package src;
 
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
 import java.io.IOException;
 
 public class Test {
 
   public static void main(String[] args) {
     File f = new File("src\test.txt");//文件在src名为test.txt中
     try {
       FileReader fr = new FileReader(f);//将文件读取到内容中
       int m;
       while((m=fr.read())!=-){
         System.out.print((char)(m));
       }
     } catch (FileNotFoundException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     } catch (IOException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     }
   }
 }

 package src;
 
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 
 public class Test {
 
   public static void main(String[] args) {
     File f = new File("src\fin.txt");//src下fin.txt文件
     File f = new File("src\fout.txt");//src下fout.txt文件
     
     try {
       FileInputStream fis = new FileInputStream(f);
       FileOutputStream fos = new FileOutputStream(f);
       
       byte[] temp = new byte[];//定义一个字节数组
       fis.read(temp);//读到内存中
       fos.write(temp);//写到文件
       
       fis.close();
       fos.close();
     } catch (FileNotFoundException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     } catch (IOException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     }
     
   }
 }

 package src;
 
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 
 public class Test {
 
   public static void main(String[] args) {
     File f = new File("src\fin.txt");//src下fin.txt文件
     File f = new File("src\fout.txt");//src下fout.txt文件
     
     try {
       FileReader fr = new FileReader(f);
       FileWriter fw = new FileWriter(f);
       
       BufferedReader br = new BufferedReader(fr);
       BufferedWriter bw = new BufferedWriter(fw);
       
       String temp;
       int i=;
       while((temp=br.readLine())!=null){
         bw.write(i+","+temp);
         bw.newLine();//换行
         i++;
       }
       bw.flush();//把缓冲区内容写到文件
       br.close();
       bw.close();
       br.close();
       bw.close();
     } catch (FileNotFoundException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     } catch (IOException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     }
   }
 }

 package src;
 
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.Scanner;
 
 public class Test {
 
   public static void main(String[] args) {
     File f = new File("src\input.txt");
     try {
       FileWriter fw = new FileWriter(f);
       Scanner scanner = new Scanner(System.in);
       String temp;
       while(!((temp=scanner.nextLine()).equals("quit"))){
         fw.write(temp);
       }
       fw.close();
     } catch (IOException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
     }
   }
 }

 package src;
 
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 public class Test {
 
   public static void main(String[] args) {
     File f=new File("src\fin.txt");
     File f=new File("src\fout.txt");
     try {
       FileReader fr=new FileReader(f);
       FileWriter fw=new FileWriter(f);
       
       char temp[]=new char[];
       int len;
       while((len=fr.read(temp))!=-)
       {
         if(len==)
          fw.write(new String(temp)+"n");
         else
           fw.write(temp, , len);
       }
       fr.close();
       fw.close();
       
     } catch (FileNotFoundException e) {
       // TODO 自动生成的 catch 块
       e.printStackTrace();
     } catch (IOException e) {
       // TODO 自动生成的 catch 块
       e.printStackTrace();
     }
   }
 }