Where Am I Making Mistake

apurva

Mar 10 2008, 03:24 PM

hello i have just started to learn java by myself and i am stuck here with this example
i want to show a file in console please tell me where am i making mistake.

i am getting erroe variable fin maight not be initialised

here is the code

CODE

/** Display a text file
To use this program,specify the name of file that you want to see
*/
import java.io.*;
class showfile
{
    public static void main(String args[])throws IOException
    {
        int i;
        FileInputStream fin;
        try
            {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter file name:");
            String filename=br.readLine();
            fin=new FileInputStream(filename);

            }
            catch(FileNotFoundException e)
            {
                System.out.println("File not found");
                return;

            }
            catch(ArrayIndexOutOfBoundsException e)
            {
                System.out.println("Ussag:Showfile file");
            }
            //Read characters untill Eof id encountered
            do
            {
               i=fin.read();
                if(i!=-1)
                    System.out.println((char)i);
            }
            while(i!=-1);
            fin.close();
    }
}

Reply

galexcd

Mar 10 2008, 05:25 PM

You are getting that error because it is telling you that fin may not be set since your doing that in the try&catch loop, and then you are doing methods of the FileInputStream class with a variable that possibly may be empty. Put your do-while loop and fin.close(); inside the try, or you could try setting fin to an empty file if you want in the two catches, but I'm not sure if that would work or not. Your best bet is to move the do-while loop and your fin.close();

Reply

CrashCore

Mar 12 2008, 04:37 AM

QUOTE

try
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter file name:");
String filename=br.readLine();
fin=new FileInputStream(filename);

}
catch(FileNotFoundException e)
{
System.out.println("File not found");
return;

}

You have a couple problems yet. First, you should not declare the file input stream in the same try/catch as the BufferedReader on standard input. Separate these. Also, you are continuously redefining the InputStream in the later part of the code, which will make the program simply run an infinite loop. A corrected version of the code would look something like this (depending upon what you wanted it exactly to do):

CODE

/** Display a text file
To use this program,specify the name of file that you want to see
*/
import java.io.*;
class showfile
{
    public static void main(String args[])throws IOException
    {
        int i;
        FileInputStream fin;
        String filename = "";
        try
            {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter file name:");
            filename=br.readLine();


            }
            catch(FileNotFoundException e)
            {
                System.out.println("File not found");
                return;

            }
            catch(ArrayIndexOutOfBoundsException e)
            {
                System.out.println("Ussag:Showfile file");
            }
            //Open the FileInputStream
            try{
            fin=new FileInputStream(filename);
            }
            catch(FileNotFoundException e){
              e.printStackTrace();
              System.out.println("File not found");
              return;
            }
            //Read characters untill Eof id encountered
            do
            {
               i=fin.read();
                if(i!=-1)
                    System.out.println((char)i);
            }
            while(i!=-1);
            fin.close();
    }
}

If you have any questions, just let me know. I hope this helps!

Code tags added around code.

Reply

galexcd

Mar 12 2008, 05:55 AM

Even though its not good programing practice, defining BufferedReader in the try was not causing any error because it was not being referenced at all outside of the block. And as for the infinite loop, that wont happen unless the file is infinitely long which is impossible.

Reply

apurva

Mar 13 2008, 12:17 PM

thanks it worked :-)

Reply

roooss

Apr 20 2008, 02:30 AM

wouldnt it have been to use the scanner class to read a file object line by line? instead of creating buffers and the such?

Reply

vivek mahajan

Jun 1 2008, 09:14 PM

just try it by initializing the "fin" with null.as like fin=null

Reply

coolcat50

Jun 1 2008, 09:26 PM

Well, fin was a file input stream, which cannot be given a value of null. I myself and just learning Java.

Reply

galexcd

Jun 16 2008, 04:11 AM

QUOTE(vivek mahajan @ Jun 1 2008, 01:14 PM)

just try it by initializing the "fin" with null.as like fin=null

Initializing fin to null is no different than initializing it and not setting any value for it. Besides this topic has been resolved.

QUOTE(coolcat50 @ Jun 1 2008, 01:26 PM)

Well, fin was a file input stream, which cannot be given a value of null. I myself and just learning Java.

Well, fin is really just a class, and any class can be null, it just means it is an empty reference to a class with no data in it.

Reply

pandu

Jul 3 2008, 03:06 AM

You know, it's much simpler to use a Scanner. Here:

import java.util.Scanner;

Scanner s=new Scanner(new File("filenamehere.txt"));

String temp;
while(s.hasNext())
{
temp=s.next(); //gives you the next token(word)
System.out.println(temp);
}

Reply

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