使用Java数组列表按大小对目录中的文件进行排序

问题描述

该目录有n个文件.我正在创建类，它将使用java arraylist从目录中按大小对文件进行排序.

The directory has n number of files.I am creating class, it will sort files by size from directory using java arraylist.

我可以读取文件名和大小.但是如何按大小对文件排序?

I can read the file name and size. but how to sort the files by size?

    import java.io.File;
    import java.io.FilenameFilter;
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Collections;
    import java.util.Comparator;

    public class SortingFiles
    {
        public static void main(String[] args)
        {
            File dir=null;
            File[] paths;

            final ArrayList<String> al= new ArrayList<String>();


            try{
                // create new file object
                dir = new File("D:\\New folder\\New");

                // array of files and directory
                paths = dir.listFiles();


                ArrayList<File> fileList = new ArrayList<File>();


                for(File file:paths)
                {
                    // prints filename and directory name
                    System.out.println(file.getName()+" - " +file.length() );


                    al.add(file.getName());
}


        }
        catch(Exception e)
        {
                        e.printStackTrace();
        }
    }

---

我试图按大小对文件进行排序

---

i have tried to sort the file by size

 for(int i=1; i<al.size(); i++)
 {
         System.out.println("\n  Aftr : " +al.get(i) );
  }

但是它不起作用..任何人都可以帮助我..我正在尝试不使用"import org.apache.commons.io.FileUtils;".那该怎么办?

But it is not working.. Any one can help me..I am trying without "import org.apache.commons.io.FileUtils;". So what to do ?

推荐答案

您必须创建一个 Map< String，Long> 并使用 filename 注册每个文件作为键，文件大小作为值.最后，使用自然顺序，按值对 Map 进行排序，例如:

You have to create a Map<String, Long> and register each file by using the filename as key and the filesize as value.Finally, sort the Map by value using natural order, e.g:

List<Path> paths = Files.walk(Paths.get(folder))
  .filter(Files::isRegularFile)
  .sorted((Path a, Path b) -> a.toFile().length() > b.toFile().length() ? 1 : -1)
  .collect(Collectors.toList());

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