converting json string to java arraylist(using jackson)

Question

I want to convert following json string to java arraylist so that i can get hold of id or name inside docs and make changes in java.

{
 response{
  docs[
   {id:#
    name:#
   }
  ]
 }
}

Didn't you try anything? Like entering your question on google? — home, Feb 07 '13 at 15:55
try this [question](http://stackoverflow.com/questions/1485708/how-do-i-do-a-http-get-in-java) — Oren, Feb 07 '13 at 15:56
Possible duplicate: http://stackoverflow.com/questions/5769717/how-can-i-get-an-http-response-body-as-a-string-in-java — Sotirios Delimanolis, Feb 07 '13 at 15:56
Once you checked the link from @Oren, you might want to have a look at [gson](http://code.google.com/p/google-gson/) — Andreas Fester, Feb 07 '13 at 15:57
and i tried entering on google, i also tried forward and redirect method but does not help. — user1964901, Feb 07 '13 at 16:02

score 1 · Answer 1 · 2013-02-07T16:22:03.687

There are many HTTP client libraries, but given that you're pulling in JSON your best bet is to use the Jersey client library. You need to create a Java object which matches the JSON (in this case, a Response object which contains a field Docs which is an array of Data objects or similar) and tell the Jersey client to expect this as a result. Then you will be able to work with Java objects to output it in whatever form you wish.

*Update

Basic overview of the code. First, set up the Jersey client:

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.api.client.WebResource;

....


final ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
final Client client = Client.create(clientConfig);

Then create your request:

final WebResource webResource = client.resource("http://mydomain.com/myresource");

At this stage, if you want to fetch your JSON back as a String you can just call:

final String json = webResource.get(String.class);

But the real benefit of using Jersey over the other HTTP clients is that it will parse the JSON for you so that you don't need to think about it. If you create the following classes:

public class DataResponse
{
  private final List<DataDoc> docs;

  @JsonCreator
  public DataResponse(@JsonProperty("docs")List<DataDocs> docs)
  {
    this.docs = docs;
  }

  public List<DataDoc> getDocs()
  {
    return this.docs;
  }
}

public class DataDoc
{
  final String id;
  final String name;
  // Other fields go here

  @JsonCreator
  public DataDoc(@JsonProperty("id") String id,
                 @JsonProperty("name") String name)
  {
    this.id = id;
    this.name = name;
  }

  // Getters go here
}

then you can change your Jersey client code to:

final DataResponse response = webResource.get(DataResponse.class);

and you can now access the fields in response as per a normal Java object.

Can you please explain this in coding language. I am not sure how to do this in java, i know i had to do this but failing when code. — user1964901, Feb 07 '13 at 16:04

Achintya Jha · Answer 2 · 2013-02-08T03:35:02.923

1

URL url = new URL("webAddress");

URLConnection conn = url.openConnection();

BufferedReader reader = new BufferedReader(new InputStreamReader(
                conn.getInputStream()));

 String line = "";
 ArrayList<String> list = new ArrayList<String>();
 while ((line = reader.readLine()) != null) {
      list.add(line);

  //Perform operation on your data.It will read a line at a time.

}

edited Feb 08 '13 at 03:35

answered Feb 07 '13 at 15:58

Achintya Jha

12,735
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what will this code do? – user1964901 Feb 07 '13 at 16:07
@user1964901 This code will create a object of URL and pass webAddress to its constructor .After that the connection object is created by invoking the openConnection method on a URL. And bufferedReader will will buffer the input from the specified webAddress. – Achintya Jha Feb 07 '13 at 16:15
so in my case, I am trying to read everything inside docs in json string. so this code will read the whole json file and send me back the data in java as a json string? – user1964901 Feb 07 '13 at 16:22
@user1964901 I edited to read a line at a time. – Achintya Jha Feb 07 '13 at 16:35

score 0 · Answer 3 · edited May 23 '17 at 12:18

0

Actually you want to perform HTTP GET, so take a look on this discussion: How do I do a HTTP GET in Java?

edited May 23 '17 at 12:18

Community

1
1

answered Feb 07 '13 at 15:56

AlexR

114,158
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converting json string to java arraylist(using jackson)

3 Answers3