Getting nullpointerexception while reading file from resource folder

Question

I am getting NullpointerException when I try to read the file present in src/main/resources location. It occurs when I run in jar format. But when I compile the code and run it , its running fine in Intellij.

Note: I am using sbt package to build the jar and running it.

Please help out. thanks!

Post your code. Otherwise, we're just guessing as to what the program might be doing. — The Archetypal Paul
– The Archetypal Paul, Commented Oct 22, 2018 at 13:16
configFileName = CustomParams.dbName + "_" + CustomParams.tableName + "_config.conf" println("configFileName "+configFileName) //check in resource and get the path of it //println("ssdfs " +Thread.currentThread.getContextClassLoader.getResource(s"/$configFileName").getFile) val filePath = DqDriver.getClass.getClassLoader.getResource(s"$configFileName").getFile — A srinivas
– A srinivas, Commented Oct 22, 2018 at 13:22
thanks for your time. I got the solution from another suggestion! — A srinivas
– A srinivas, Commented Oct 22, 2018 at 13:47

Markus Appel · Accepted Answer · 2018-10-22 14:14:34Z

2

Files that have been packed into the JAR are not accessible from the file system anymore. This can be seen when looking at the URL returned from myClass.getResource("file.txt"), e.g.:

/home/sria/cde-spark-assembly-1.0.jar!/file.txt

Note the ! denoting that the file is packaged into the JAR.

This means you always have to access resource files using the following pattern:

For a file in src/main/resources/file.txt:

myClass.getResourceAsStream("file.txt")

There is two reasons why you might not want to do that:

Adding files to the resources directory will increase the JAR file size.
The file cannot be accessed using standard file system operations.

As an alternative you can load the file from a (configurable) path in the file system, using for example:

val inputStream = new BufferedInputStream(new FileInputStream(myPath))

(reference)

This way you can load a file, e.g. relative to the JAR file path or the execution directory.

I hope this helps.

Note: Both sbt package and sbt assembly will package resource files into the JAR.

edited Oct 22, 2018 at 14:14

answered Oct 22, 2018 at 12:55

Markus Appel

3,2682 gold badges23 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

A srinivas Over a year ago

I tried running with assembly too. I am getting the path like this /home/sria/cde-spark-assembly-1.0.jar!/config.conf . there is an exclamatory coming from no where.

Markus Appel Over a year ago

@A srinivas that's correct. This path denotes that the given file is packed into the JAR. It cannot be treated as a normal file, and should be retrieved using getResourceAsStream.

A srinivas Over a year ago

thanks.. its working fine now. but do you know any alternative for fat jar, as its not effective to transfer the fat jar from local to remote everytime?

Markus Appel Over a year ago

@Asrinivas I adapted my answer accordingly.

Collectives™ on Stack Overflow

Getting nullpointerexception while reading file from resource folder

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related