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Best Interview Questions to Ask an Entry Level Java Developer

programming in a laptop with a note pad with a pen

Are you looking to hire a Java developer? Do you have interviews coming on the way? The best way to identify a talented developer is to understand what their role and main functions will be. This means you need to talk the same language as them (not literally) but do understand what you are asking. Otherwise, they could start talking technical concepts while you are in lalaland trying to figure out what they mean. As remote tech recruiters, we have interviewed Java developers for more than a decade.  In this article, you’ll learn the best interview questions to ask an entry-level Java developer. 

Java Overview

Java is one of the most popular programming languages worldwide. Over 9 million developers use it daily. These are some interesting facts of this programming language: 

  • Java’s initial name was ‘’Oak’’.
  • It was developed in 1995 by Microsystems (Now it belongs to Oracle).
  • Most developers who use Java build software, computer games, and mobile apps.
  • It’s the second most popular language.
  • Java is the programming language of Android.
  • It’s used by 95% of the enterprises as their primary language.

Why Hire a Java Developer? 

For many, 2020 is known as the ‘quarantine year.’ Most companies who had to lock their doors started strengthening their online presence.  Some of them use LinkedIn strategies or any type of social media to connect with their customers. Others opt for a more significant digital presence by building business applications and websites. The results? More loyal customers and engaged users that turn into potential customers. 

If you hire a Java developer, you’ll have someone on your team capable of designing, developing, and managing Java-based applications. Different applications such as: 

  1. Mobile applications
  2. Desktop GUI applications
  3. Web-based applications
  4. Enterprise applications
  5. Scientific applications
  6. Gaming applications
  7. Big Data technologies
  8. Business applications
  9. Distributed applications
  10. Cloud-based applications

Best Java Interview Questions for Entry Level Java Junior Developers 

Junior Java developers are a great way to strengthen your IT team. Although they are still not experts on the field, they have valuable and fresh knowledge. Talented junior developers are aware of all the new things happening in the programming world, and they bring a great set of skills your team needs. But how to identify a junior developer who won’t mess anything up?

Many managers (not only in the IT industry) avoid junior employees because they think they don’t have time to teach them things. Or they are scared that juniors will screw things.  Yet, junior employees have all the new ideas, and information seniors sometimes are lacking. If you have an upcoming technical interview with an entry-level Java developer, you should know that identifying talented ones is not easy. That’s why we made a list with the 8 best junior Java developer interview questions:

1. How does Java achieve platform independence?

Java platform independency means that the Java program can run on any platform or operating system without suffering any changes. This is possible because of the bytecode. 

When the Java program runs in a particular machine it is sent to the Java compiler. The result of this is the conversion of the original code into an intermediate code called bytecode. This bytecode is sent to Java Virtual Machine (JVM) which resides in the RAM of any operating system. JVM recognizes the platform and converts the bytecodes into native machine code.

2. What are the various access specifiers for Java classes?

Access specifiers are the keywords used before a class name that defines the access scope. 

There are four types of access specifiers:

1.  Private: When a variable is declared as private, it can be accessed only from the same class to which they belong.
2.  Public: Methods and variables that have public access can be accessed by all the other classes in the project.
3.  Protected: When a variable is declared as protected it means that it can be accessed within the same package classes and subclasses of any other packages.
4.  Default: Methods and variables can be accessed only from the same package and not from outside of its native package.

3. What is the Difference Between ArrayList and HashSet in Java?

The following ones are the main differences between ArrayList and HashSet: 

Implementation

ArrayList: Implements List interface.

HashSet: Implements Set interface.

Duplicates

ArrayList: Allows duplicates values.

HashSet: Doesn’t allow duplicates values.

Constructor

ArrayList: Have three constructor which are ArrayList (), ArrayList (int capacity), ArrayList (int Collection c).

HashSet: Have four constructor which are HashSet (), HashSet (int capacity), HashSet (Collection c), and HashSet (int capacity, float loadFactor).

Order

ArrayList: Maintains the order of the object in which they are inserted.

HashSet: Doesn’t maintain any order.

Null Object

ArrayList: It’s possible to add any number of null value.

HashSet: Allow one null value.

Syntax

ArrayList:

ArrayList list=new ArrayList ();

HashSet:

HashSet set=new HashSet ();

4. What is a Java ClassLoader?

The Java Classloader belongs to the Java runtime environment that loads classes on demand into the Java Virtual Machine (JVM). Classes are loaded from the local file system, a remote file system, or even from the web.

When the JVM is started, three class loaders are used:

1.   Bootstrap Classloader: Loads core Java API file rt.jar from folder.

2.   Extension Classloader: Loads jar files from folder.

3.   System Classloader: Loads jar files from path specified in the CLASSPATH environment variable.

5. Explain the main difference between fail-fast and fail-safe iterators

The main difference between fail-fast and fail-safe iterators is whether or not the collection can be modified while it is being iterated.

Fail-fast iterators operate directly on the collection itself. This means that during iteration, fail-fast iterators fail as soon as they realize that the collection has been modified.

Fail-safe iterators operate on a cloned copy of the collection and therefore do not throw any exception if the collection is modified during iteration.

6. What are loops in Java? – Explain the three types of loops 

Loops are used in Java to execute a statement or a block of statement repeatedly. There are three types of loops in Java:

1. For Loops

For Loops are used in Java to execute statements repeatedly for a given number of times.

2. While Loops

While Loops are used when determined statements need to be executed repeatedly until a condition is fulfilled.  In While Loops, condition is checked before the execution of block statements.

3. Do While Loops

Do While Loop is the same as While loop with the only difference that condition is checked after the execution of block statements. 

7. What is the Final Keyword in Java? – Provide an example

In Java, the final keyword is used in several contexts to define an entity that can only be assigned once. This means that when using the final keyword, the value can’t be modified in the future. Once a final variable has been assigned, it ALWAYS contains the same value.

For example, if you ever see the final keyword with a parameter variable, it means that the value of this variable cannot be changed anywhere in the function. For example: 

class finalParameter {
	public static void example( final int parameter ) {
      parameter = 4; //attempting to reassign a value to a parameter throws an error
	}
}

8. What is default switch case/ – Provide an example

In a switch statement, default case is executed when no other switch condition matches. It can be declared only once all other switch cases have been coded.

For example:

public class switchExample {
	int score = 4;
	public static void main(String args[]) {
        switch (score) {
            case 1:
                system.out.println("Score is 1");
                break;
            case 2:
                system.out.println("Score is 2");
                break;
            default:
                system.out.println("Default Case");
    	}
	}
}

Need Help Hiring an Entry Level Java Developer?

Suppose you are still wondering what are the basic questions asked in Java interviews, or how to conduct a more technical interview, including specific coding questions. In that case, your best option is to get help from experts.  Having technical background during interviews is necessary, but also interviewers need specific skills to know when a candidate will fit into a company’s culture and when they are not. Plenty of candidates have a solid skillset but hate code reviews or can’t stand working on teams.  But don’t worry! At DistantJob, all of our headhunters are skilled enough to identify the most talented junior Java remote developers that will fit your company perfectly. All you need to do is:

1.   Contact us.

2.   Tell us the skills you are looking for in candidates.

In less than two weeks, you’ll be onboarding your new entry-level Java developer.

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