Error : Analytics Reporting API V4 has not been used in project

I am trying to access my Analytics data from a JAVA code. But when the following code is run,

package com.test.googleapi;

import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.analyticsreporting.v4.AnalyticsReporting;
import com.google.api.services.analyticsreporting.v4.model.DateRange;
import com.google.api.services.analyticsreporting.v4.model.Dimension;
import com.google.api.services.analyticsreporting.v4.model.GetReportsRequest;
import com.google.api.services.analyticsreporting.v4.model.GetReportsResponse;
import com.google.api.services.analyticsreporting.v4.model.Metric;
import com.google.api.services.analyticsreporting.v4.model.ReportRequest;

public class AnalyticsApiTest {
    public static void main(String[] args) throws Exception {
        GoogleCredential credential = GoogleCredential
                .fromStream(new FileInputStream(new File("assets/client-secrets/service-account-key.json")))
                .createScoped(Collections.singleton("https://www.googleapis.com/auth/analytics.readonly"));
        HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
        AnalyticsReporting analyticsReporting = new AnalyticsReporting.Builder(httpTransport, jsonFactory, credential)
                .setApplicationName("Test")
                .build();

        DateRange dateRange = new DateRange();
        dateRange.setStartDate("2015-06-15");
        dateRange.setEndDate("2015-06-30");

        // Create the Metrics object.
        Metric sessions = new Metric()
            .setExpression("ga:sessions")
            .setAlias("sessions");

        //Create the Dimensions object.
        Dimension browser = new Dimension()
            .setName("ga:browser");

        // Create the ReportRequest object.
        ReportRequest request = new ReportRequest()
            .setViewId("XXXX")
            .setDateRanges(Arrays.asList(dateRange))
            .setDimensions(Arrays.asList(browser))
            .setMetrics(Arrays.asList(sessions));

        ArrayList<ReportRequest> requests = new ArrayList<ReportRequest>();
        requests.add(request);

        // Create the GetReportsRequest object.
        GetReportsRequest getReport = new GetReportsRequest()
            .setReportRequests(requests);

        // Call the batchGet method.
        GetReportsResponse response = analyticsReporting.reports().batchGet(getReport).execute();

    }
}

I get the following error:

Exception in thread "main" com.google.api.client.googleapis.json.GoogleJsonResponseException: 403 Forbidden
{
  "code" : 403,
  "errors" : [ {
    "domain" : "global",
    "message" : "Analytics Reporting API V4 has not been used in project analytics-test-1279 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/analyticsreporting.googleapis.com/overview?project=analytics-test-1279 then retry. If you enabled this API recently, wait a few minutes for the action to propagate to our systems and retry.",
    "reason" : "forbidden"
  } ],
  "message" : "Analytics Reporting API V4 has not been used in project analytics-test-1279 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/analyticsreporting.googleapis.com/overview?project=analytics-test-1279 then retry. If you enabled this API recently, wait a few minutes for the action to propagate to our systems and retry.",
  "status" : "PERMISSION_DENIED"
}
    at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:145)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:113)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:40)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:321)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1056)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
    at com.test.googleapi.AnalyticsApiTest.main(AnalyticsApiTest.java:73)

I have already setup a Service Account Key in the analytics-test-1279 project. The Analytics API is also enabled.

I could not figure out what exactly is the problem here.

Solution

As stated in the error message, you need to enable the Analytics Reporting API. They handily provided you with a direct link in the error to the same page.

From your screenshot you have enabled the Analytics API. Which contains the Management API V3 and the old Core Reporting API V3.

With the release of Analytics Reporting API V4 you need to enable the completly new API. The good news is that authorize still uses the same scopes so there will be no need for your users to re-authorize your application.