Hire Top Freelance Java developers with Ultragenius

Ultragenius is a marketplace for top software developers, engineers, programmers, coders, architects, and consultants. Top start-ups and companies choose developers from Ultragenius platform for their critical software projects. Hire from Ultragenius network & scale your engineering team in a matter of few days. 

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Hire only the top 1% among the 20K+ engineers who have applied to Ultragenius

Rishabh

Senior Java Developer

Rishabh is a software engineer having 7+ years of experience in developing server-side web applications. He has majorly worked in Big data and Android development.

Expert in

Java

Kotlin

Scala

Python

Experience

10 Years

Availability

Full Time

Mahesh

Remote Java Developer

Mahesh is a remote Java developer having 7+ years of experience working on backend development projects and developing microservices in Java.

Expert in

Java

SQL

C++

Spring

Experience

10 Years

Availability

Full Time

John

Fully Remote Java Developer

John is a software engineer having 10+ years of experience developing server-side applications and has majorly worked in system design and developing service-oriented architecture .

Expert in

Java

REST-APIs

CSS

HTML

Experience

10 Years

Availability

Full Time

Hire top freelance Java developers with Ultragenius

Java is one of the widely used object-oriented programming language designed to have as minimum implementation dependencies as possible in an application. Java is an evergreen language used on both client-side and server-side.

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01
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We’ll schedule a call and understand your requirements.

02
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Get the list of pre-vetted candidates in days.

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We will arrange a call after understanding your requirements.

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Start working with Ultragenius with a 1-week trial period.

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Ultragenius offers a great opportunity to work in mission-driven U.S. companies with a great salary. I am glad that I chose Ultragenius to find my dream job.
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Remote Java Developer
Once you are part of Ultragenius, you don't have to look for another platform which leads you to your dream job. Ultragenius's vetting tests and assessments are unmatchable and helped me a land an excellent job.
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Senior Java Developer Remote
I will thank to Ultragenius wholeheartedly. It helped me securing a career-growing high paid job which I couldn't think would be possible for me without this top connecting network.
Mark Sommers
Freelance Java Developer

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Want to hire freelance Java developers on your own? Here are the skills you must look for while hiring a remote Java developer

Hiring freelance Java developers might be a complex task for you if you are a non-technical manager. Java is an evergreen programming language used for developing both client-side and server-side applications and its flexibility to get used in Android development makes it one of the highest demanding skills of the 21st century. But, here comes the challenge, how to hire the most suitable freelance Java developers who exactly match your job applications. No worries, Ultragenius comes to assist you while recruiting the top skilled freelance Java developers on your own. Ultragenius understands your job requirements and gets you only the proficient freelance Java developers who have in-depth knowledge in developing software applications.

The following skills you must look while recruiting a freelance Java developer – 

Strong understanding of Object-Oriented Programming Skills (OOPS)-

Object-Oriented Programming is one of the most essential skills of a Java developer. To develop real-world applications, binding data members and functions are mostly required and to achieve loose coupling among the classes.

  • Encapsulation – Encapsulation is binding the related data members or variables and functions inside a single unit called class. This mechanism prevents the code from accessing outside a particular class. Encapsulation is achieved by declaring the variables of a class as private and using the getter() and setter() methods to access them indirectly ensuring security.
  • Inheritance – Inheritance is one of the widely used concepts in real-world programming that allows one class to extend the functionality of other classes and use its member functions instead of writing again multiple lines of code.
  • Abstraction – Abstraction is required when we have to define a parent class that contains only the structure of a given project and the implementation has to be done by its child class. Abstraction is the mechanism of hiding the data implementation and showing only the necessary details.
  • Polymorphism – Polymorphism allows an object to behave differently on its invocation. There are two types  – Compile-time Polymorphism and Run-time Polymorphism. 

In Compile-time Polymorphism, the methods with the same name behave differently according to the number of arguments and return type. 

For example, 

int mul (int a, int b) {

 return a*b;

}

double mul (double a, double b){ 

return a*b;

}

In Run-time Polymorphism, the overridden method is invoked by the parent class reference and it determines which method to call based on the object created. 

class Bike{ 

void run(){

System.out.println(“running…”);

}

} class Bajaj extends Bike{ 

void run(){

System.out.println(“running safely with the avg. speed of 20km/hr”);

}

}

public static void main( String[] args ){

Bike bike = new Bajaj();

bike.run();

Output is  –  running safely with the avg. speed of 20km/hr.

Besides these four concepts, the freelance Java developer must also know about Composition, Association, and Aggregation. 

Familiarity with the core HTML, CSS, and Javascript

To develop a full-stack applications in Java,  the knowldege of HTML, CSS, and Javascript is required in designing an excellent User Interface (UI). The developer must know more than one Javascript library framework like jQuery, Bootstrap and must be specialized in working with Asynchronous Javascript and XML (AJAX). Check if the developers have worked with Javascript build tools such as Grunt.js, Gulp.js, and Bower.js.

Experienced implementing Design Patterns in Java
  • Experience implementing Design Patterns in Java


It is a must-required skill for any Java developer to know about the design patterns and utilize them in developing system architecture. Every design pattern is a blueprint. Here are the important design patterns every developer should know –
Creational Design Pattern, Structural Design Pattern, Behavioral Design Pattern, JEE Design Pattern.
 


Creational Design Patterns are mainly concerned with the process of creating objects.

Structural Design Patterns are responsible for composing classes and objects which form larger structures.

Behaviour Design Patterns are responsible for establishing interaction between objects.

JEE Design Patterns are responsible for providing solutions to Java Enterprise Edition-based software applications.
 

  • Creational Design Patterns are Singleton Design Pattern, Builder Pattern,  Factory Method, Abstract Factory, and Prototype Pattern.
  • Structural Design Patterns are Adapter, Bridge, Composite, Facade, Flyweight, Proxy.
  • Behavioral Patterns are Command, Mediator, Iterator, Chain of Responsibility,  Observer, Memento, Template Method, Observer, State, Strategy, and Visitor. 


The Java developer must also be familiar with – Layered Pattern, Client-server Pattern, Master-slave Pattern, Pipe-filter Pattern, Peer-to-Peer Pattern, Broker Pattern, Event-bus Pattern, Model-View-Controller Pattern, Blackboard Pattern, and Interpreter Pattern.

Strong understanding of SOLID Principles -

Understanding SOLID principles is the core skill required for any Java developer. Java is designed to reduce dependencies among classes so that software engineers can work in modules easily and change one part of software without affecting the other. SOLID stands for – Single Responsibility Principle, Open/Closed Principle, Liskov Substitution Principle, Interface Segregation Principle, and Dependency Inversion Principle. 



Single Responsibility  – Each class is responsible only for one thing and serves only one part of the software’s functionality. It ensures loose coupling by limiting the scope of classes.


Open/Closed Principle – Classes, functions, and modules are open for extension, but close for modification. This means new functionality can be added in a class but it must not modify the existing code.


Liskov Substitution Principle – Every derived class should be substitutable for its base class. The subclass can replace the base class and must keep the program behavior unchanged.


Interface Segregation Principle –  A class should not be forced to implement an interface that it does not use.


Dependency Inversion Principle – The classes should depend upon abstract classes or interfaces instead of directly implementing concrete classes or functions.

 

Proficient using Microservices -

Microservices is a well-known software design architecture designed to overcome the disadvantage of traditional monolithic architecture. Loose coupling in software development is achieved with the microservices which break a large software application into smaller, independent, and loosely coupled modules on which various developers in a team can work separately. 

Advantages of Microservices – 

  • Failure of a single module will not affect the other modules.
  • Since the modules are separate, you can increase the scalability of the module which is needed more at the appropriate time as compared to increasing the scalability of the whole application.
  • The deployment becomes much faster as the codebases are small.
  • Microservice provides the flexibility to work on a new technology stack on an individual part of code and because of loose coupling rolling back changes becomes easy.
Immense knowledge working with DevOps -

Java developers require DevOps skills for Continuous Integration and Continuous Deployment (CI/CD). Freelance Java Developers must know –

  • Programming best practices
  • Building scripts and guidelines
  • Creating an infrastructure environment.

The main DevOps tools which a freelance Java developer must know are –

  • Continuous Development – Git, SVN, Jira, Mercurial, CVS.
  • Continuous Integration – Bamboo, Jenkins, Hudson
  • Continuous Delivery – Tomcat, Nexus, Archiva.
  • Continuous Deployment – Docker, Chef, Puppet.
  • Continuous Monitoring – ELK Stack, Nagios, Splunk.
  • Continuous Testing – Katalon Studio, Selenium, Appium, Eggplant, Watir, Tosca.
Experienced in working with Version Control System (VCS)

Developers must have a very good knowledge of version control systems, like Git, SVN, TFS, and Mercurial. Mostly, developers use Git for their work. It is the version control system that helps the team in collaborating and organizing your code, maintain the frequent changes that occur in the code. Git helps in reviewing the old codes and compares them with the newly updated code, pulling the code from their repository, and managing the commit history.

Along with this, the developer must know how to use add, push, pull, and commit commands, branching, and merging as it allows developers to work independently on the code.

Knowldege of Spring Boot
A Java developer must know about Spring Boot, an open-source microservice framework. Spring Boot helps developers to create web applications without the need for any external server, reduces development time, and increases the efficiency of an application. It embeds a web server like Tomcat or Jetty in its application. Spring MVC defines each dependency separately and groups them into a single unit. Also, it simplifies the integration with other Java frameworks like – Hibernate ORM / JPA, Struts/JSF, etc.   Spring Boot provides CLI tools for creating and executing web applications. Spring Boot provides support for the following – 
  • Project Support
  • Starter Project Wizard
  • Command Line Interface (CLI)
  • Hibernate ORM / Java Persistent APIs (JPA)
  • Spring Initializr
  • Annotations
  • Java Database Connectivity (JDBC)
  • Starters
  • Actuator
  • Transaction Management.
 
Knowledge of MVC Architecture
MVC stands for Model-View-Controller architecture. MVC design pattern separates the application logic from the view logic (user interface) while developing software. It consists of three layers mainly – 
  • Model – Model represents the business layer of an application.
  • View – View is the User Interface of an application.
  • Controller – Controller manages the application flow.

In the context of Java programming, 
  • The Model consists of Java classes, 
  • The View is responsible for displaying data,
  • The Controller provides the retrieved data to the View and the View is rendered and sent back to the browser to display the data to the client. 
Experience with web markup and UI, UX Concepts

The developer must have a firm understanding of element positioning, displaying the elements, and making components interactive, semantic markup, and other related UX Concepts so they can design the product with the best quality. The developer must be experienced in developing visual effects in presentational markup. For, example – How the heading appears, making text larger and putting weight to it, and giving which color to it, and which markup can include captions, bind columns, and row headings to table cells. 

Strong grasping on JVM internals
While hiring a Java developer, make sure the developers know the following JVM internals – 
  • JVM Options
  • JIT
  • Garbage Collection
  • Race Conditions
  • Concurrency Handling
  • CPU and RAM Connection
  • Collector
  • Performance Bottlenecks
  • Execution Model
 

Pay only after one week trial period

Connect with the top 1% freelance Java developers of the world at the lowest prices

Java is a robust programming language because of its flexibility to work on both client-side and server-side. Large number of remote java developers are competing to get hired. Ultragenius filters out the most skilled freelance Java developers to connect you only with the top 1% among 20K+ remote Java developers.

Top Interview Questions to ask while hiring a freelance Angular.js developer

Constructor Overloading in Java is the concept of having different definitions of a constructor based on different parameters, so that each constructor can perform a different task from another. Consider an example,

public class Bank{ 
public Bank(){

System.out.println(“This is a default constructor”);
}


public Bank (String name){

System.out.println(“Bank name is  :” + name);




public static void main(String[] args){ 

Bank bank = new Bank (); 
Bank bank2 = new Bank(“Bank of India”);

}

}

Output - 

This is a default constructor

Bank name is Bank of India


this() is used to call the current class constructor in Java. 


public class Bank{ 

public Bank(){

this(“hello”);

System.out.println(“This is a default constructor”);

}


public Bank (String name){

System.out.println(“Bank name is  :” + name);



public static void main(String[] args){ 

Bank bank = new Bank (); 

Bank bank2 = new Bank(“Bank of India”);

}

}


Output - 
Bank name is Bank of India
This is a default constructor

  • When a variable is final, its value cannot be changed, but when a variable is static only one copy of that variable is shared among all the objects of the class.
  • A final method cannot be overridden by its child class whereas a static method can be invoked without creating the object of the class containing that method, it may/may not get overridden by its child class. For example, main method in Java  is static because it has to be loaded before the  instantiation of a class takes place.
  • To restrict the inheritance of a class, final keyword is used with the class so its child class cannot extend it whereas a class can be declared static only when it is a nested class in Java, the advantage is that objects of a static class can be created without any need of creating the instance of its outer class.

For example, 

class Demo{ 

class A{} 

static class B{} 

public static void main(String[] args){ 

A a = new A(); /* it will show compile time error, you need an instance of Demo to instantiate A;*

B b = new B(); /*it will compile successfully, no instance of Demo needs to be created to instantiate B.*/


  }

}

Constructor call is always the first statement. Either you can use this() inside the constructor or super(), this() is used to invoke the current class constructor of a class, while super() is used to invoke the parent class / superclass constructor of that class.

 

The main method in Java is - public static void main(String[] args) Every word in main method conveys a meaning to the JVM - 
    • public - The keyword public indicates that main method is accessible globally as it is the entry point of the program execution so JVM can invoke it from outside the class.
    • static - The main method has to be invoked even before instantiating that class, so it is declared as static.
      • void - In C++, the return type of main method is declared as int, which indicates the exit code status of a program which is the process of Operating System, return 0 means program executed successfully and non-zero exit code means there is an error in the program. These programs are the sub-process of the main process which after receiving their exit code cleans up the sub-process from the process table and frees the memory allocated to that process, that is why it is compulsory to pass exit code for the C++ programs. But in Java, the program runs as the main thread and there is no direct allocation of resources to a Java program. That is why main method in Java does not return anything.
     
      • main - main is the starting point the JVM looks for when executing a Java program.
     
    • String[] args - It is an array of java.lang.String class. String[] args can also be written as String...args or String args[], which accepts command line arguments.
JVM stands for Java Virtual Machine. It is a run-time environment that takes Java bytecode as input and converts it into assembly or machine code line-by-line. The memory areas allocated by JVM are - 
  • Class (Method) Area

  • Heap

  • Stack

  • Program Counter Register

  • Native Method Stack
  • Class (Method) Area - This memory stores data at the class level like method data, runtime constant pool, and program code of methods.
  • Heap - Heap is used for dynamic memory allocation.
  • Stack - In JVM, the Stack is used to store frames. Every time a method is invoked, a new frame is created and destroyed when the invocation completion.
  • Program Counter Register - A JVM thread that performs a specific task of a method has a program counter associated with it. 
Native Method Stacks - Native method stacks are also called as C Stacks. This memory can be fixed or dynamic and is allocated for each program thread when the thread is created.

this keyword in Java is used in - 

  • Referring to class variable when both, class variable and local variable have same name.
  • Invoking the current class constructor.
  • Passing it as an argument in method call.
  • Passing it as an argument in the constructor call.
  • Returning the current class object from the method.

Aggregation represents one-to-many relationship and is unidirectional in nature. Aggregation defines has-a relationship. Both the objects in aggregation can exist independently which means ending one object doesn’t affect another entity.  For example, Bank has-a Customer, if Bank gets destroyed Customer will still remain. Aggregation is a weak association. Code resusability is best achieved by Aggregration. 

Composition defines a part-of relationship, i.e., child cannot exist independent of the parent. For example, engine is a part-of the car. If the car gets destroyed, then engine also gets destroyed. Composition is a strong association. Multiple Inheritance which cannot be achieved by Inheritance, can be achieved by Composition. 

  • Java Server Pages (JSP) use Java inside HTML provides ease to the developer to write, debug, and edit the code whereas Servlets use HTML in Java which makes the code complicated. 
  • Servlets use println statements for printing an HTML doucment whereas JSP does not.
  • View logic and Business logic is separated in JSP which is not possible in Servlet.

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Frequently Asked Questions

Ultragenius is one of the leading platforms for hiring remote talent and connecting freelance and part-time developers with Silicon Valley businesses. We focus on finding the best talents who will perform extremely well and will be easily integrated into your teams. We filter out only the top 1% most skilled freelance developers among the 20K+ developers who have applied on our platform. Candidates have to prove their self-reported experience by giving Ultragenius’ s skill tests.

Ultragenius first tests the developer’s skill set by conducting a two and half hour hiring test. Our hiring test judges a candidate on all aspects like aptitude, case study analysis, verbal and reasoning, coding questions based on data structures and algorithms, software engineering, system design, and more. Then, there is another round for the candidates who are selected from this round called “Higher-level Assessment Skill Test”, which is a video round that deeply analyzes freelance developers’ major skills and asks questions about the projects they have worked upon.

Fill up the form which is on every hiring freelancers’ page and we will inform you once we select the top 1% freelance Java developers matching your job requirements.  After analyzing the candidates based on their resumes and two assessment tests, we provide you the feedback quickly. And if the freelancers selected by our team are fit for your job role, then we also provide the onboarding.

Ultragenius offers you only the most skilled freelance developers who are top 1% among the 20K+ freelance developers who have applied on our platform. After a rigorous selection and testing process, we sort out only the top candidates for you. You can check out Ultragenius’ s selection process for hiring freelance Java developers on http://www.ultragenius.club/hire-java-freelancer

 

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