Solved

Writing to a file

Posted on 2004-04-10
10
531 Views
Last Modified: 2010-03-31
I need to read in a file, and then create a file which includes the first file content.  For example i read file A which contains

abc
def

then i need to read in, and then create a file which has the format:

1: abc
2: def

any idea?
0
Comment
Question by:jtcy
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
  • 5
10 Comments
 
LVL 92

Expert Comment

by:objects
ID: 10796070
BufferedReader in = new BufferedReader(new FileReader("in.txt"));
PrintWriter out = new PrintWriter(new FileReader("out.txt"));
String line = null;
int lineno = 1;
while (null!=(line=in.readLine()))
{
   out.println(lineno+": "+line);
   lineno++;
}
in.close();
out.close();

0
 

Author Comment

by:jtcy
ID: 10796272
I have this method in class Parser,

public void writeFile(FileReader in) throws java.io.IOException
    {
          FileWriter writer = new FileWriter("LISTING.txt");
          PrintWriter out = new PrintWriter(writer);
          
          BufferedReader inFile = new BufferedReader(in);
          String line = inFile.readLine();
          
          int j = 1;
          while (line != null)
           {
                 System.out.println(line);
                 out.println(j+ " :" + line);
                 j++;
           }
          
          inFile.close();
            out.close();

    }

then in driver class, i do:

parser.writeFile(inFile);

the Listing file did create but is still blank~ :~(
0
 
LVL 92

Accepted Solution

by:
objects earned 500 total points
ID: 10796285
that won't work cause you don't read the next line in your loop.

should be more like:

public void writeFile(FileReader in) throws java.io.IOException
    {
         FileWriter writer = new FileWriter("LISTING.txt");
         PrintWriter out = new PrintWriter(writer);
         
         BufferedReader inFile = new BufferedReader(in);
         String line =null;
         
         int j = 1;
         while ((line = inFile.readLine())!= null)
          {
               System.out.println(line);
               out.println(j+ " :" + line);
               j++;
          }
         
         inFile.close();
          out.close();

    }
0
PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now

 

Author Comment

by:jtcy
ID: 10796296
I changed it, still doesnt work. 0kb file produced~
0
 

Author Comment

by:jtcy
ID: 10796305
FileWriter writer = new FileWriter("LISTING.txt");
          PrintWriter out = new PrintWriter(writer);
          
          BufferedReader inFile = new BufferedReader(in);
          String line = null;
        System.out.println(inFile.readLine()); // I do a test here

and it seems like the file read in is null. how can that be. i am very sure the file is not null. Could it be perhaps we cant pass Filereader object as parameter?
0
 
LVL 92

Expert Comment

by:objects
ID: 10796308
SOunds like either the file you are reading is empty, or you have already read all it's contents.
0
 
LVL 92

Expert Comment

by:objects
ID: 10796313
Make sure you haven't already been reading from the FileReader you are passing in.
0
 

Author Comment

by:jtcy
ID: 10796325
>> Make sure you haven't already been reading from the FileReader you are passing in.


cool. solved it.
0
 
LVL 92

Expert Comment

by:objects
ID: 10796344
0
 

Author Comment

by:jtcy
ID: 10796346
hey, u're my senior LOL
0

Featured Post

Instantly Create Instructional Tutorials

Contextual Guidance at the moment of need helps your employees adopt to new software or processes instantly. Boost knowledge retention and employee engagement step-by-step with one easy solution.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Adding multiple JVM environments to RedHat 6 7 82
Selenium docs api java index 3 98
program arguments vs VM arguments 4 57
IBM TS2900 (3572) Tape Autoloader Java? 12 109
Java had always been an easily readable and understandable language.  Some relatively recent changes in the language seem to be changing this pretty fast, and anyone that had not seen any Java code for the last 5 years will possibly have issues unde…
Introduction This article is the last of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers our test design approach and then goes through a simple test case example, how …
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
This tutorial will introduce the viewer to VisualVM for the Java platform application. This video explains an example program and covers the Overview, Monitor, and Heap Dump tabs.
Suggested Courses

751 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question