Reader/getResourceAsStream returns null

Question

I'm trying to read from a json file to a reader in order to parse it into a java object:`

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class main {

    public static void main(String[] args) throws IOException{

        try(Reader reader = new InputStreamReader(main.class.getResourceAsStream(
               "/Users/edwardk/IdeaProjects/practice_json/small_incidents.json"),"UTF-8")){
            Gson gson = new GsonBuilder().create();
            Person p = gson.fromJson(reader, Person.class);
            System.out.println(p);
        }
    }
}

`

Im getting a NullPointerException on run.

getResourceAsStream() gets a resource, from the classpath. To read a file, from the file system, use a FileInputStream. — JB Nizet, Jul 03 '17 at 18:59

dimo414 · Answer 1 · 2017-07-03T23:15:10.170

Resources are not files, and that path /Users/edwardk/... looks like a file path.

You should use the Files API to read from a file, and if you're on Windows your path will need to start with C:/, not /. If you intended to load the file as a reasource you should use a path to the file relative to your classpath. For example if the practice_json directory is on your classpath you may just need to use "small_incidents.json".

score 1 · Answer 2 · answered Jul 03 '17 at 19:15

1

Your code is good, but NullPointerException arises because

main.class.getResourceAsStream(
               "/Users/edwardk/IdeaProjects/practice_json/small_incidents.json"),"UTF-8")

returns null. Try to paste json file into same directory as main.java and change :

main.class.getResourceAsStream(
               "small_incidents.json"),"UTF-8")

Or specify correct relative path to small_ingredients.json

answered Jul 03 '17 at 19:15

Jay Smith

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This was indeed the problem, I've resolved it by moving the json file to the Recourses directory. – ksilla Jul 03 '17 at 19:55

Reader/getResourceAsStream returns null

2 Answers2