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();
    }
});

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class AvoidNullExp {

public static void main(String[] args) {

    List<File> fileList =new ArrayList<>();
     final File folder = new File("g:/master");
     new AvoidNullExp().listFilesForFolder(folder, fileList);
}

    public void listFilesForFolder(final File folder,List<File> fileList) {
        File[] filesInFolder = folder.listFiles();
        if (filesInFolder != null) {
            for (final File fileEntry : filesInFolder) {
                if (fileEntry.isDirectory()) {
                    System.out.println("DIR : "+fileEntry.getName());
                listFilesForFolder(fileEntry,fileList);
            } else {
                System.out.println("FILE : "+fileEntry.getName());
                fileList.add(fileEntry);
            }
         }
        }
     }


}

File directory = new File("/user/folder");      
File[] myarray;  
myarray=new File[10];
myarray=directory.listFiles();
for (int j = 0; j < myarray.length; j++)
{
       File path=myarray[j];
       FileReader fr = new FileReader(path);
       BufferedReader br = new BufferedReader(fr);
       String s = "";
       while (br.ready()) {
          s += br.readLine() + "\n";
       }
}

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);
   }

}

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);
            }
        }
    }

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;
    }
});