Fat Jar throwing File not found exception when trying to access text file within the jar - maven

Question

I have built a Spring boot MVC application with a Tree data structure in place of an actual database. The program reads from a text file and stores words in the tree. originally I used a the CommandLineRunner class to populate the tree, which works... but after creating a fat jar and running the jar, I get a file not found exception. how can I build a fat jar with maven that includes the text file with maven?
the file is currently in the project root.
here is the logic to generate the tree:
#Component
#Order(value = Ordered.HIGHEST_PRECEDENCE)
public class GenerateTree implements CommandLineRunner {
#Autowired
TreeRepository trie = new TreeRepository();
#Autowired
FileReader fileReader = new FileReader();
#Override
public void run(String... args) throws Exception {
for (String s : fileReader.readFile("wordList1.txt")){
trie.add(s);
}
}
}
here is the logic that reads in the file:
#Component
public class FileReader {
List<String> readFile(String filename){
List<String> list = new ArrayList<>();
try (Stream<String> stream = Files.lines(Paths.get(filename))) {
list = stream
.filter(line -> line.matches("[a-zA-Z]+"))
.collect(Collectors.toList());
} catch (IOException e) {
e.printStackTrace();
}
return list;
}
}

Answer 1

You cannot access a File inside a jar (see https://stackoverflow.com/a/8258308/4516887).
Put the wordlist.txt into the src/main/resources directory and read its contents using a [ClassPathResource][1]:
ClassPathResource resource = new ClassPathResource("worldlist.txt");
try (InputStream in = resource.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in))) {
String line;
while((line = reader.readLine()) != null) {
...
}
}