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FileReader & PrintWriter

Posted on 2004-04-10
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Last Modified: 2011-10-03
Can a FileReader object get written twice? I just create a file using PrintWriter with a FileReader object as its argument. Result of that is a file created. Then i need to write something to that file which just created. So i create a printWriter object again with that FileReader object. But that doesnt work. Can someone help?

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

    }

so I first call
writeFile(inFile);
then i do:

PrintWriter err = new PrintWriter(parser.writer);
            // add any error messages to the listing file...

                for (int i=0; i<parser.errors.size(); i++)
                 {
                       String k = (String)parser.errors.get(i);
                       err.println(k);
                 }
               
                err.close();

the problem is nothing being added to the file which just created.
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Question by:jtcy
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5 Comments
 
LVL 86

Accepted Solution

by:
CEHJ earned 200 total points
ID: 10796583
The easiest way is to siimply append the error messages:

PrintWriter out = new PrintWriter(new FileWriter("yourFile.log", true)); // open for append
out.println("Extra info");
out.close();

0
 
LVL 92

Assisted Solution

by:objects
objects earned 300 total points
ID: 10799178
Have your writeFile method return your PrintWriter so you can continue to write to the file:

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

    }
0
 
LVL 92

Assisted Solution

by:objects
objects earned 300 total points
ID: 10799184
You'd then write your errors using:

PrintWriter err = writeFile(inFile);
// add any error messages to the listing file...

for (int i=0; i<parser.errors.size(); i++)
{
        String k = (String)parser.errors.get(i);
        err.println(k);
}
             
err.close();
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 10812283
8-)
0
 
LVL 92

Expert Comment

by:objects
ID: 10817893
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