Java Q and A for Interview Success | iCert Global

Are you getting ready for a Java job interview and want to know the most common questions? You're in the right place! This blog will show you important Java questions that can help you do great in your interview. We’ll talk about topics like Java basics, Java OOPs, Java coding, Java Spring, and more. These questions and a Java certification can help you get the job you really want. Sign up for a Java course and earn your certification today!

Q1. What is Java?
Java is a computer language that uses classes and objects to build programs. It doesn’t need a lot of extra tools to run. Java is made so that you can write the code once and use it on many different computers. This means the same Java code can run on any computer that supports Java, without changing it.

Q2. What are the main features of Java?
Java is easy to learn and use. To understand Java, you need to know the basics of how objects and classes work.
Java is built to be safe, so it helps stop viruses and protects the system.
OOP means Object-Oriented Programming, which is a way of thinking where everything in Java is treated like an object..

Q3. How is Java different from C++?
Java and C++ are both used to write computer programs, but they have some important differences.

• Works on different computers: Java can run on any computer that has something called a Java Virtual Machine (JVM), so it's called platform-independent. C++ can only run on the type of computer it was made for, so it's platform-dependent.
• Memory use: Java handles memory by itself, so the programmer doesn't need to worry about it. In C++, the programmer has to manage memory by hand, which can be tricky and may cause problems if done wrong.
• Safety: Java is safer than C++. Java has built-in features that protect it from harmful code. For example, it doesn't let programs directly touch the computer’s operating system, which helps stop hackers.
• Speed: C++ is usually faster than Java because Java uses a virtual machine, which can slow it down a little. But Java is better for writing programs that can work on many types of computers and are more secure.
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Q5. What is public static void main(String[] args) in Java?
This is the line that starts every Java program. It tells the computer where to begin running the code. The word main is the name of the method, and it’s the first thing the computer looks for when starting a Java program. It always looks like this:
public static void main(String[] args)

Here’s what each word means:

• public: This means anyone can use this method. It’s open for all classes to access.
• static: This means the method belongs to the class, not an object. So, you can run it without making an object first.
• void: This means the method doesn’t return any value. It just runs and ends.
• main: This is the name of the method. The computer looks for this to start your program.
• String[] args: These are the inputs you can give your program when it starts. Most programs don’t need them, but they are there if needed.

 Q6. What is a ClassLoader in Java?
A ClassLoader is part of Java that loads code (called class files) so the program can run.
There are three main types:

1. Bootstrap ClassLoader – Loads the basic Java tools.
2. Extension ClassLoader – Loads special tools for extra features.
3. System/Application ClassLoader – Loads the code you write in your program.

Q7. Why is Java called platform independent?
Java is platform independent because the code is turned into something called bytecode. This bytecode can run on any computer that has the Java Virtual Machine (JVM), no matter what operating system it uses—like Windows, Mac, or Linux.

Q8. Why isn’t Java 100% Object-Oriented?
Java is not fully object-oriented because it uses some basic types, like int, char, float, and boolean, which are not objects. These are called primitive data types and are used to make programs faster and simpler.

Q9. What are Wrapper Classes in Java?
Wrapper classes turn these basic types (like int or char) into objects. Every simple type has a matching wrapper class. For example, int becomes Integer, and char becomes Character. These classes “wrap” the value into an object so you can use it like other Java objects.

Q10. What are Constructors in Java?
A constructor is a special block of code used to create an object in Java. It has the same name as the class and doesn’t return any value. When you make a new object, the constructor runs automatically to set it up.

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Conclusion:
Java is a powerful and widely used programming language that’s easy to learn and works on many devices. Understanding basic concepts like main(), ClassLoaders, constructors, and wrapper classes can help you do well in interviews and build strong programs. To boost your skills and get certified, check out the Java course from iCert Global and start your learning journey today!

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