我在做文件操作的题（老师布置的）

Question

我来解释一下
就是生成三个文件
先是写上那三个文件
后做把第一第二加上第三
n 时就用cat加在后面
y 时就用cat覆盖

Answer 1

import   java.io.*;
import   java.awt.*;
import   java.awt.event.*;public  class  filework{
public static void copy(InputStream in,OutputStream out) throws IOException{
                    byte[]  buf=new  byte[1024];
                    int  len=in.read(buf);
                    while(len!=-1){
                             out.write(buf,0,len);
                             len=in.read(buf);
                    }
         }
 
         public  static  void  overwritecat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3,true);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
        }
        
       public  static  void  cat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
                    }
public  static  void  main(String args[]) throws IOException { 
         System.out.println("please intput the first file");
         byte  buffer1[]=new   byte[20];
         System.in.read(buffer1,0,20);
            // String  str1=new  String(buffer1);
         File  file1=new  File("e:/javacode/str1.txt");
         boolean  t1=file1.isFile();
         if(t1==false)
         System.out.println("file1 is no exited");         System.out.println("please intput the second file");
         byte  buffer2[]=new   byte[20];
         System.in.read(buffer2,0,20);
         String  str2=new  String(buffer2);
         File  file2=new  File("e:/javacode/str2.txt");
         boolean  t2=file2.isFile();
         if(t2==false)
         System.out.println("file2 is no exited");         System.out.println("please intput the thrid file");
         byte  buffer3[]=new   byte[20];
         System.in.read(buffer3,0,20);
         String  str3=new  String(buffer2);
          File  file3=new  File("e:/javacode/str3.txt");
  //       File  file3=new  File("str3");
         boolean  t3=file3.isFile();
         if(t3==false)
                    System.out.println("file3 is no exited");
         else{
                    System.out.println("you are should you overwrited n/y");
                    String  ch="";
                    StreamTokenizer tokenizer =new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
                    int j=tokenizer.nextToken();
                    if(j==tokenizer.TT_WORD){
                     ch=tokenizer.sval;}
                    if(ch.equals("n")){
                           cat("e:/javacode/str1.txt","e:/javacode/str2.txt","e:/javacode/str3.txt");
                           System.out.println("sucess!")                      
                    }
                    if(ch.equals("y")){
                           overwritecat("e:/javacode/str1.txt","e:/javacode/str2.txt","e:/javacode/str3.txt");
                           System.out.println("sucessoverwrite!");   
                    }            
         }
         
          }
}

Answer 2

import   java.io.*;
import   java.awt.*;
import   java.awt.event.*;public  class  filework{
public static void copy(InputStream in,OutputStream out) throws IOException{
                    byte[]  buf=new  byte[1024];
                    int  len=in.read(buf);
                    while(len!=-1){
                             out.write(buf,0,len);
                             len=in.read(buf);
                    }
         }
 
         public  static  void  overwritecat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3,true);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
        }
        
       public  static  void  cat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
                    }
public  static  void  main(String args[]) throws IOException { 
         System.out.println("please intput the first file");
         String  str1;
         BufferedReader inn1=new BufferedReader(new InputStreamReader(System.in));
         str1=inn1.readLine();
         File  file1=new  File(str1);
         boolean  t1=file1.isFile();
         if(t1==false)
         System.out.println(str1+" is no exsited");         System.out.println("please intput the second file");
          String  str2;
         BufferedReader inn2=new BufferedReader(new InputStreamReader(System.in));
         str2=inn2.readLine();
         File  file2=new  File(str2);
         boolean  t2=file2.isFile();
         if(t2==false)
         System.out.println(str2+" is no exited");         System.out.println("please intput the thrid file");
         String  str3;
         BufferedReader inn3=new BufferedReader(new InputStreamReader(System.in));
         str3=inn3.readLine();
         File  file3=new  File(str3);
         boolean  t3=file3.isFile();
         if(t3==false)
                    System.out.println(str3+" is no exited");
         else{
                    System.out.println("you are should you overwrited n/y");
                    String  ch="";
                    StreamTokenizer tokenizer =new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
                    int j=tokenizer.nextToken();
                    if(j==tokenizer.TT_WORD){
                     ch=tokenizer.sval;}
                    if(ch.equals("n")){
                           cat(str1,str2,str3);
                           System.out.println("sucess!");                      
                    }
                    if(ch.equals("y")){
                           overwritecat(str1,str2,str3);
                           System.out.println("sucessoverwrite!");   
                    }            
            }
         
     }
}

Answer 3

import   java.io.*;
import   java.awt.*;
import   java.awt.event.*;public  class  filework{
public static void copy(InputStream in,OutputStream out) throws IOException{
                    byte[]  buf=new  byte[1024];
                    int  len=in.read(buf);
                    while(len!=-1){
                             out.write(buf,0,len);
                             len=in.read(buf);
                    }
         }
 
         public  static  void  overwritecat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3,true);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
        }
        
       public  static  void  cat(String str1,String str2,String str3){
                    try{
                             InputStream   in1=new   FileInputStream(str1);
                             OutputStream   out1=new   FileOutputStream(str2);
                             copy(in1,out1);
                             in1.close();
                             out1.close();
                             InputStream   in2=new   FileInputStream(str2);
                             OutputStream   out2=new   FileOutputStream(str3);
                             copy(in2,out2);
                             in2.close();
                             out2.close();
                      }catch(IOException  e){
                              System.out.println(e);
                      }
                    }
public  static  void  main(String args[]) throws IOException { 
         System.out.println("please intput the first file");
         String  str1;
         BufferedReader inn1=new BufferedReader(new InputStreamReader(System.in));
         str1=inn1.readLine();
         File  file1=new  File(str1);
         boolean  t1=file1.isFile();
         if(t1==false)
         System.out.println(str1+" is no exsited");         System.out.println("please intput the second file");
          String  str2;
         BufferedReader inn2=new BufferedReader(new InputStreamReader(System.in));
         str2=inn2.readLine();
         File  file2=new  File(str2);
         boolean  t2=file2.isFile();
         if(t2==false)
         System.out.println(str2+" is no exited");         System.out.println("please intput the thrid file");
         String  str3;
         BufferedReader inn3=new BufferedReader(new InputStreamReader(System.in));
         str3=inn3.readLine();
         File  file3=new  File(str3);
         boolean  t3=file3.isFile();
         if(t3==false)
                    System.out.println(str3+" is no exited");
         else{
                    System.out.println("you are should you overwrited n/y");
                    String  ch="";
                    StreamTokenizer tokenizer =new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
                    int j=tokenizer.nextToken();
                    if(j==tokenizer.TT_WORD){
                     ch=tokenizer.sval;}
                    if(ch.equals("n")){
                           cat(str1,str2,str3);
                           System.out.println("sucess!");                      
                    }
                    if(ch.equals("y")){
                           overwritecat(str1,str2,str3);
                           System.out.println("sucessoverwrite!");   
                    }            
            }
         
     }
}