copyfile.java

读入一个文本文件

import java.io.*;
public class CopyFile
{public static void main(String args[])
   {String sin,sout;
    String infname=args[0];
    String outfname=args[1];
    try{File fin=new File(infname);
        File fout=new File(outfname);
        BufferedReader in=new BufferedReader(new FileReader(fin));
        PrintWriter out=new PrintWriter(new FileWriter(fout));
        sin=in.readLine();
        while(sin!=null)
            {sout=deletecomments(sin);
             if(sout!="0")
               out.println(sout);
             sin=in.readLine();
            }
        in.close();
        out.close();
       }
    catch(FileNotFoundException e1)
        {System.out.println("File not found!");
        }
    catch(IOException e2)
        {e2.printStackTrace(); 
        }
   }
 static String deletecomments(String s)
     {char c;int i=0;
      int pos=s.indexOf("//");
      if((s.length()==0))  return "0";
      for (i=(pos-1);i>=0;i--)
      	  if(s.charAt(i)!=' ') break;
      if(i==-1) return "0";
      if(pos<0)  return s;
      return s.substring(0,pos);
     }
}