TimSin

XContentBuilder settings = // ...create settings JSON object
XContentBuilder mapping = // ...build mapping JSON object

CreateIndexRequestBuilder irb = client.admin().indices().prepareCreate(INDEX_NAME);
irb.setSettings(settings);
irb.execute().actionGet();

PutMappingResponse response = client.admin().indices()
  .preparePutMapping(INDEX_NAME).setType(TYPE_NAME)

TimSin

        Client client = new TransportClient().addTransportAddress(new InetSocketTransportAddress(
                "localhost", 9300));

        XContentBuilder mapping = XContentFactory.jsonBuilder()
                .startObject()
                    .startObject("mappings")
                        .startObject("testobject")
                            .startObject("properties")
                                .startObject("key")
                                    .field("type", "string")