这将读取指定路径下的指定文件扩展名文件(也可以查看子文件夹)

public static Map<String,List<File>> getFileNames(String 
dirName,Map<String,List<File>> filesContainer,final String fileExt){
    String dirPath = dirName;
    List<File>files = new ArrayList<>();
    Map<String,List<File>> completeFiles = filesContainer; 
    if(completeFiles == null) {
        completeFiles = new HashMap<>();
    }
    File file = new File(dirName);

    FileFilter fileFilter = new FileFilter() {
        @Override
        public boolean accept(File file) {
            boolean acceptFile = false;
            if(file.isDirectory()) {
                acceptFile = true;
            }else if (file.getName().toLowerCase().endsWith(fileExt))
              {
                acceptFile = true;
              }
            return acceptFile;
        }
    };
    for(File dirfile : file.listFiles(fileFilter)) {
        if(dirfile.isFile() && 
dirfile.getName().toLowerCase().endsWith(fileExt)) {
            files.add(dirfile);
        }else if(dirfile.isDirectory()) {
            if(!files.isEmpty()) {
                completeFiles.put(dirPath, files);  
            }

getFileNames(dirfile.getAbsolutePath(),completeFiles,fileExt);
        }
    }
    if(!files.isEmpty()) {
        completeFiles.put(dirPath, files);  
    }
    return completeFiles;
}

private static final String ROOT_FILE_PATH="/";
File f=new File(ROOT_FILE_PATH);
File[] allSubFiles=f.listFiles();
for (File file : allSubFiles) {
    if(file.isDirectory())
    {
        System.out.println(file.getAbsolutePath()+" is directory");
        //Steps for directory
    }
    else
    {
        System.out.println(file.getAbsolutePath()+" is file");
        //steps for files
    }
}

只需使用“文件”遍历所有“文件”。walkFileTree (java7)

Files.walkFileTree(Paths.get(dir), new SimpleFileVisitor<Path>() {
    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
        System.out.println("file: " + file);
        return FileVisitResult.CONTINUE;
    }
});

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

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

void getFiles(){
        String dirPath = "E:/folder_name";
        File dir = new File(dirPath);
        String[] files = dir.list();
        if (files.length == 0) {
            System.out.println("The directory is empty");
        } else {
            for (String aFile : files) {
                System.out.println(aFile);
            }
        }
    }

我认为这是读取文件夹和子文件夹中的所有文件的好方法

private static void addfiles (File input,ArrayList<File> files)
{
    if(input.isDirectory())
    {
        ArrayList <File> path = new ArrayList<File>(Arrays.asList(input.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));
            }
        }
    }
    if(input.isFile())
    {
        files.add(input);
    }
}