How to consume REST in Java

Working example, try this:

package restclient;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class NetClientGet {
    public static void main(String[] args) {
        try {

            URL url = new URL("http://localhost:3002/RestWebserviceDemo/rest/json/product/dynamicData?size=5");//your url i.e fetch data from .
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept", "application/json");
            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP Error code : "
                        + conn.getResponseCode());
            }
            InputStreamReader in = new InputStreamReader(conn.getInputStream());
            BufferedReader br = new BufferedReader(in);
            String output;
            while ((output = br.readLine()) != null) {
                System.out.println(output);
            }
            conn.disconnect();

        } catch (Exception e) {
            System.out.println("Exception in NetClientGet:- " + e);
        }
    }
}

As others have said, you can do it using the lower level HTTP API, or you can use the higher level JAXRS APIs to consume a service as JSON. For example:

Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://host:8080/context/rest/method");
JsonArray response = target.request(MediaType.APPLICATION_JSON).get(JsonArray.class);