尝试在 Java 中使用自定义比较器时出错

Question

我正在尝试创建一个 class 来读取文本文件，其中每一行都具有相同的格式，“#order) score - Name”。我希望能够从文件中读取每一行并将其存储在一个数组中，然后按最高分排序。当它只是“#order) score”时，我能够做到这一点，但是将字符串添加到混合物中会使事情变得复杂。错误是

Scoring.java:46: error: no suitable method found for sort(ArrayList<String>,<anonymous Comparator<String>>)
            Arrays.sort(scores, new Comparator<String>(){
                  ^
method Arrays.<T#1>sort(T#1[],Comparator<? super T#1>) is not applicable
  (cannot infer type-variable(s) T#1
    (argument mismatch; ArrayList<String> cannot be converted to T#1[]))
method Arrays.<T#2>sort(T#2[],int,int,Comparator<? super T#2>) is not applicable
  (cannot infer type-variable(s) T#2
    (actual and formal argument lists differ in length))
where T#1,T#2 are type-variables:
T#1 extends Object declared in method <T#1>sort(T#1[],Comparator<? super T#1>)
T#2 extends Object declared in method <T#2>sort(T#2[],int,int,Comparator<? super T#2>)

文本文件是：

1) 10000 - Michael
2) 10000 - Jake
3) 10000 - Alex

而 class 是：

import java.io.*;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Comparator;
public class Scoring
{ 
    private ArrayList<String> scores = new ArrayList<String>();
    public Scoring()
    {
        this(-1, "-1");
    }
    public Scoring(int newScore, String newName)
    {
        String highScoreFile = "scores.txt";
        String line;

        BufferedReader reader = null;
        try
        {
            File file = new File(highScoreFile);
            reader = new BufferedReader(new FileReader(file));
        }
        catch (FileNotFoundException fnfe)
        {
            fnfe.printStackTrace();
        }

        finally
        {
            try
            {

                while ((line = reader.readLine()) != null)
                {
                    String aScore = line;
                    String segments[] = aScore.split(") ");
                    aScore = segments[segments.length - 1];
                    scores.add(aScore);
                }
                if (newScore != -1 && !newName.equals("-1"));
                {
                    scores.add(newScore + " - " + newName);
                }
                System.out.println(Arrays.toString(scores.toArray()));
                Arrays.sort(scores, new Comparator<String>(){
                    @Override
                    public int compare(String o1, String o2)
                    {
                        return Integer.valueOf(o1).compareTo(Integer.valueOf(o2));
                    }
                });

                BufferedWriter writer = null;
                try
                {
                    File file = new File(highScoreFile);
                    FileWriter fw = new FileWriter(file);
                    writer = new BufferedWriter(fw);

                }
                catch (FileNotFoundException fnfe)
                {
                    fnfe.printStackTrace();
                }
                for (int i = 0; i < scores.size(); i++)
                {
                    writer.write((i + 1) + ") ");
                    writer.write(scores.get(i) + "\n");
                }
                System.out.println(Arrays.toString(scores.toArray()));
                reader.close();
                writer.close();
            }
            catch(IOException ioe)
            {
                ioe.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        Scoring score = new Scoring();


    }
}

非常感谢任何反馈！

Answer 1

Arrays.sort 期望 T[] 但您提供的 ArrayList 不是数组，它是一个在内部使用数组来保存元素的列表。

改用Collections.sort，或者因为Java 8 你可以使用yourList.sort(comparator).

BTW split 方法使用正则表达式 (regex) 作为参数，其中 ) 是正则表达式 special characters. If you want to treat ) as literal you need to escape it (more info at Escape ( in regular expression)

之一

所以您可以使用 aScore.split("\) ");

而不是 aScore.split(") ");

尝试在 Java 中使用自定义比较器时出错

Error when attempting to use custom comparator in Java

java

file-io

arraylist

comparator