Here is the class. You need to create a bucket called "geo" for this to work

CouchbaseActivityDao.java

package com.folion.activity.dao;

import com.couchbase.client.core.time.Delay;
import com.couchbase.client.java.Bucket;
import com.couchbase.client.java.Cluster;
import com.couchbase.client.java.CouchbaseCluster;
import com.couchbase.client.java.document.RawJsonDocument;
import com.couchbase.client.java.error.CASMismatchException;
import com.couchbase.client.java.error.DocumentDoesNotExistException;
import com.couchbase.client.java.util.retry.RetryBuilder;
import com.folion.couchbase.service.BucketNotFoundException;
import com.google.gson.Gson;
import rx.Observable;
import rx.functions.Func1;

import java.util.Arrays;
import java.util.concurrent.TimeUnit;

public class CouchbaseActivityDao {

    private static CouchbaseActivityDao instance;

    private Gson gson;
    private Cluster cluster;
    private String bucketName;
    private Bucket bucket;

    public CouchbaseActivityDao(String[] clusters, String bucketName) {
        this.bucketName = bucketName;
        cluster = CouchbaseCluster.create(Arrays.asList(clusters));
        bucket = cluster.openBucket(bucketName, 1, TimeUnit.DAYS);
        gson = new Gson();
    }


    public static CouchbaseActivityDao getInstance() {
        if (instance == null) {
            String[] serverURIs = "http://localhost:8091".split(",");
            instance = new CouchbaseActivityDao(serverURIs, "geo");
        }
        return instance;
    }

    public void casUpdateJson(final String key, final Action action) {
        if (bucket == null) {
            throw new BucketNotFoundException("Bucket " + bucketName + " is not registered");
        }

        Observable
                .just(key)
                .flatMap(new Func1<String, Observable<RawJsonDocument>>() {
                    @Override
                    public Observable<RawJsonDocument> call(String id) {
                        System.out.println("get " + id);
                        return bucket.async().get(id, RawJsonDocument.class);
                    }
                })
                .map(new Func1<RawJsonDocument, RawJsonDocument>() {
                    @Override
                    public RawJsonDocument call(RawJsonDocument rawJsonDocument) {
                        System.out.println("update " + rawJsonDocument.content());

                        // modify your doc here
                        return rawJsonDocument;
                    }
                })
                .defaultIfEmpty(RawJsonDocument.create(key, gson.toJson(action)))
                .flatMap(new Func1<RawJsonDocument, Observable<?>>() {
                    @Override
                    public Observable<?> call(final RawJsonDocument rawJsonDocument) {
                        System.out.println("here");
                        return bucket.async().replace(rawJsonDocument)
                                // retry when CAS concurrent modifications quickly
                                .retryWhen(RetryBuilder.anyOf(CASMismatchException.class)
                                        .max(10).delay(Delay.fixed(10, TimeUnit.MICROSECONDS)).build())
                                .onErrorResumeNext(new Func1<Throwable, Observable<RawJsonDocument>>() {
                                    @Override
                                    public Observable<RawJsonDocument> call(Throwable throwable) {
                                        System.out.println("insert");
                                        // if doc does not exist on replace, fall back to insert
                                        if (throwable instanceof DocumentDoesNotExistException) {
                                            return bucket.async().insert(rawJsonDocument);
                                        }
                                        // if other error, forward it
                                        return Observable.error(throwable);
                                    }
                                });
                    }
                })
                .subscribe();


    }

    public void runTest() {
        Action action = new Action();
        action.setName("action-1");
        action.setType("action-type");
        CouchbaseActivityDao.getInstance().casUpdateJson("test", action);
    }

    public class Action {
        private String name;
        private String type;

        public void setName(String name) {
            this.name = name;
        }

        public void setType(String type) {
            this.type = type;
        }

        public String getName() {
            return name;
        }

        public String getType() {
            return type;
        }
    }

    public static void main(String arg[]) {
        CouchbaseActivityDao.getInstance().runTest();
    }


}