File not opening in Java

Question

Im trying to read a simple text file with contents input.txt

Line 1
Line 2
Line 3

But it always goes to the exception and prints Error.

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String args[]){

        List<String> text = new ArrayList<String>();
        try{
            BufferedReader reader = new BufferedReader(new FileReader("input.txt"));
            for (String line; (line = reader.readLine()) != null; ) {
                 text.add(line);
            }
            System.out.println(text.size()); //print how many lines read in
            reader.close();
        }catch(IOException e){
            System.out.println("ERROR");
        }
    }   
}

Im using Eclipse as my IDE if that makes a difference. I've tried this code on http://www.compileonline.com/compile_java_online.php and it runs fine, why wont it run in Eclipse?

Try printing out the exception. Then you'll know what the error actually is. — Reinstate Monica -- notmaynard, Jun 21 '13 at 21:54
I'm guessing `FileNotFoundException` - but yes, you should never ignore the exception itself. — Jon Skeet, Jun 21 '13 at 21:54
If you dont understand others comments then they mean to use `catch{e.printStackTrace()....}` — Smit, Jun 21 '13 at 21:58
Actually,`SOP("ERROR")` went me directly to [this link](http://stackoverflow.com/questions/184618/what-is-the-best-comment-in-source-code-you-have-ever-encountered/549611#549611) :) — Azad, Jun 21 '13 at 22:16

score 1 · Answer 1 · answered Jun 21 '13 at 21:59

1

give complete file path like "C:\\folder_name\\input.txt" or place input.txt inside src directory of eclipse project.

answered Jun 21 '13 at 21:59

Pravat Panda

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its inside the src folder already, ill try using the full file path – Eduardo Jun 21 '13 at 22:02
full path not required if txt file is inside src(classpath). Try printing out the exception using e.printStackTrace(); – Pravat Panda Jun 21 '13 at 22:04
It says the system cannot find the file specified – Eduardo Jun 21 '13 at 22:07
the full path works, but i would rather have a way to refer to the current directory – Eduardo Jun 21 '13 at 22:07
1

**NOTE:** use `slash(/)` instead `backslash(\\)` because of different platforms. – Azad Jun 21 '13 at 22:09
see this question http://stackoverflow.com/questions/1464291/how-to-really-read-text-file-from-classpath-in-java – Pravat Panda Jun 21 '13 at 22:10
have you found the solution? – Pravat Panda Jun 21 '13 at 22:34
Use `System.getProperty("user.dir")` to get running directory. Also, use `java.io.File.separator` instead of `\\` or `/` to be platform-independent: `System.getProperty("user.dir")+File.separator+"input.txt"`. – Matthieu Jun 22 '13 at 07:54

score 1 · Answer 2 · answered Jun 21 '13 at 21:59

public class Main {
    public static void main(String args[]){

        List<String> text = new ArrayList<String>();
        try{
            BufferedReader reader = new BufferedReader(
                    new FileReader("input.txt"));  //<< your problem is probably here, 
            //More than likely you have to supply a path the input file.
            //Something like "C:\\mydir\\input.txt"
            for (String line; (line = reader.readLine()) != null; ) {
                 text.add(line);
            }
            System.out.println(text.size()); //print how many lines read in
            reader.close();
        }catch(IOException e){
            System.out.println("ERROR"); //This tells you nothing.
            System.out.println(e.getMessage());  //Do this
            //or 
            e.printStackTrace(); //this or both

        }
    }   
}

What you are doing does refer to the current directory, but I _suspect_ that is your problem. Until you have the stack trace you don't really know. — Pete B., Jun 21 '13 at 22:05

Thorbjørn Ravn Andersen · Answer 3 · 2013-06-22T07:41:55.663

You most likely have a bad path. Consider this main instead:

public class Main {
    public static void main(String args[]) throws Exception {

        List<String> text = new ArrayList<String>();

        BufferedReader reader = new BufferedReader(new FileReader("input.txt"));
        for (String line; (line = reader.readLine()) != null; ) {
             text.add(line);
        }
        System.out.println(text.size()); //print how many lines read in
        reader.close();
    }   
}

The "throws Exception" addition allows you to focus on the code, and consider better error handling later. Also consider using File f = new File("input.txt") and use that, because it allows you to print out f.getAbsolutePath() which tells you the filename it was actually looking for.

The code you posted doesn't compile. `public class Main throws Exception {` is wrong, maybe you were talking about `public static void main(String args[]) throws Exception {`? — BackSlash, Jun 21 '13 at 22:05

score 0 · Answer 4 · answered Jun 21 '13 at 22:14

0

Changing input.txt to src\\input.txt solved the problem! I guess it was because the current directory isnt actually the src folder its the parent,

Thanks for the help!

answered Jun 21 '13 at 22:14

Eduardo

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When you just say `input.txt` then it will start looking in its root folder (where your src and other project related folder resides ), that means your project folder. When you say `src\\input.txt` that means `root folder\src\input.txt`. – Smit Jun 21 '13 at 22:24

File not opening in Java

4 Answers4