){
            result = true
        }else if(x.length > y.length){
            result = false
        }else{
            var founded = false
            var i = 0
            while(i < x.length && !founded){
                var xi = x.charAt(i)
                var yi = y.charAt(i)
                if(xi != yi){
                    result = xi < yi
                    founded = true
                }
                i += 1
            }
        }
        result
    }

    def bigSort(unsorted:Array[String]):Array[String] = {
        return unsorted.sortWith(stringSort)
    }

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        var n = sc.nextInt();
        var unsorted = new Array[String](n);
        for(unsorted_i <- 0 to n-1) {
           unsorted(unsorted_i) = sc.next();
        }
        print(bigSort(unsorted).mkString("\n"))
        // your code goes here
    }
}

异常(exception)是

java.lang.IllegalArgumentException: Maximum String literal length exceeded
    at scala.tools.asm.ByteVector.putUTF8(ByteVector.java:213)
    at scala.tools.asm.ClassWriter.newUTF8(ClassWriter.java:1114)
    at scala.tools.asm.ClassWriter.newString(ClassWriter.java:1582)
    at scala.tools.asm.ClassWriter.newConstItem(ClassWriter.java:1064)
    at scala.tools.asm.MethodWriter.visitLdcInsn(MethodWriter.java:1187)
    at scala.tools.asm.tree.LdcInsnNode.accept(LdcInsnNode.java:71)
    at scala.tools.asm.tree.InsnList.accept(InsnList.java:162)
    at scala.tools.asm.tree.MethodNode.accept(MethodNode.java:820)
    at scala.tools.asm.tree.MethodNode.accept(MethodNode.java:730)
    at scala.tools.asm.tree.ClassNode.accept(ClassNode.java:412)
...

Java 解决方案

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String[] unsorted = new String[n];
        for(int i = 0; i < n; i++) unsorted[i] = in.next();

        Arrays.sort(unsorted,new Comparator<String>() {
            @Override
            public int compare(String a, String b) 
            {
                return StringAsIntegerCompare(a,b);
            }
        });

        StringBuilder output = new StringBuilder("");
        for(String num : unsorted)
            output.append(num+"\n");
        System.out.println(output);
    }

    static int StringAsIntegerCompare(String s1, String s2)
    {
        if(s1.length() > s2.length()) return 1;
        if(s1.length() < s2.length()) return -1;
        for(int i = 0; i < s1.length(); i++)
        {
            if((int)s1.charAt(i) > (int)s2.charAt(i)) return 1;
            if((int)s1.charAt(i) < (int)s2.charAt(i)) return -1;
        }
        return 0;
    }
}

Answer 1

我能看到的 Java 和 Scala 代码之间唯一的实质性区别是 Scala sortWith 创建一个新数组，这与 Arrays.sort 不同(并且可能有一些中间开销太)，所以你可能会耗尽内存。你可以试试

import scala.math.Ordering
import scala.util.Sorting

val byLength: Ordering[String] = ... // your implementation, similar to Java comparator

Sorting.quickSort(unordered)(byLength) // instead of sortWith, sorts in-place

参见 http://www.scala-lang.org/api/2.12.0/scala/math/Ordering.html和 http://www.scala-lang.org/api/2.12.0/scala/util/Sorting $.html 用于相关文档。