package com;


import java.io.File;

/**
 *
 * @author ?Mukesh
 */
public class ListFiles {

     static File mainFolder = new File("D:\\Movies");

     public static void main(String[] args)
     {
         ListFiles lf = new ListFiles();
         lf.getFiles(lf.mainFolder);

         long fileSize = mainFolder.length();
             System.out.println("mainFolder size in bytes is: " + fileSize);
             System.out.println("File size in KB is : " + (double)fileSize/1024);
             System.out.println("File size in MB is :" + (double)fileSize/(1024*1024));
     }
     public void getFiles(File f){
         File files[];
         if(f.isFile())
             System.out.println(f.getAbsolutePath());
         else{
             files = f.listFiles();
             for (int i = 0; i < files.length; i++) {
                 getFiles(files[i]);
             }
         }
     }
}

这将很好地工作:

private static void addfiles(File inputValVal, ArrayList<File> files)
{
  if(inputVal.isDirectory())
  {
    ArrayList <File> path = new ArrayList<File>(Arrays.asList(inputVal.listFiles()));

    for(int i=0; i<path.size(); ++i)
    {
        if(path.get(i).isDirectory())
        {
            addfiles(path.get(i),files);
        }
        if(path.get(i).isFile())
        {
            files.add(path.get(i));
        }
     }

    /*  Optional : if you need to have the counts of all the folders and files you can create 2 global arrays 
        and store the results of the above 2 if loops inside these arrays */
   }

   if(inputVal.isFile())
   {
     files.add(inputVal);
   }

}

File folder = new File("/Users/you/folder/");
File[] listOfFiles = folder.listFiles();

for (File file : listOfFiles) {
    if (file.isFile()) {
        System.out.println(file.getName());
    }
}

给定一个baseDir，列出它下面的所有文件和目录，迭代编写。

    public static List<File> listLocalFilesAndDirsAllLevels(File baseDir) {

    List<File>  collectedFilesAndDirs   = new ArrayList<>();
    Deque<File> remainingDirs           = new ArrayDeque<>();

    if(baseDir.exists()) {
        remainingDirs.add(baseDir);

        while(!remainingDirs.isEmpty()) {
            File dir = remainingDirs.removeLast();
            List<File> filesInDir = Arrays.asList(dir.listFiles());
            for(File fileOrDir : filesInDir)  {
                collectedFilesAndDirs.add(fileOrDir);
                if(fileOrDir.isDirectory()) {
                    remainingDirs.add(fileOrDir);
                }
            }
        }
    }

    return collectedFilesAndDirs;
}

java.io.FileFilter的用法很好，见https://stackoverflow.com/a/286001/146745

File fl = new File(dir);
File[] files = fl.listFiles(new FileFilter() {          
    public boolean accept(File file) {
        return file.isFile();
    }
});

防止listFiles()函数的nullpointerexception，并递归地从子目录中获取所有文件。

 public void listFilesForFolder(final File folder,List<File> fileList) {
    File[] filesInFolder = folder.listFiles();
    if (filesInFolder != null) {
        for (final File fileEntry : filesInFolder) {
            if (fileEntry.isDirectory()) {
            listFilesForFolder(fileEntry,fileList);
        } else {
            fileList.add(fileEntry);
        }
     }
    }
 }

 List<File> fileList = new List<File>();
 final File folder = new File("/home/you/Desktop");
 listFilesForFolder(folder);