Sometimes nervousness might take the lead and you might find yourself in a difficult situation, not knowing what to say or how to respond. To avoid this, however, and to ace the interview, you should come prepared. This tutorial about Java interview questions will help you do exactly that.
I’ve segmented them into a few groups to make it easier to learn and remember. These questions (or, rather, their answers) will help you ace that interview and land the job as a Java developer in no time!
Experienced Questions of Java
Question 1: What’s the difference between ‘method overloading’ and ‘method overriding’?
One of the first possible basic Java interview questions could be this one. In a “method overloading” case, methods that are in the same class share the same name, yet their parameters differ. This is concerned with extensions of the method’s behavior more than anything else. Reversely, “method overriding” sub-classes have methods of the same name and parameters. The aim here is to alter the already-existing method’s behavior.
Just to give you an example, here’s method overloading:
And this is method overriding:
Question 2: What’s the output of this Java program?
The correct answer is this:
a = 30 b = 65
Question 3: Is it possible to execute a program without the ‘main() method’?
Pretty standard among Java interview questions and yes, it is possible to do that. One of the most common ways to execute a program like that is by using a static block.
Question 4: What is ‘runtime polymorphism’?
A “runtime polymorphism” is a process in which a specific call that is issued to an overridden method will be resolved in runtime instead of compile time. Here’s an example:
Question 5: What is ‘Inheritance’?
The term is honestly almost self-explanatory – inheritance is when one object acquires the properties and parameters of another one (of a different class). The above-discussed method overriding uses this – the main idea of inheritance is that you can build new classes on already-existing ones. There are five different types of inheritance, but Java only supports four (Multiple inheritances aren’t supported). Why aren’t Multiple inheritances supported? There’s only one specific reason – to simplify the program. This should be an important note to remember for your Java interview questions.
Question 6: Name the superclass for all other classes in Java.
This is one of the easier ones – however, I should also add that it’s one of the core questions. The superclass in Java is the object class.
Question 7: What does ‘super’ in Java mean?
“Super” in Java is used as a reference to point to an immediate parent class object. The command can also be used to invoke immediate parent class methods and constructors.
Question 8: What is the output of this Java program?
Animal class constructor called
Zebra class constructor called
These are very common Java interview questions. Always pay attention to the variables – they define the final answer.
Question 9: What is ‘association’ in Java?
One of the more asked Java coding interview questions, this might not seem like an “advanced” one at first. However, things like aggregation and composition stem from the association, so it is important to understand the term.
Association is when all objects have their lifecycles and no specific owner exists. It can vary between “one” and “many”.
Question 10: What’s ‘object cloning’?
The “object cloning” command is used to create an identical copy of the object. This is done by using the clone() method from the Object class.
Tips for the Interview
I probably don’t need to mention the whole good night’s sleep and healthy breakfast scenarios – you’ve probably heard it all at least a thousand times already. What I can say is that you most definitely shouldn’t be up at 3 AM revising your basic Java interview questions when you’ve got the interview at 8 AM the next day. There’s no need to stress – try not to think about the interview at least 24 hours up to it – revise your notes only on your way to the interview.
Also, act relaxed when you’re there. If the employer sees that your nervous, he might think that you’re worrying because you’ve got something to hide – perhaps a lack of skill? Though – find the perfect balance between being confident and leaving room for improvisation.
With a need for programmers on the rise, multiple companies and individual employers are looking for experienced professionals in the field of computer coding. Because Java is one of the most popular programming languages in the world (thanks to its flexibility, security, and simplicity), many potential programmers choose it as their primary language to learn. In this tutorial, I’ve shown you some core Java interview questions and answers. There are many more Java coding interview questions that you might get asked during your job interview, but if you know these, you’re already set on a good path.