Hire The Top 1% Freelance Java Spring Developers

The Spring Framework is an open-source application framework for developing Java applications. Java Enterprise Edition (Java EE) is one of the most popular frameworks, Spring helps developers create high performing applications using reusable and efficient code.

If you’re looking for a freelance Java Spring developer, this guide will come handy. We’ve included everything you need to know about the hiring process.

But before we get into the fundamentals of hiring a freelance Java Spring developer, let’s delve into some interesting facts about Java.

We have broken the sections into the following parts:
1. Let's introduce Spring Framework to you.
2. Why is Spring Framework widespread?
3. What are the tools used by Spring developers?
4. Writing the Job Description to hire a Java Spring developer
5. Interview Questions for hiring a Java Spring developer
- Basic Questions
- Advanced Questions
- Data Structures/Algo Questions

1. Let's introduce Spring Framework to you

• Spring framework was first written by Rod Johnson in 2002. The framework was first released in June 2003 under the Apache license version 2.0.


• Spring Framework is a Java platform that provides comprehensive infrastructure support for developing Java applications.


• Spring handles the infrastructure so developers can work on creating applications.


• Spring framework is very developer friendly. It’s easily testable and lightweight, modular and configurable.


• Spring simplifies the complex enterprise Java application development process by offering a framework that includes technologies like Aspect-oriented programming (AOP), Dependency injection (DI) and Plain Old Java Object (POJO).



2. Why is Spring Framework widespread?

• Spring’s libraries are trusted by developers globally. Spring caters to millions of users in the form of various services like streaming TV and online shopping. Spring is also used in giant tech firms like Amazon, Google, Microsoft, and more.
• Spring Framework provides a wide range of features and functionality. Spring has the tools to help if you’re building secure cloud-based products and data streaming flows for any enterprise.



3. What are the tools used by Spring developers?

The following are some of the tools used by Spring developers at various stages of development:

1. IDE
An integrated development environment (IDE) is a software application that builds applications and combines common developer tools into a single GUI.

• Spring Tool Suite - is an open-source Java IDE made for developing Spring-based enterprise applications. It is easier and faster, based on Eclipse IDE.
• IntelliJ IDEA - provides built-in developer tools for the Spring Framework with extensive coding assistance including a dedicated project wizard and code highlighting.
• MyEclipse Spring IDE - the Spring version of MyEclipse is specifically designed for developers using Spring Framework. It allows developers scaffolding and project bootstrapping for advanced projects.

2. Plugins
Plugins are computer software that adds new functions to a host program without altering the host program itself.

• Spring Maven - is a plugin that allows developers to package executable jar or war archives and run Spring applications prior to running integration tests.



4. Writing the Job Description to hire a Java Spring developer

Below are some key points that we at Flexiple have learned through trial and error - a process of filtering through over 15,000 developers.

• Years of software development experience: Be specific about the technology you’re looking for and the number of years of experience needed. A proxy to years of experience can be the number of production-level apps worked on.


• Expertise in a specific framework: All frameworks have their peculiarities and nuances. While good Java developers can pick up other frameworks, it’s a plus point to hire a developer who already has expertise in it.


• Type of products built in the past: Based on the type of product you are trying to build - social network, SAAS product, etc. - you can prioritize certain developers over others.


• Exposure to specific industries: Developers who have built products in certain industries will already know key aspects of laying the foundation for a great product and will be able to predict possible problems.


• Experience working remotely: Hiring someone who has worked remotely in the past is an added advantage as they would have first-hand experience of everything right from how contracts work to communication and from timelines to deliverables.


• Strong communication: An essential thing to look at when hiring a freelancer is excellent communication skills. Since all the interaction happens online, freelancer should be able to effectively communicate to ensure a streamlined execution of all work.



5. Interview Questions for hiring a Java Spring developer

Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants. To help you with that, we have created a pool of questions that a good Java Spring developer should be comfortable with. You can check out some related interview questions on this page.

It is important to note that the ability to answer these questions doesn't imply that you have a top quality candidate. But it definitely is a big step in that direction.

To help you navigate through these questions, we’ve categorized the interview questions in 3 parts:


A. Basic concepts: Includes all basic concepts used across languages but we've focused on its significance in Java Spring Development. This section will give you an understanding of how strong their programming foundation is.

B. Advanced concepts: Includes all concepts that someone with higher expertise should know.

C. DS/Algorithm questions: To test the logical capability of the candidate.




A. Basic concepts

An interface that contains only one abstract method is called a functional interface. Subsequently, functional interfaces can have only one functionality, however, they could contain multiple default methods.

With Java 8, lambda expressions can be used to instantiate functional interfaces making it much easier.

Examples of functional interfaces include - ActionListener, Comparable

Here is the code used to define a functional interface.

@FunctionalInterface
interface Foo {
    void test();
}

• Nesting Locks: A major cause of deadlocks is when locks are given to multiple threads. Avoiding giving locks to multiple threads in case a thread with a lock already exists can help prevent deadlocks.
• Using the Thread.join(): Deadlocks can also appear when a thread waits for a resource from another thread. However, in such cases the Thread.join() can be used with the maximum execution time.
• Using Lock only when necessary: Practice using locks only on members when it is required. Having unnecessary locks is a major cause of deadlocks.

B. Advanced concepts

Memoization is an approach that helps solve problems caused by dynamic programming. This process ensures that a given method does not execute more than once for the same inputs.

The return values are stored in Hashtables or Hashmaps and reused whenever required.

The code below is an example of memoization in a Fibonacci series.

 import java.io.*;

class GFG
{
    
// Fibonacci Series
// using Recursion
static int fib(int n)
{

    // Base case
    if (n <= 1)
        return n;

    // recursive calls
    return fib(n - 1) +
        fib(n - 2);
}

// Driver Code
public static void main (String[] args)
{
    int n = 6;
    System.out.println(fib(n));
}
}

C. Data Structure/ Algorithm

class Test {
public static void main(String args[])
    {
        String str1 = new String("Hello World");
        String str2 = new String("Hello World");

        String str3 = "Hello World";
        String str4 = "Hello World";

        int a = 0, b = 0, c = 0;

        if (str3 == str4)
            a = 1;
        else
            a = 2;

        if (str1.equals(str3))
            b = 1;
        else
            b = 2;

        if (str1 == str4)
            c = 1;
        else
            c = 2;
        System.out.println("a= " + a + " b= " + b + " c= " + c);
    }
}

D. a=1 b=1 c=2 because a new memory is created when we make an object with the help of the ‘new’ keyword, 
and the reference variable contains the memory location. 
Here the memory is created with the same string twice, but since we are comparing objects and not strings, 
the object will point to a different memory location and so they are not equal. 

Parting thoughts on hiring Java Spring developers