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);
            }
         }
        }
     }


}

import java.io.File;


public class ReadFilesFromFolder {
  public static File folder = new File("C:/Documents and Settings/My Documents/Downloads");
  static String temp = "";

  public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println("Reading files under the folder "+ folder.getAbsolutePath());
    listFilesForFolder(folder);
  }

  public static void listFilesForFolder(final File folder) {

    for (final File fileEntry : folder.listFiles()) {
      if (fileEntry.isDirectory()) {
        // System.out.println("Reading files under the folder "+folder.getAbsolutePath());
        listFilesForFolder(fileEntry);
      } else {
        if (fileEntry.isFile()) {
          temp = fileEntry.getName();
          if ((temp.substring(temp.lastIndexOf('.') + 1, temp.length()).toLowerCase()).equals("txt"))
            System.out.println("File= " + folder.getAbsolutePath()+ "\\" + fileEntry.getName());
        }

      }
    }
  }
}

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";
       }
}

使用Java 1.7来递归列出命令行指定目录中的文件的简单示例:

import java.io.File;

public class List {
    public static void main(String[] args) {
        for (String f : args) {
            listDir(f);
        }
    }

    private static void listDir(String dir) {
        File f = new File(dir);
        File[] list = f.listFiles();

        if (list == null) {
            return;
        }

        for (File entry : list) {
            System.out.println(entry.getName());
            if (entry.isDirectory()) {
                listDir(entry.getAbsolutePath());
            }
        }
    }
}

package com.commandline.folder;

import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

public class FolderReadingDemo {
    public static void main(String[] args) {
        String str = args[0];
        final File folder = new File(str);
//      listFilesForFolder(folder);
        listFilesForFolder(str);
    }

    public static void listFilesForFolder(String str) {
        try (Stream<Path> paths = Files.walk(Paths.get(str))) {
            paths.filter(Files::isRegularFile).forEach(System.out::println);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void listFilesForFolder(final File folder) {
        for (final File fileEntry : folder.listFiles()) {
            if (fileEntry.isDirectory()) {
                listFilesForFolder(fileEntry);
            } else {
                System.out.println(fileEntry.getName());
            }
        }
    }

}

一个注释根据获得目录中的所有文件。 方法files .walk(path)将通过遍历以给定起始文件为根的文件树来返回所有文件。

例如，下面有一个文件树:

\---folder
    |   file1.txt
    |   file2.txt
    |
    \---subfolder
            file3.txt
            file4.txt

使用java.nio.file.Files.walk(路径):

Files.walk(Paths.get("folder"))
        .filter(Files::isRegularFile)
        .forEach(System.out::println);

给出如下结果:

folder\file1.txt
folder\file2.txt
folder\subfolder\file3.txt
folder\subfolder\file4.txt

要获取当前目录下的所有文件，请使用java.nio.file.Files.list(Path):

Files.list(Paths.get("folder"))
        .filter(Files::isRegularFile)
        .forEach(System.out::println);

结果:

folder\file1.txt
folder\file2.txt