Maven pom file

Attempt.java

import java.util.Date;
import java.util.HashMap;

public class Attempt {

    private String gamer;
    private Date timestamp;
    private int score;
    private int round;

    public Attempt(String gamer, Date timestamp, int round, int score) {
        this.gamer = gamer;
        this.timestamp = timestamp;
        this.score = score;
        this.round = round;
    }

    public HashMap<String, Object> toMap() {
        HashMap<String, Object> map = new HashMap<>();
        map.put("gamer", gamer);
        map.put("timestamp", timestamp);
        map.put("score", score);
        map.put("round", round);
        return map;
    }
}

Demo.java

import org.apache.http.HttpHost;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.util.Arrays;
import java.util.Date;

public class Demo {

    public static void main(String[] args) throws Exception {

        try (RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")))) {

            IndexRequest request = new IndexRequest("posts", "doc", "1")
                    .source("user", "kimchy",
                            "postDate", new Date(),
                            "message", "trying out Elasticsearch");

            IndexResponse indexResponse = client.index(request, RequestOptions.DEFAULT);
            System.out.println(indexResponse.status());

            GetRequest getRequest = new GetRequest("posts", "doc", "1");
            GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);
            System.out.println(getResponse.getSourceAsString());

            BulkRequest bulkRequest = new BulkRequest();
            bulkRequest.add(new IndexRequest("posts", "doc", "2")
                    .source(XContentType.JSON, "field", "foo"));
            bulkRequest.add(new IndexRequest("posts", "doc", "3")
                    .source(XContentType.JSON, "field", "bar"));
            bulkRequest.add(new IndexRequest("posts", "doc", "4")
                    .source(XContentType.JSON, "field", "baz"));

            BulkResponse bulkResponse = client.bulk(bulkRequest, RequestOptions.DEFAULT);
            System.out.println(!bulkResponse.hasFailures());


            SearchRequest searchRequest1 = new SearchRequest("posts");
            SearchResponse searchResponse1 = client.search(searchRequest1, RequestOptions.DEFAULT);
            System.out.println(Arrays.toString(searchResponse1.getHits().getHits()));


            SearchRequest searchRequest2 = new SearchRequest("posts");
            SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
            sourceBuilder.query(QueryBuilders.termQuery("message", "trying"));
            searchRequest2.source(sourceBuilder);

            SearchResponse searchResponse2 = client.search(searchRequest2, RequestOptions.DEFAULT);
            System.out.println(Arrays.toString(searchResponse2.getHits().getHits()));
        }
    }
}

Game.java

import org.apache.commons.lang3.RandomUtils;
import org.apache.http.HttpHost;
import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;

import java.util.Arrays;
import java.util.Date;
import java.util.List;

public class Game {

    public static void main(String[] args) throws Exception {
        List<String> gamers = Arrays.asList("Jirka", "Honza", "Tonda", "Emil", "Martin");
        int numberOfRounds = 1000;

        try (RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")))) {

            BulkRequest bulkRequest = new BulkRequest();
            for (int round = 0; round < numberOfRounds; round++) {
                Date currentDate = new Date();
                for (String gamer : gamers) {
                    double score = RandomUtils.nextInt(1, 7);
                    Attempt attempt = new Attempt(gamer, currentDate, round, (int) score);

                    IndexRequest indexRequest = new IndexRequest("game", "attempt")
                            .source(attempt.toMap());

                    bulkRequest.add(indexRequest);
                }

                if (round % 100 == 0) {
                    BulkResponse response = client.bulk(bulkRequest, RequestOptions.DEFAULT);
                    System.out.println("Current round " + round + " > " + response.status());

                    bulkRequest = new BulkRequest();
                }
            }

            client.bulk(bulkRequest, RequestOptions.DEFAULT);
        }
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <elasticsearch.version>6.5.1</elasticsearch.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>${elasticsearch.version}</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <version>${elasticsearch.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.5</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>