Java文件操作之按行读取文件和遍历目录的方法

package test;  import java.io.*; import java.util.*;  public class ReadTest {    public static List<String> first_list;   public static List<String> second_list;    public ReadTest() {     first_list = new LinkedList<>();     second_list = new LinkedList<>();   }    public static void ReadFile() {     final String filename = "d://aa.txt";     String str = null;     int i = 0;     try {       LineNumberReader reader = null;       reader = new LineNumberReader(new FileReader(filename));       while ((str = reader.readLine()) != null) {         if (!str.isEmpty()) {           String values[] = str.split("  ");           first_list.add(values[0]);           second_list.add(values[1]);         }       }     } catch (IOException e) {       e.printStackTrace();     }   }    public static void main(String args[]) {      ReadTest reader = new ReadTest();     reader.ReadFile();      for (int i = 0; i < first_list.size(); i++) {       System.out.println(first_list.get(i) + ":" + second_list.get(i));     }   } } 

class ListFiles{   public static ArrayList filelist = new ArrayList();      public static void listfiles(String dir){       File file = new File(dir);     File[] files = file.listFiles();     if(null == files){       return;     }     for(int i = 0; i < files.length; i++){       if(files[i].isDirectory())       {         listfiles(files[i].getAbsolutePath());       }       else{         System.out.println(files[i]);         filelist.add(files[i]);       }     }   } } 

//非递归  public static void scanDirNoRecursion(String path){   LinkedList list = new LinkedList();    File dir = new File(path);    File file[] = dir.listFiles();    for (int i = 0; i < file.length; i++) {      if (file[i].isDirectory())        list.add(file[i]);      else{        System.out.println(file[i].getAbsolutePath());        num++;      }    }    File tmp;    while (!list.isEmpty()) {      tmp = (File)list.removeFirst();//首个目录      if (tmp.isDirectory()) {        file = tmp.listFiles();         if (file == null)          continue;        for (int i = 0; i < file.length; i++) {          if (file[i].isDirectory())            list.add(file[i]);//目录则加入目录列表，关键          else{            System.out.println(file[i]);            num++;          }        }      } else {        System.out.println(tmp);        num++;      }    }  }

import java.io.File;import java.util.LinkedList;public class FileSystem {  public static int num;   public static void main(String[] args) {        long a = System.currentTimeMillis();    //String path="c:";    num=0;    String[] lists={"c:","d:"};    /*    for(int i=0;i<lists.length;i++){     File file=new File(lists[i]);     scanDirRecursion(file);    */    for(int i=0;i<lists.length;i++){      scanDirNoRecursion(lists[i]);    }        System.out.print("文件总数:"+num);    System.out.print("总耗时:");    System.out.println(System.currentTimeMillis() - a);  }