Java

joegumbo · 09-29-2008, 12:38 AM

Hi,

This is part of an assignment, so I would like advice on this without actually solving this for me. Thanks.

I'm trying to read from two text files into an array:

Scanner billsOf2006Scanner = new Scanner(new File("billsOf2006.txt"));
for (int k = 0; k < 12; k++)
{
year2006[k]=billsOf2006Scanner.nextDouble();
}

Even when I include the full path, I still keep getting the same error messages:

Exception in thread "main" java.io.FileNotFoundException: billsOf2006.txt (No such file or directory)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:106)
at java.util.Scanner.<init>(Scanner.java:636)
at TheArrayProgram.main(TheArrayProgram.java:47)

------------------
(program exited with code: 1)
Press return to continue

I've tried /home/username/TheArrayProgram.java/billsOf2006.txt

as well as appending first file:///home/blahblah and File:///home/blahblah

My text file is in the same directory as the program, but the program cannot find it.

Btw, this is on Slackware 12.1.

Thanks,
-Joe G.

Btw, upon further viewing, I get the impression that this could be more of a Linux question, rather than a Java question. If I remember correctly, all that should be necessary in Windows is for the text files to be included in the same folder as the program.java file. But, maybe I'm wrong?

Thanks,
-Joe

paulsm4 · 09-29-2008, 01:23 AM

Hi -

It *should* work OK... but there are a couple of potential "gotcha's" here:

1. Linux is case-sensitive: if the file isn't spelled *exactly* as you specified in your program, it will fail

2. If you're using Java packages, you might not be in the directory you expect to be in

3. Etc etc

SUGGESTION:
Try - and adapt - this code snippet to further debug the problem:

Code:

import java.io.*;

public class Test
{
  public static void main (String[] args)
  {
     String fname = "billsOf2006.txt";
     File f = new File (fname);
     if (f.exists ())
       System.out.println ("SUCCESS: " + fname + " exists!");
     else
       System.out.println ("WARNING: " + fname + " doesn't exist!");
  }
}

'Hope that helps .. PSM

linuxer8786 · 09-29-2008, 03:56 AM

you missing FileInpuStream and FileReader

Linux Archive

joegumbo · 09-29-2008, 08:19 AM

This is from the compiler:

----jGRASP exec: javac -g /home/joegumbo/Documents/CIT-130-NC61W/Test/Test.java
Test.java:15: cannot find symbol
symbol : variable billsOf2006
location: class Test
File f = new File (billsOf2006.txt);
^
Test.java:17: cannot find symbol
symbol : variable billsOf2006
location: class Test
System.out.println ("SUCCESS: " + billsOf2006.txt + " exists!");
^
Test.java:19: cannot find symbol
symbol : variable billsOf2006
location: class Test
System.out.println ("WARNING: " + billsOf2006.txt + " doesn't exist!");
^
3 errors

----jGRASP wedge: exit code for process is 1.
----jGRASP: operation complete.

This is the program output:

----jGRASP exec: java Test
WARNING: billsOf2006.txt doesn't exist!

----jGRASP: operation complete.

I've checked and rechecked the spelling many times.

Thank you paulsm4!

-Joe

Hi linuxer8786!

I have to get out of the house and go to work. I'll check into those libraries later today when I get home.

These are my import statements:

import java.io.*;
import static java.lang.System.*;
import java.util.*;
import java.util.Scanner;
import java.io.File;
import java.io.File.*;
import java.io.IOException;

If those libraries aren't there, then where are they?

Thanks,
-Joe

linuxer8786 · 09-29-2008, 09:24 AM

Quote:

Originally Posted by joegumbo

This is from the compiler:

----jGRASP exec: javac -g /home/joegumbo/Documents/CIT-130-NC61W/Test/Test.java
Test.java:15: cannot find symbol
symbol : variable billsOf2006
location: class Test
File f = new File (billsOf2006.txt);
^
Test.java:17: cannot find symbol
symbol : variable billsOf2006
location: class Test
System.out.println ("SUCCESS: " + billsOf2006.txt + " exists!");
^
Test.java:19: cannot find symbol
symbol : variable billsOf2006
location: class Test
System.out.println ("WARNING: " + billsOf2006.txt + " doesn't exist!");
^
3 errors

----jGRASP wedge: exit code for process is 1.
----jGRASP: operation complete.

This is the program output:

----jGRASP exec: java Test
WARNING: billsOf2006.txt doesn't exist!

----jGRASP: operation complete.

I've checked and rechecked the spelling many times.

Thank you paulsm4!

-Joe

Hi linuxer8786!

I have to get out of the house and go to work. I'll check into those libraries later today when I get home.

These are my import statements:

import java.io.*;
import static java.lang.System.*;
import java.util.*;
import java.util.Scanner;
import java.io.File;
import java.io.File.*;
import java.io.IOException;

If those libraries aren't there, then where are they?

Thanks,
-Joe

It in java.io
you try something:
File file = new File("abc");
FileInputStream fis = new FileInputStream(file);
BufferedInputStream buf = new BufferedInputStream(fis);

paulsm4 · 09-29-2008, 11:24 AM

joegumbo -

Please ignore linuxer8786 for the time being. You're going to need "FileInputStream()" et al (or something like it) soon, but it's not the first problem we need to resolve. I deliberately wanted you to focus on the "File" object, for two reasons:
a) We need to "get it right" before we go any further
b) Understanding the distinction between "File", "Stream" and "Scanner" classes is *extremely* important (and very useful!)

Also, you've got way too many imports. They're not "bad" .. but they're not required, either.

Please cut/paste this version of "Test.java" exactly as-is, and try to build it:

Code:

import java.io.*;

public class Test
{
  public static void main (String[] args)
  {
     // Check whether or not this file exists in this directory
     String fname = "billsOf2006.txt";
     File f = new File (fname);
     if (f.exists ())
       System.out.println ("SUCCESS: " + fname + " exists!");
     else
       System.out.println ("WARNING: " + fname + " doesn't exist!");
     /*
      * NOTE: 
      * A Java "File" object is just something on a filesystem - it's *not* 
      * necessarily a "text file", and it doesn't necessarily even have to exist!
      */

     // Print out the working directory
     System.out.println ("user.dir= " + System.getProperty("user.dir") + "...");

     // List all files in this directory
     File dir = new File(".");
     String[] children = dir.list();
     if (children != null) 
     {
       System.out.println ("#/files and subdirectories= " + children.length + "...");
       for (int i=0; i < children.length; i++) 
         System.out.println ("  " + children[i] + "...");
     }
     System.out.println ("Done.");
  }
}

Here's sample output:

Quote:

javac -g Test.java
java Test
WARNING: billsOf2006.txt doesn't exist!
user.dir= C:\temp\temp2...
#/files and subdirectories= 2...
Test.class...
Test.java...
Done.

You should *not* get any warnings or errors.

joegumbo · 09-29-2008, 02:26 PM

It compiled and output!!

Thank you!

I know you asked me not to make any changes, but sometimes a blank slate is easier.

I made a new directory named TestA;
I changed the program name to TestA.java;
I changed the text fnames to a.txt and b.txt;
I saved a.txt , b.txt and TestA.java in TestA
I enclosed fname in double quotes wherever I found it in TestA.java

It compiled error free.

This is the output from the program:

SUCCESS: a.txt exists!
user.dir= /home/joegumbo/Documents/TestA...
#/files and subdirectories= 5...
a.txt...
b.txt...
TestA.java...
geany_run_script.sh...
TestA.class...
Done.

------------------
(program exited with code: 0)
Press return to continue

paulsm4... You are a genius!

joegumbo · 09-29-2008, 02:46 PM

I went back into my original program and changed the text file names to a.txt and b.txt . I'm only guessing, but it seems that Java just doesn't like numbers in a text file name it's reading from.

It's compiling and spitting out the data I'm requesting!

Thank you again, paulsm4!

Thank you too linuxer8786, for trying to help!

paulsm4 · 09-29-2008, 03:54 PM

Hi -

In problems like this, you've just got to break things down, a step at a time.

It sounds like you've got a handle on the "file not found" step - cool!

The next step is to do exactly what linuxer8786 suggested:

a) use the file to open a "stream"
b) pass the stream as input to your "Scanner" class

Here's an example:
http://java.sun.com/docs/books/tutor.../scanning.html

'Hope that helps .. PSM

PS:
Java has no problems with digits in filenames. But there are lots of other problems you might run into. I mentioned "case sensitivity" above. Another pop favorite is "spaces in the file name".

Anyway - it sounds like you're on the right track. Good luck!

joegumbo · 09-29-2008, 05:12 PM

Actually, I'm done!!!!

I didn't need to do anything else to enter the filenames into the array.

I'm just now printing out my results for class tomorrow!!

Thank you!!!!!

-Joe