Apache CLI, Executable jar, classLoader().getResource()

Question

My goal is to use Apache CLI with an executable jar file to read in a text file, perform string manipulations, and then write to a CSV. You would execute the tool in the terminal like this:

$ java -jar my-tool-with-dependencies.jar -i input.txt -o output.csv

I've written tests for this functionality and those tests are passing. The test input text file is located in src/test/resources/. The following test is passing:

@Test
public void testWordockerWriteCsvFileContents() {
// Make sure the csv file contains contents

Wordocker w = new Wordocker();

String intext = "/textformat/example_format.txt";
String outcsv = "/tmp/foo.csv";

w.writeCsvFile(intext, outcsv);

try {

Reader in = new FileReader(outcsv);
Iterable<CSVRecord> records = CSVFormat.DEFAULT.parse(in);
for (CSVRecord record : records) {
    assertTrue(record.toString().length() > 0);
}
} catch(FileNotFoundException e){
    assertTrue(false);
} catch(IOException e) {
    assertTrue(false);
}

File file = new File(outcsv);
if (file.exists()) {
    file.delete();
}

}

We I compile my jar files with dependencies using mvn clean compile assembly:single then I raise the following FileNotFoundException:

    // Get file from resources folder
    URL resourceURL = ParseDoc.class.getClassLoader().getResource(fileName);

    if (resourceURL == null) {
    throw new FileNotFoundException(fileName + " not found");
    }
    file = new File(resourceURL.getFile());

This leads me to believe that there is an issue with where ParseDoc.class.getClassLoader().getResource(fileName); is looking for the file. I'm aware of related questions which have been asked. Related questions are the following:

None of these questions appear to ask about how to use an executable jar with Apache CLI. I think the basic issue is that the filepath given by my command line argument cannot be found by URL resourceURL = ParseDoc.class.getClassLoader().getResource(fileName);.

Please let me know what you think. Thank you for your time.

Why are you not using FileReader as in your tests? GetResource only finds files that are packaged within the jar-file, is this what you are trying to do? — centic, Nov 25 '15 at 20:10
definitely not, it sounds like FileReader would be the thing to do. — Tyler, Nov 25 '15 at 20:24

score 0 · Accepted Answer · answered Nov 26 '15 at 07:57

I'm posting this as answer as well after discussion via comments:

Classloader.getResource() is only fetching files that are packaged as part of the Jar-file or located in the classpath-folders.

For reading a normal file you would use something like your first example, i.e. FileReader or FileInputStream or simply pass a java.io.File depending on what the library that you are trying to use supports.

Apache CLI, Executable jar, classLoader().getResource()

1 Answers1