尝试在Java中使用自定义比较器时出错

Question

I am trying to create a class that reads a text file with each line having the same format, "#order) score - Name". I want to be able to read each line from a file and store it in an array, and then sort it by the highest score. I was able to accomplish this when it was just "#order) score", but adding the string to the mixture has complicated things. The error is

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>)

The text file is:

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

and the class is:

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();


    }
}

Any feedback is greatly appreciated!

Answer 1

Arrays.sort is expecting T[] but you are providing ArrayList which is not array, it is a list which is using array internally to hold elements.

Use Collections.sort instead, or since Java 8 you can use yourList.sort(comparator) .

---

BTW split method is using regular expression (regex) as argument where ) is one of regex special characters . If you want to treat ) as literal you need to escape it (more info at Escape ( in regular expression )

So instead of aScore.split(") "); you can use aScore.split("\\\\) ");