Java Community | Help. Code. Learn.•6mo ago

jackson json question

suppose i have json array stored inside the file in the projects variable. how can i update it properly without rewriting it?

18 Replies

JavaBot•6mo ago

⌛ This post has been reserved for your question.

Hey @Koblížkáč! Please use /close or the Close Post button above when your problem is solved. Please remember to follow the help guidelines. This post will be automatically closed after 300 minutes of inactivity.

TIP: Narrow down your issue to simple and precise questions to maximize the chance that others will reply in here.

Peter Rader•6mo ago

You can not update contents of a file without rewriting the contents of a file. Vice versa, if you do not change the file you do not update the file.

KoblížkáčOP•6mo ago

well then, what would be the recommended way to do that with jackson? how can i just update it

Peter Rader•6mo ago

Is it a static file?

KoblížkáčOP•6mo ago

static file?

Peter Rader•6mo ago

I mean: Are you sure the file exists?

KoblížkáčOP•6mo ago

yes

Peter Rader•6mo ago

Try

ObjectMapper om = new ObjectMapper();
var root = om.readValue(projects.toFile(), JsonNode.class);
//change the contents of the root according to your update
FileWriter fw = new FileWriter(projects.toFile());
fw.write(om.writeValueAsString(root));
fw.close();

ObjectMapper om = new ObjectMapper();
var root = om.readValue(projects.toFile(), JsonNode.class);
//change the contents of the root according to your update
FileWriter fw = new FileWriter(projects.toFile());
fw.write(om.writeValueAsString(root));
fw.close();

KoblížkáčOP•6mo ago

@Peter Rader thanks it works, any idea if Path can be converted from string with jackson?

JavaBot•6mo ago

If you are finished with your post, please close it. If you are not, please ignore this message. Note that you will not be able to send further messages here after this post have been closed but you will be able to create new posts.

KoblížkáčOP•6mo ago

i want to deserialize some json to this object:

KoblížkáčOP•6mo ago

and im doing it like this:

Peter Rader•6mo ago

Hm, is this a different question?

KoblížkáčOP•6mo ago

well its unrelated to my first question do i need to make new thread

szatkus•6mo ago

I mean, Jackson could serialize Path just fine. I did it just now.

KoblížkáčOP•6mo ago

where the hell is the problem then

szatkus•6mo ago

No idea, this code works for me:

        ObjectMapper om = new ObjectMapper();
        var a = om.readValue("{\"p\":\"file:///C:/Users/basdfa/Downloads\"}", A.class);
        System.out.println(a.p);

        ObjectMapper om = new ObjectMapper();
        var a = om.readValue("{\"p\":\"file:///C:/Users/basdfa/Downloads\"}", A.class);
        System.out.println(a.p);

JavaBot•6mo ago

💤 Post marked as dormant

This post has been inactive for over 300 minutes, thus, it has been archived. If your question was not answered yet, feel free to re-open this post or create a new one. In case your post is not getting any attention, you can try to use /help ping. Warning: abusing this will result in moderative actions taken against you.

Gaming

Programming

jackson json question