CODEWITHSUNDEEP
javaeclipse
user3133542
user3133542

Reputation: 1715

Reading a Txt-File in a jar-File in Java

I've write a Java programm and packaged it the usual way in a jar-File - unfortunately is needs to read in a txt-File. Thats way the programm failed to start on other computer machines because it could not find the txt-file.

At the same time Im using many images in my programm but here there is no such problem: I "copy" the images to the eclipse home directory, so that they are packaged in the jar-File and usable through following command:

BufferedImage buffImage=ImageIO.read(ClassName.class.getClassLoader()
                    .getResourceAsStream("your/class/pathName/));

There is something similar for simple textfiles which then can be use as a normal new File()?

Edit
Ive try to solve my problem with this solution:

package footballQuestioner;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import javax.security.auth.login.Configuration;


public class attempter {

    public static void main(String[] args) {
        example ex = new example();
    }

}

class example  {



    public example() {

        String line = null;

        BufferedReader buff = new BufferedReader(new InputStreamReader(
                Configuration.class
                        .getResourceAsStream("footballQuestioner/BackUpFile")));

        do {
            try {
                line = buff.readLine();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } while (line != null);

    }

}

But it gives always an NullPointerException...do I have forgotten something?

Here is as required my file structure of my jar-File:

enter image description here enter image description here enter image description here enter image description here

Upvotes: 1

Views: 179

Answers (2)

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285430

There are no "files" in a jar but you can get your text file as a resource (URL) or as an InputStream. An InputStream can be passed into a Scanner which can help you read your file.

You state:

But it gives always an NullPointerException...do I have forgotten something?

It means that likely your resource path, "footballQuestioner/BackUpFile" is wrong. You need to start looking for the resource relative to your class files. You need to make sure to spell your file name and its extension correctly. Are you missing a .txt extension here?

Edit
What if you try simply:

BufferedReader buff = new BufferedReader(new InputStreamReader(
            Configuration.class.getResourceAsStream("BackUpFile")));

Upvotes: 1

treeno
treeno

Reputation: 2600

You can load the file from the ClassPath by doing something like this:

ClassLoader cl = getClass().getClassLoader()
cl.getResourceAsStream("TextFile.txt");

this should also work:

getClass().getResourceAsStream(fileName);

File always points to a file in the filesystem, so I think you will have to deal with a stream.

Upvotes: 2

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