Fail to read file and parse with gson when the program packaged as jar

Question

So I am using json to store some data in a txt file. And I use Gson to tackle json. The program went well in eclipse. But when I packaged it into a jar, problem occrurs.

What I did first (in eclipse) is:

        String gsonStr = gson.toJson(masterShips);
        BufferedWriter writer = null;
        try {
            writer = new BufferedWriter(new FileWriter("D:\\master_ship.txt"));
            writer.write(gsonStr);
        } catch (IOException e) {
            System.err.println(e);
        } finally {
            if (writer != null) {
                try {
                    writer.close();
                } catch (IOException e) {
                    System.err.println(e);
                }
            }
        }

Then I copied the .txt file to eclipse and read it using this code:

Scanner in = new Scanner(new FileReader("master_ship.txt"));

String str = in.nextLine();
Log.toDebug(str);
in.close();
JsonParser parser = new JsonParser();
JsonElement je = parser.parse(str);
JsonArray ja = je.getAsJsonArray();
for (int i=0; i<ja.size(); ++i) { 
    ... 
}

But when I put the .jar file and the .txt file in the same folder and excute, error appear. I thought there may be problems with the way of defining the path. Finally I turned to absolute path:

Scanner in = new Scanner(new FileReader("D:\\master_ship.txt"));

Still, it works well in eclipse, but not when using jar. Then I opened the jar with command line:

Exception in thread "main" com.google.gson.JsonSyntaxException: com.google.gson.
stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malform
ed JSON at line 1 column 4
        at com.google.gson.JsonParser.parse(JsonParser.java:65)
        at com.google.gson.JsonParser.parse(JsonParser.java:45)
        at kan.util.Master.loadMasterShip(Master.java:44)
        at kan.util.Master.load(Master.java:27)
        at kan.Main.main(Main.java:22)
Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLeni
ent(true) to accept malformed JSON at line 1 column 4
        at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1505)
        at com.google.gson.stream.JsonReader.checkLenient(JsonReader.java:1386)
        at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:531)
        at com.google.gson.stream.JsonReader.peek(JsonReader.java:414)
        at com.google.gson.JsonParser.parse(JsonParser.java:60)
        ... 4 more

I can be sure that the file is read successfully, because the jar can output the string it read from the file completely. But why should Gson fail outside eclipse while doing good in eclipse.

`writer = new BufferedWriter(new FileWriter("D:\\master_ship.txt"));` We cannot write to resources in a Jar. They are 'read only'. — Andrew Thompson, Dec 25 '13 at 12:29
@AndrewThompson What do you mean? I really don't understand. — bijiDango, Dec 25 '13 at 12:33
Whenever someone asks in a comment shorter than my own *"what do you mean?"*' I think *"WTF don't you understand?"* Now would be a good time for more words, rather than less. — Andrew Thompson, Dec 25 '13 at 12:34
Actually what I thought is "WTF have you said to this quesion, you really read the question?", no offense — bijiDango, Dec 25 '13 at 12:39
None taken. In future, say that (to me). You might want to tone it down a bit for people who are more sensitive than me though.. — Andrew Thompson, Dec 25 '13 at 12:43

score 2 · Answer 1 · edited May 23 '17 at 11:56

2

It has become an embedded-resource. That being the case, the resource must be accessed by URL instead of File. See the info page for the tag, for a way to form an URL.

See also How can an app use files inside the JAR for read and write?

edited May 23 '17 at 11:56

Community

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answered Dec 25 '13 at 12:28

Andrew Thompson

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Please read the question to the end. I correctly wrote and read the file (using debug in eclipse). But problem occurs with gson when using jar. – bijiDango Dec 25 '13 at 12:36
Eclipse probably has not put the resources into a Jar yet. What I can tell you for sure, based on 'resource in Jar' is: A) They are no longer `File` objects, and cannot be treated as such. B) Jars are read only. – Andrew Thompson Dec 25 '13 at 12:40
"But when I put the .jar file and the .txt file in the same folder and excute, error appear." `Scanner in = new Scanner(new FileReader("D:\\master_ship.txt"));`. Actually I noticed it and I used absolute path. (and of course I copy the file to D disk!) PS. I runned the 'absolute path version' and it works well. – bijiDango Dec 25 '13 at 12:42

Fail to read file and parse with gson when the program packaged as jar

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