Boon Remix: How to Clone Collection in Java - Deep copy of ArrayList and HashSet with Boon

How to Clone Collection in Java - Deep copy of ArrayList and HashSet with Boon

Please visit and read this article. This is a remix of this: How to Clone Collection in Java - Deep copy of ArrayList and HashSet.

Boon has many utility methods to convert objects into maps, lists, JSON, etc. It also has many collection utility methods.

Programmer, none that I have ever met, have mistakenly used copy constructors by by various collection classes, as a way to clone Collection e.g. List, Set, ArrayList, HashSet or any other implementation. Or they write a lot of boiler plate code and spend a lot of time doing things to copy lists.

The key point is to remember is that the built-in collection lib does not do a deep copy.

If you have code using the original collection modifies an employee, that change could be reflected in the cloned collection. Similarly if an employee is modified in cloned collection, it will also appeared as modified in original collection.

This is less than desirable. A solution to avoid this problem is deep cloning of collection, which means recursively cloning object, until you reached to primitive or Immutable. But that takes a lot of work. Boon has an easier solution. Boon has a copy function that does a deep copy for you. In fact Boon has hundreds of such utility functions. Don't waste your time with cloning, use Boon and develop Java apps with a smile on your face.

deep copy using Set

        Set<Employee> original, copy;

        original = set(
                new Employee( "Joe", "Manager" ),
                new Employee( "Tim", "Developer" ),
                new Employee( "Frank", "Developer" ));

        copy = deepCopy( original );

        setCollectionProperty(original, "designation", "staff");


        puts("Original Set after modification", original);

        puts("Copy of Set after modification",  copy);

Output

Original Set after modification [Joe:staff, Tim:staff, Frank:staff] 
Copy of Set after modification [Joe:Manager, Tim:Developer, Frank:Developer] 

The above code is functionally equivalent to the article How to Clone Collection in Java - Deep copy of ArrayList and HashSet. But it is smaller and we did not have to implement the clone method. The deepCopy will even copy other properties which are instances of other domain objects even if those domain objects are in lists or arrays.

deep copy using List

        List<Employee> original, copy;

        original = list(
                new Employee("Joe", "Manager"),
                new Employee("Tim", "Developer"),
                new Employee("Frank", "Developer"));

        copy = deepCopy( original );

        setCollectionProperty(original, "designation", "staff");

Original List after modification [Joe:staff, Tim:staff, Frank:staff] 
Copy of List after modification [Joe:Manager, Tim:Developer, Frank:Developer] 

This just scratches the surface of what Boon can do.

Stop by the Boon wiki. Book Wiki

/*
 * Copyright 2013-2014 Richard M. Hightower
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *          http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * __________                              _____          __   .__
 * \______   \ ____   ____   ____   /\    /     \ _____  |  | _|__| ____    ____
 *  |    |  _//  _ \ /  _ \ /    \  \/   /  \ /  \\__  \ |  |/ /  |/    \  / ___\
 *  |    |   (  <_> |  <_> )   |  \ /\  /    Y    \/ __ \|    <|  |   |  \/ /_/  >
 *  |______  /\____/ \____/|___|  / \/  \____|__  (____  /__|_ \__|___|  /\___  /
 *         \/                   \/              \/     \/     \/       \//_____/
 *      ____.                     ___________   _____    ______________.___.
 *     |    |____ ___  _______    \_   _____/  /  _  \  /   _____/\__  |   |
 *     |    \__  \\  \/ /\__  \    |    __)_  /  /_\  \ \_____  \  /   |   |
 * /\__|    |/ __ \\   /  / __ \_  |        \/    |    \/        \ \____   |
 * \________(____  /\_/  (____  / /_______  /\____|__  /_______  / / ______|
 *               \/           \/          \/         \/        \/  \/
 */

package com.examples;

import org.junit.Test;

import java.util.List;
import java.util.Set;

import static org.boon.Boon.puts;
import static org.boon.Ok.okOrDie;
import static org.boon.Sets.deepCopy;
import static org.boon.Sets.set;
import static org.boon.Lists.list;
import static org.boon.Lists.deepCopy;
import static org.boon.Str.add;
import static org.boon.core.reflection.BeanUtils.setCollectionProperty;
import static org.boon.core.reflection.BeanUtils.copy;

public class DeepCopyRemix {



    public static class Employee {
        private String name;
        private String designation;

        public Employee(String name, String designation) {
            this.name = name;
            this.designation = designation;
        }

        public String getName() {
            return name;
        }

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

        public String getDesignation() {
            return designation;
        }

        public void setDesignation(String designation) {
            this.designation = designation;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Employee employee = (Employee) o;

            if (designation != null ? !designation.equals(employee.designation) : employee.designation != null)
                return false;
            if (name != null ? !name.equals(employee.name) : employee.name != null) return false;

            return true;
        }

        @Override
        public int hashCode() {
            int result = name != null ? name.hashCode() : 0;
            result = 31 * result + (designation != null ? designation.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return add(name, ":", designation);
        }
    }



    public static void main2 (String... args) {

        Set<Employee> original, copy;

        original = set(
                new Employee( "Joe", "Manager" ),
                new Employee( "Tim", "Developer" ),
                new Employee( "Frank", "Developer" ));

        copy = deepCopy( original );

        setCollectionProperty(original, "designation", "staff");


        puts("Original Set after modification", original);

        puts("Copy of Set after modification",  copy);




        Employee employee = new Employee("Joe", "Manager");
        Employee copyEmployee = copy(employee);


        okOrDie("not same object", employee != copyEmployee);

        okOrDie("not same object", copy.iterator().next() != original.iterator().next());
    }


    public static void main (String... args) {

        List<Employee> original, copy;

        original = list(
                new Employee("Joe", "Manager"),
                new Employee("Tim", "Developer"),
                new Employee("Frank", "Developer"));

        copy = deepCopy( original );

        setCollectionProperty(original, "designation", "staff");

        original.iterator().next().setDesignation("staff");

        puts("Original List after modification", original);

        puts("Copy of List after modification",  copy);

        okOrDie("not same object", copy.iterator().next() != original.iterator().next());


    }


    @Test
    public void test() {
        DeepCopyRemix.main();

        DeepCopyRemix.main2();
    }


}

Boon. Code Java with pleasure.

Thoughts

Thoughts? Write me at richard high tower AT g mail dot c-o-m (Rick Hightower).

Further Reading:

If you are new to boon start here:

• Java Boon Byte Buffer Builder
• Java Boon Slice Notation
• Java Boon Slice's work with TreeSets
• Java Boon Description
• More...
• Boon Home
• Boon Source
• Introducing Boon October 2013
• Java Slice Notation
• What if Java collections were easy to search and sort?
• Boon HTTP utils
• Boon Java JSON parser Benchmarks or hell yeah JSON parsing is damn fast!
• Boon JSON parser is really damn fast! Part II
• Boon JSON parser Round III now just not fast as but much faster than other Java JSON parsers
• Boon World's fastest Java JSON parser Round IV from fast to blazing to rocket fuel aka Braggers going to brag
• Boon gets adopted by JSON Path as the default Java JSON parser
• Boon graphics showing just how fast Boon JSON parsing is - about 50% to 200% faster than the graphs shown here now so wicked fast became wickeder - just got sick of making graphics
• 10 minute guide to Boon JSON parsing after I added @JsonIgnore, @JsonProperty, @JsonView, @Exposes, etc.
• Hightower speaks to the master of Java JSON parsing, the king of speed The COW TOWN CODER!
• Boon provides easy Java objects from lists, from maps and from JSON.

Why Boon?

Easily read in files into lines or a giant string with one method call. Works with files, URLs, class-path, etc. Boon IO support will surprise you how easy it is. Boon has Slice notation for dealing with Strings, Lists, primitive arrays, Tree Maps, etc. If you are from Groovy land, Ruby land, Python land, or whatever land, and you have to use Java then Boon might give you some relief from API bloat. If you are like me, and you like to use Java, then Boon is for you too. Boon lets Java be Java, but adds the missing productive APIs from Python, Ruby, and Groovy. Boon may not be Ruby or Groovy, but its a real Boon to Java development.

Core Boon Philosophy

Core Boon will never have any dependencies. It will always be able to run as a single jar. This is not just NIH, but it is partly. My view of what Java needs is more inline with what Python, Ruby and Groovy provide. Boon is an addition on top of the JVM to make up the difference between the harder to use APIs that come with Java and the types of utilities that are built into Ruby, Python, PHP, Groovy etc. Boon is a Java centric view of those libs. The vision of Boon and the current implementation is really far apart.

Contact Info

blog|[twitter](https://twitter.com/RickHigh|[infoq]http://www.infoq.com/author/Rick-Hightower|[stackoverflow](http://stackoverflow.com/users/2876739/rickhigh)|[java lobby](http://java.dzone.com/users/rhightower)|Other | richard high tower AT g mail dot c-o-m (Rick Hightower)|work|cloud|nosql

Java Boon - Boon Data Repo using Indexed Collections for Java Beans, JSON and Maps like JDK 8 streams but faster

Boon Data Repo Indexed Collections and ETL for Java Beans, JSON, Maps

Boon Home | Boon Source | If you are new to boon, you might want to start here. Simple opinionated Java for the novice to expert level Java Programmer. Low Ceremony. High Productivity. A real boon to Java to developers!

Java Boon - Boon Data Repo using Indexed Collections for Java Beans, JSON and Maps

Many languages have sorting, slicing, dicing capabilities for Lists and Maps, and JSON. Boon adds this to Java.

Boon Data Repo is an in-memory query engine that can use high speed indexed collections for very fast in-memory queries. This brief tutorial will show you how to use Boon to query JSON, Java objects and Java maps. And also how to do ELT transforms with JSON, Java objects and Java Maps.

Let's create some data to search.

List of Java Bean instances to filter

    static List<Department> departmentsList = list(
            new Department("Engineering").add(
                    new Employee(1, 100, "Rick", "Hightower", "555-555-1000"),
                    new Employee(2, 200, "John", "Smith", "555-555-1215", "555-555-1214", "555-555-1213"),
                    new Employee(3, 300, "Drew", "Donaldson", "555-555-1216"),
                    new Employee(4, 400, "Nick", "LaySacky", "555-555-1217")

            ),
            new Department("HR").add(
                    new Employee(5, 100, "Dianna", "Hightower", "555-555-1218"),
                    new Employee(6, 200, "Derek", "Smith", "555-555-1219"),
                    new Employee(7, 300, "Tonya", "Donaldson", "555-555-1220"),
                    new Employee(8, 400, "Sue", "LaySacky", "555-555-9999")

            ), new Department("Manufacturing").add(),
            new Department("Sales").add(),
            new Department("Marketing").add()

    );

The above creates lists of departments with lists of employees. The full code listing is at the end of this tutorial.

Boon does not just work with Java instances, it also works with Java maps so let's use some Boon utilities to create the same data but in lists and maps as follows:

List of Java Maps to search

    static List<?> departmentObjects = list(
            map("name", "Engineering",
                    "employees", list(
                    map("id", 1, "salary", 100, "firstName", "Rick", "lastName", "Hightower",
                            "contactInfo", map("phoneNumbers",
                            list("555-555-0000")
                    )
                    ),
                    map("id", 2, "salary", 200, "firstName", "John", "lastName", "Smith",
                            "contactInfo", map("phoneNumbers", list("555-555-1215",
                            "555-555-1214", "555-555-1213"))),
                    map("id", 3, "salary", 300, "firstName", "Drew", "lastName", "Donaldson",
                            "contactInfo", map("phoneNumbers", list("555-555-1216"))),
                    map("id", 4, "salary", 400, "firstName", "Nick", "lastName", "LaySacky",
                            "contactInfo", map("phoneNumbers", list("555-555-1217")))

            )
            ),
            map("name", "HR",
                    "employees", list(
                    map("id", 5, "salary", 100, "departmentName", "HR",
                            "firstName", "Dianna", "lastName", "Hightower",
                            "contactInfo",
                            map("phoneNumbers", list("555-555-1218"))),
                    map("id", 6, "salary", 200, "departmentName", "HR",
                            "firstName", "Derek", "lastName", "Smith",
                            "contactInfo",
                            map("phoneNumbers", list("555-555-1219"))),
                    map("id", 7, "salary", 300, "departmentName", "HR",
                            "firstName", "Tonya", "lastName", "Donaldson",
                            "contactInfo", map("phoneNumbers", list("555-555-1220"))),
                    map("id", 8, "salary", 400, "departmentName", "HR",
                            "firstName", "Sue", "lastName", "LaySacky",
                            "contactInfo", map("phoneNumbers", list("555-555-9999")))

            )
            ),
            map("name", "Manufacturing", "employees", Collections.EMPTY_LIST),
            map("name", "Sales", "employees", Collections.EMPTY_LIST),
            map("name", "Marketing", "employees", Collections.EMPTY_LIST)
    );

Next we are going to create a repo so we can easily search this list of Departments whit lists of Employees of the list of maps of lists of maps of lists.

Grab just the employees

        List<Employee> employees;



        /** Get all employees in every department. */
        employees = (List<Employee>) atIndex(departmentsList, "employees");

Bam! We have not really got to the data repo part, but did you just see that Boon Kung Fo! We just grabbed every employee from every department and pulled all of the employees into one list. We took a hierarchy and made it flat in just one line of code. BOOM! No?! Boon. Boon is full of these utility methods and I will write a whole tutorial on just those. But I digress....

Let's create our Data Repo which is a set of indexed collections as follows:

Description of code example one sentence

        Repo<Integer,Employee> employeeRepo;

        /** It builds indexes on properties. */
        employeeRepo = Repos.builder()
                .primaryKey("id")
                .searchIndex("department.name")
                .searchIndex("salary")
                .build(int.class, Employee.class).init(employees);

We setup a primary key on the field id (Boon can use fields or Java properties), we setup a search index on department name so we can search by department name really fast. And we setup a search index on salary. Then we told the Repo builder that our primary key is and int and we are going to manage classes.

Now let's start searching.

Searching the employee list with Boon

        List<Employee> results =
                employeeRepo.query(eq("department.name", "HR"));

        /* Verify. */
        Int.equalsOrDie(4, results.size());

        Str.equalsOrDie("HR", results.get(0).getDepartment().getName());

Boon Repo has search criteria like eq (equals), gt (greater than), between, and some you never dreamed of like searching objects based on type hierarchy, and all of it can use indexes, and after index searching the results down, it does the final criteria with filters so basically Boon does in-memory what a typical data base does. Boon Repo has a query engine. It is really fast.

Passing multiple criteria search by department name with salary above 301

        results = employeeRepo.query( eq("department.name", "HR"),
                gt("salary", 301));

        /* Verify. */
        Int.equalsOrDie(1, results.size());

        Str.equalsOrDie("HR", results.get(0).getDepartment().getName());

        Str.equalsOrDie("Sue", results.get(0).getFirstName());

Boon is happy to create indexes on Java objects, but it can also just work with lists of maps or even JSON.

Working with List/Maps

        List<Map<String, Object>> employeeMaps;

        Repo<Integer,Map<String, Object>> employeeMapRepo;


        /** Get all employees in every department. */
        employeeMaps = (List<Map<String, Object>>) atIndex(departmentObjects, "employees");


        /** It builds indexes on properties. */
        employeeMapRepo = (Repo<Integer,Map<String, Object>>) (Object)
                Repos.builder()
                        .primaryKey("id")
                        .searchIndex("departmentName")
                        .searchIndex("salary")
                        .build(int.class, Map.class).init((List)employeeMaps);

Now we can search just like before but now our domain objects so to speak are just maps and lists.

Searching against Maps and Lists

        List<Map<String, Object>> resultMaps =
                employeeMapRepo.query(eq("departmentName", "HR"));

Verifying that we found what we were looking for... Searching against Maps and Lists

        /* Verify. */
        Int.equalsOrDie(4, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));


        resultMaps = employeeMapRepo.query( eq("departmentName", "HR"),
                gt("salary", 301));

         /* Verify. */
        Int.equalsOrDie(1, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));

        Str.equalsOrDie("Sue", (String) resultMaps.get(0).get("firstName"));

Like was mentioned again. Boon also works directly against JSON as follows:

Searching JSON with Boon

        /** Now with JSON. */

        String json = toJson(departmentObjects);
        puts(json);

        List<?> array =  (List<?>) fromJson(json);
        employeeMaps =
                (List<Map<String, Object>>) atIndex(array, "employees");

        employeeMapRepo = (Repo<Integer,Map<String, Object>>) (Object)
                Repos.builder()
                        .primaryKey("id")
                        .searchIndex("departmentName")
                        .searchIndex("salary")
                        .build(int.class, Map.class).init((List)employeeMaps);


        resultMaps = employeeMapRepo.query(
                eq("departmentName", "HR"), gt("salary", 301));

Making sure we found the maps we were looking for

        /* Verify. */
        Int.equalsOrDie(1, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));

        Str.equalsOrDie("Sue", (String) resultMaps.get(0).get("firstName"));

Boon sorting, filtering and index searching can all use Boon's property path expression which works with Java object, java.util.Map, and you guessed it JSON.

Here is an example of an ETL transform to converts one list into another.

JSON ETL Transform with Boon

        List<Map<String, Object>> list = employeeMapRepo.query(
                selects(
                        selectAs("firstName", "fn"),
                        selectAs("lastName", "ln"),
                        selectAs("contactInfo.phoneNumbers[0]", "ph"),

                        selectAs("salary", "pay", new Function<Integer, Float>() {
                            @Override
                            public Float apply(Integer salary) {
                                float pay = salary.floatValue() / 100;
                                return pay;
                            }
                        })
                )
        );

        puts (toJson(list));

The above turns this JSON:

[{"name":"Engineering","employees":[{"id":1,"salary":100,"firstName":"Rick","lastName":"Hightower","contactInfo":{"phoneNumbers":["555-555-0000"]}}

Into This JSON:

{"fn":"Rick","ln":"Hightower","ph":"555-555-0000","pay":1.0}

Now keep in mind that this works with JSON, Java Instances and Maps. So you pick and it can transform from one to the other and back. What about munging stuff together and calling other functions to do transforms, and what not... You know... so real nasty ETL! Boon does nasty ETL.

Nasty ETL with Boon

        template = template();
        template.addFunctions(new DecryptionService());

        template.addFunctions(new Salary());



        list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "{{firstName}} {{lastName}}",
                                template),
                        selectAs("contactInfo.phoneNumbers[0]", "ph"),
                        selectAsTemplate("pay", "{{pay(salary)}}", template),
                        selectAsTemplate("id", "{{DecryptionService.decrypt(id)}}", template)

                )
        );

        puts (list);

Notice that this uses templates to do concatenation, it uses path expressions, and calls methods from the DecryptionService and the Salary (pay()), which are just pretend services that I made up for this example.

Boon also has a few template engines built in which makes data munging a bit easier.

Now we have this pretty JSON:

{"fullName":"Rick Hightower", ph:"555-555-0000", pay:1.0, id:49}

Boon has easy ways to turn maps into objects so it is child's play to convert the list of maps into a list of object. Remember all of the selection business works with JSON, Java instances and Java HashMaps.

Of course the above is a query so you can add a select clause to filter out objects and such. I am trying not to drown you in detail, but it is easy to manipulate the objects to/fro JSON/Maps/Java instance. Flick of the wrist!

Also if you hate handlebars, there is a JSTL syntax so let's show that.

Just like last example but we use JSTL instead of handlebar syntax

        template = jstl();
        template.addFunctions(new DecryptionService());
        template.addFunctions(new Salary());



        list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "${lastName},${firstName}",
                                template),
                        selectAsTemplate("ph", "${contactInfo.phoneNumbers[0]}",
                                template),
                        selectAsTemplate("pay", "${pay(salary)}", template),
                        selectAsTemplate("id", "${DecryptionService.decrypt(id)}", template)

                )
        );

        puts (list);

Which begets…

{"fullName":"Hightower,Rick", "ph":"555-555-0000", pay:1.0, id:49}

I forgot to show of the where clause so let's see it again.

list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "${lastName},${firstName}",
                                template),
                        selectAsTemplate("ph", "${contactInfo.phoneNumbers[0]}",
                                template),
                        selectAsTemplate("pay", "${pay(salary)}", template),
                        selectAsTemplate("id", "${DecryptionService.decrypt(id)}", template)

                ), gt("salary", 50), eq("firstName", "Rick")
        );

Now we have this.

[{fullName=Hightower,Rick, ph=555-555-0000, pay=1.0, id=49}] 

The criteria can have complex path expressions (see ${contactInfo.phoneNumbers[0]). We have just scratched the service of what Boon can do. Boon can slice, dice, transform, and search Java objects 50 ways to Sunday.

To read more about Boon sorting and searching capabilities please read.

• Boon high-speed sorting for JSON and Java objects

In addition to linear searching as you saw above, Boon has the ability to run indexed searches as well as ETL transforms for Java and JSON objects in memory.

• Boon Data Repo Indexed Collections and ETL for Java Beans, JSON, Maps

Much of Boon's sorting, index searching, ETL, and so on came out of Boon's Data Repo, which provides the indexed search capabilities. You can churn through millions of objects in memory in mere moments with indexed collections.

• Boon Data Repo step by step

You also want to read about Boon's path expressions.

• Boon Path Expressions which get used by sorting, filtering and indexed collection searches

Boon's DataRepo allows you to treat Java collections more like a database. DataRepo is not an in memory database, and cannot substitute arranging your objects into data structures optimized for your application.

If you want to spend your time providing customer value and building your objects and classes and using the Collections API for your data structures, then Boon DataRepo is meant for you. This does not preclude breaking out the Knuth books and coming up with an optimized data structure. It just helps keep the mundane things easy and so you can spend your time making the hard things possible.

This project came out of a need. I was working on a project that planned to store large collection of domain objects in memory for speed, and somebody asked an all to important question that I overlooked. How are we going to query this data. My answer was we will use the Collections API and the Streaming API. Then I tried to do this...

I tired using the JDK 8 stream API on a large data set, and it was slow. It was a linear search/filter. This is by design, but for what I was doing, it did not work. I needed indexes to support arbitrary queries, and out came Boon Data Repo.

Boon's data repo augments the streaming API and provides a indexed collection search and many other utilities around searching, filtering and transforming Java class instances, Maps, and JSON.

Boon's DataRepo does not endeavor to replace the JDK 8 stream API, and in fact it works well with it. By design, Boon DataRepo works with standard collection libraries.

Boon's data repo makes doing index based queries on collections a lot easier.

It provides a simplified API for doing so.

You can use a wrapper class to wrap a collection into a indexed collection.

Let's say you have a method that creates 200,000 employee objects like this:

        List<Employee> employees = TestHelper.createMetricTonOfEmployees(200_000);

So now we have 200,000 employees. Let's search them...

First wrap Employees in a searchable query:

        employees = query(employees);

Now search:

        List<Employee> results = query(employees, eq("firstName", firstName));

So what is the main difference between the above and the stream API?

        employees.stream().filter(emp -> emp.getFirstName().equals(firstName)

About a factor of 20,000% faster to use Boon DataRepo!

There is an API that looks just like your built-in collections. There is also an API that looks more like a DAO object or a Repo Object.

A simple query with the Repo/DAO object looks like this:

        List<Employee> employees = repo.query(eq("firstName", "Diana"));

A more involved query would look like this:

        List<Employee> employees = repo.query(
                and(eq("firstName", "Diana"), eq("lastName", "Smith"), eq("ssn", "21785999")));

Or this:

        List<Employee> employees = repo.query(
                and(startsWith("firstName", "Bob"), eq("lastName", "Smith"), lte("salary", 200_000),
                        gte("salary", 190_000)));

Or this:

        List<Employee> employees = repo.query(
                and(startsWith("firstName", "Bob"), eq("lastName", "Smith"), between("salary", 190_000, 200_000)));

Or if you want to use JDK 8 stream API, this works with it not against it:

        int sum = repo.query(eq("lastName", "Smith")).stream().filter(emp -> emp.getSalary()>50_000)
                .mapToInt(b -> b.getSalary())
                .sum();

The above would be much faster if the number of employees was quite large. It would narrow down the employees whose name started with Smith and had a salary above 50,000. Let's say you had 100,000 employees and only 50 named Smith so now you narrow to 50 quickly by using the TreeMap which effectively pulls 50 employees out of 100_000, then we do the filter over just 50 instead of the whole 100,000.

To learn more about the Boon Data Repo go here:

• Java Boon Data Repo

Complete example from above

/*
 * Copyright 2013-2014 Richard M. Hightower
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *          http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * __________                              _____          __   .__
 * \______   \ ____   ____   ____   /\    /     \ _____  |  | _|__| ____    ____
 *  |    |  _//  _ \ /  _ \ /    \  \/   /  \ /  \\__  \ |  |/ /  |/    \  / ___\
 *  |    |   (  <_> |  <_> )   |  \ /\  /    Y    \/ __ \|    <|  |   |  \/ /_/  >
 *  |______  /\____/ \____/|___|  / \/  \____|__  (____  /__|_ \__|___|  /\___  /
 *         \/                   \/              \/     \/     \/       \//_____/
 *      ____.                     ___________   _____    ______________.___.
 *     |    |____ ___  _______    \_   _____/  /  _  \  /   _____/\__  |   |
 *     |    \__  \\  \/ /\__  \    |    __)_  /  /_\  \ \_____  \  /   |   |
 * /\__|    |/ __ \\   /  / __ \_  |        \/    |    \/        \ \____   |
 * \________(____  /\_/  (____  / /_______  /\____|__  /_______  / / ______|
 *               \/           \/          \/         \/        \/  \/
 */

package com.examples;

import org.boon.core.Function;
import org.boon.datarepo.Repo;
import org.boon.datarepo.Repos;
import  org.boon.primitive.Int;

import org.boon.Lists;
import org.boon.Str;
import org.boon.criteria.ObjectFilter;
import org.boon.template.BoonTemplate;
import org.junit.Test;

import java.util.Collections;
import java.util.List;
import java.util.Map;

import static org.boon.Boon.fromJson;
import static org.boon.Boon.puts;
import static org.boon.Boon.toJson;
import static org.boon.Lists.copy;
import static org.boon.Lists.lazyAdd;
import static org.boon.Lists.list;
import static org.boon.Maps.map;
import static org.boon.core.reflection.BeanUtils.atIndex;
import static org.boon.criteria.ObjectFilter.*;
import static org.boon.criteria.Selector.selectAs;
import static org.boon.criteria.Selector.selectAsTemplate;
import static org.boon.criteria.Selector.selects;
import static org.boon.template.BoonTemplate.jstl;
import static org.boon.template.BoonTemplate.template;

public class DataRepoExample {

    static boolean ok;


    public static void main(String... args) {

        List<Employee> employees;

        Repo<Integer,Employee> employeeRepo;


        /** Get all employees in every department. */
        employees = (List<Employee>) atIndex(departmentsList, "employees");


        /** It builds indexes on properties. */
        employeeRepo = Repos.builder()
                .primaryKey("id")
                .searchIndex("department.name")
                .searchIndex("salary")
                .build(int.class, Employee.class).init(employees);

        List<Employee> results =
                employeeRepo.query(eq("department.name", "HR"));

        /* Verify. */
        Int.equalsOrDie(4, results.size());

        Str.equalsOrDie("HR", results.get(0).getDepartment().getName());


        results = employeeRepo.query( eq("department.name", "HR"),
                gt("salary", 301));

        /* Verify. */
        Int.equalsOrDie(1, results.size());

        Str.equalsOrDie("HR", results.get(0).getDepartment().getName());

        Str.equalsOrDie("Sue", results.get(0).getFirstName());




        List<Map<String, Object>> employeeMaps;

        Repo<Integer,Map<String, Object>> employeeMapRepo;


        /** Get all employees in every department. */
        employeeMaps = (List<Map<String, Object>>) atIndex(departmentObjects, "employees");


        /** It builds indexes on properties. */
        employeeMapRepo = (Repo<Integer,Map<String, Object>>) (Object)
                Repos.builder()
                        .primaryKey("id")
                        .searchIndex("departmentName")
                        .searchIndex("salary")
                        .build(int.class, Map.class).init((List)employeeMaps);


        List<Map<String, Object>> resultMaps =
                employeeMapRepo.query(eq("departmentName", "HR"));

        /* Verify. */
        Int.equalsOrDie(4, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));


        resultMaps = employeeMapRepo.query( eq("departmentName", "HR"),
                gt("salary", 301));

         /* Verify. */
        Int.equalsOrDie(1, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));

        Str.equalsOrDie("Sue", (String) resultMaps.get(0).get("firstName"));




        /** Now with JSON. */

        String json = toJson(departmentObjects);
        puts(json);

        List<?> array =  (List<?>) fromJson(json);
        employeeMaps =
                (List<Map<String, Object>>) atIndex(array, "employees");

        employeeMapRepo = (Repo<Integer,Map<String, Object>>) (Object)
                Repos.builder()
                        .primaryKey("id")
                        .searchIndex("departmentName")
                        .searchIndex("salary")
                        .build(int.class, Map.class).init((List)employeeMaps);


        resultMaps = employeeMapRepo.query(
                eq("departmentName", "HR"), gt("salary", 301));



        /* Verify. */
        Int.equalsOrDie(1, resultMaps.size());

        Str.equalsOrDie("HR", (String) resultMaps.get(0).get("departmentName"));

        Str.equalsOrDie("Sue", (String) resultMaps.get(0).get("firstName"));


        List<Map<String, Object>> list = employeeMapRepo.query(
                selects(
                        selectAs("firstName", "fn"),
                        selectAs("lastName", "ln"),
                        selectAs("contactInfo.phoneNumbers[0]", "ph"),

                        selectAs("salary", "pay", new Function<Integer, Float>() {
                            @Override
                            public Float apply(Integer salary) {
                                float pay = salary.floatValue() / 100;
                                return pay;
                            }
                        })
                )
        );

        puts (toJson(list));




        BoonTemplate template = template();
        template.addFunctions(new DecryptionService());

        template.addFunctions(new Salary());



        list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "{{firstName}} {{lastName}}",
                                template),
                        selectAs("contactInfo.phoneNumbers[0]", "ph"),
                        selectAsTemplate("pay", "{{pay(salary)}}", template),
                        selectAsTemplate("id", "{{DecryptionService.decrypt(id)}}", template)

                )
        );

        puts (list);


        template = jstl();
        template.addFunctions(new DecryptionService());
        template.addFunctions(new Salary());



        list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "${lastName},${firstName}",
                                template),
                        selectAsTemplate("ph", "${contactInfo.phoneNumbers[0]}",
                                template),
                        selectAsTemplate("pay", "${pay(salary)}", template),
                        selectAsTemplate("id", "${DecryptionService.decrypt(id)}", template)

                )
        );

        puts (list);


        template = jstl();
        template.addFunctions(new DecryptionService());
        template.addFunctions(new Salary());



        list = employeeMapRepo.query(
                selects(
                        selectAsTemplate("fullName", "${lastName},${firstName}",
                                template),
                        selectAsTemplate("ph", "${contactInfo.phoneNumbers[0]}",
                                template),
                        selectAsTemplate("pay", "${pay(salary)}", template),
                        selectAsTemplate("id", "${DecryptionService.decrypt(id)}", template)

                ), gt("salary", 50), eq("firstName", "Rick")
        );


        puts (list);

    }

    public static class DecryptionService {
        public String decrypt(Integer id) {
            return "" + ("" + (id == null ? "null" :  id.hashCode())).hashCode();
        }
    }

    public static class Salary {
        public Float pay(Integer salary) {
            float pay = salary.floatValue() / 100;
            return pay;
        }

    }


    @Test
    public void test() {
        DataRepoExample.main();

    }

    public static class ContactInfo {
        String address;
        List<String> phoneNumbers;


    }

    public static class Employee implements Comparable<Employee> {
        int id;
        int salary;
        String firstName;
        String lastName;

        ContactInfo contactInfo = new ContactInfo();
        Department department;

        public Employee() {
        }

        public Employee(int id, int salary, String firstName, String lastName,
                        String... phoneNumbers) {
            this.id = id;
            this.salary = salary;
            this.firstName = firstName;
            this.lastName = lastName;

            for (String phone : phoneNumbers) {
                contactInfo.phoneNumbers = lazyAdd(contactInfo.phoneNumbers, phone);
            }
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public int getSalary() {
            return salary;
        }

        public void setSalary(int salary) {
            this.salary = salary;
        }

        public String getFirstName() {
            return firstName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        public Department getDepartment() {
            return department;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Employee employee = (Employee) o;

            if (id != employee.id) return false;
            if (salary != employee.salary) return false;
            if (firstName != null ? !firstName.equals(employee.firstName) : employee.firstName != null) return false;
            if (lastName != null ? !lastName.equals(employee.lastName) : employee.lastName != null) return false;

            return true;
        }

        @Override
        public int hashCode() {
            int result = id;
            result = 31 * result + salary;
            result = 31 * result + (firstName != null ? firstName.hashCode() : 0);
            result = 31 * result + (lastName != null ? lastName.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Employee{" +
                    "id=" + id +
                    ", salary=" + salary +
                    ", department=" + (department == null ? "NONE" : department.getName()) +
                    ", phone number=" + atIndex(this, "contactInfo.phoneNumbers[0]") +
                    ", firstName='" + firstName + '\'' +
                    ", lastName='" + lastName + '\'' +
                    "}";
        }

        @Override
        public int compareTo(Employee otherEmployee) {
            return this.firstName.compareTo(otherEmployee.firstName);
        }

        public void setDepartment(Department department) {
            this.department =  department;
        }
    }

    public static class Department {
        private String name;

        private List<Employee> employees;

        public Department() {
        }

        public Department(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

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

        public Department add(Employee... employees) {

            for (Employee employee : employees) {
                employee.setDepartment(this);
            }
            this.employees = lazyAdd(this.employees, employees);
            return this;
        }


        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Department that = (Department) o;

            if (employees != null ? !employees.equals(that.employees) : that.employees != null) return false;
            if (name != null ? !name.equals(that.name) : that.name != null) return false;

            return true;
        }

        @Override
        public int hashCode() {
            int result = name != null ? name.hashCode() : 0;
            result = 31 * result + (employees != null ? employees.hashCode() : 0);
            return result;
        }

        @Override
        public String toString() {
            return "Department{" +
                    "name='" + name + '\'' +
                    ", employees=" + atIndex(employees, "id") +
                    '}';
        }
    }


    static List<Department> departmentsList = list(
            new Department("Engineering").add(
                    new Employee(1, 100, "Rick", "Hightower", "555-555-1000"),
                    new Employee(2, 200, "John", "Smith", "555-555-1215", "555-555-1214", "555-555-1213"),
                    new Employee(3, 300, "Drew", "Donaldson", "555-555-1216"),
                    new Employee(4, 400, "Nick", "LaySacky", "555-555-1217")

            ),
            new Department("HR").add(
                    new Employee(5, 100, "Dianna", "Hightower", "555-555-1218"),
                    new Employee(6, 200, "Derek", "Smith", "555-555-1219"),
                    new Employee(7, 300, "Tonya", "Donaldson", "555-555-1220"),
                    new Employee(8, 400, "Sue", "LaySacky", "555-555-9999")

            ), new Department("Manufacturing").add(),
            new Department("Sales").add(),
            new Department("Marketing").add()

    );

    static List<?> departmentObjects = list(
            map("name", "Engineering",
                    "employees", list(
                    map("id", 1, "salary", 100, "firstName", "Rick", "lastName", "Hightower",
                            "contactInfo", map("phoneNumbers",
                            list("555-555-0000")
                    )
                    ),
                    map("id", 2, "salary", 200, "firstName", "John", "lastName", "Smith",
                            "contactInfo", map("phoneNumbers", list("555-555-1215",
                            "555-555-1214", "555-555-1213"))),
                    map("id", 3, "salary", 300, "firstName", "Drew", "lastName", "Donaldson",
                            "contactInfo", map("phoneNumbers", list("555-555-1216"))),
                    map("id", 4, "salary", 400, "firstName", "Nick", "lastName", "LaySacky",
                            "contactInfo", map("phoneNumbers", list("555-555-1217")))

            )
            ),
            map("name", "HR",
                    "employees", list(
                    map("id", 5, "salary", 100, "departmentName", "HR",
                            "firstName", "Dianna", "lastName", "Hightower",
                            "contactInfo",
                            map("phoneNumbers", list("555-555-1218"))),
                    map("id", 6, "salary", 200, "departmentName", "HR",
                            "firstName", "Derek", "lastName", "Smith",
                            "contactInfo",
                            map("phoneNumbers", list("555-555-1219"))),
                    map("id", 7, "salary", 300, "departmentName", "HR",
                            "firstName", "Tonya", "lastName", "Donaldson",
                            "contactInfo", map("phoneNumbers", list("555-555-1220"))),
                    map("id", 8, "salary", 400, "departmentName", "HR",
                            "firstName", "Sue", "lastName", "LaySacky",
                            "contactInfo", map("phoneNumbers", list("555-555-9999")))

            )
            ),
            map("name", "Manufacturing", "employees", Collections.EMPTY_LIST),
            map("name", "Sales", "employees", Collections.EMPTY_LIST),
            map("name", "Marketing", "employees", Collections.EMPTY_LIST)
    );



}

Thoughts

Thoughts? Write me at richard high tower AT g mail dot c-o-m (Rick Hightower).

Further Reading:

If you are new to boon start here:

• Java Boon Byte Buffer Builder
• Java Boon Slice Notation
• Java Boon Slice's work with TreeSets
• Java Boon Description
• More...
• Boon Home
• Boon Source
• Introducing Boon October 2013
• Java Slice Notation
• What if Java collections were easy to search and sort?
• Boon HTTP utils
• Boon Java JSON parser Benchmarks or hell yeah JSON parsing is damn fast!
• Boon JSON parser is really damn fast! Part II
• Boon JSON parser Round III now just not fast as but much faster than other Java JSON parsers
• Boon World's fastest Java JSON parser Round IV from fast to blazing to rocket fuel aka Braggers going to brag
• Boon gets adopted by JSON Path as the default Java JSON parser
• Boon graphics showing just how fast Boon JSON parsing is - about 50% to 200% faster than the graphs shown here now so wicked fast became wickeder - just got sick of making graphics
• 10 minute guide to Boon JSON parsing after I added @JsonIgnore, @JsonProperty, @JsonView, @Exposes, etc.
• Hightower speaks to the master of Java JSON parsing, the king of speed The COW TOWN CODER!
• Boon provides easy Java objects from lists, from maps and from JSON.

Why Boon?

Easily read in files into lines or a giant string with one method call. Works with files, URLs, class-path, etc. Boon IO support will surprise you how easy it is. Boon has Slice notation for dealing with Strings, Lists, primitive arrays, Tree Maps, etc. If you are from Groovy land, Ruby land, Python land, or whatever land, and you have to use Java then Boon might give you some relief from API bloat. If you are like me, and you like to use Java, then Boon is for you too. Boon lets Java be Java, but adds the missing productive APIs from Python, Ruby, and Groovy. Boon may not be Ruby or Groovy, but its a real Boon to Java development.

Core Boon Philosophy

Core Boon will never have any dependencies. It will always be able to run as a single jar. This is not just NIH, but it is partly. My view of what Java needs is more inline with what Python, Ruby and Groovy provide. Boon is an addition on top of the JVM to make up the difference between the harder to use APIs that come with Java and the types of utilities that are built into Ruby, Python, PHP, Groovy etc. Boon is a Java centric view of those libs. The vision of Boon and the current implementation is really far apart.

Contact Info

blog|[twitter](https://twitter.com/RickHigh|[infoq]http://www.infoq.com/author/Rick-Hightower|[stackoverflow](http://stackoverflow.com/users/2876739/rickhigh)|[java lobby](http://java.dzone.com/users/rhightower)|Other | richard high tower AT g mail dot c-o-m (Rick Hightower)|work|cloud|nosql