Best Java Interview Questions and Answers for 2023 (Latest)

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Earlier, we discussed part 1 of Java Interview Questions and Answers. Today, we will a set of Java Interview Questions and answers for beginners and professionals. Here, we are providing Interview Questions for Java which will help you to crack your Java Interview. These tricky Java interview questions and answers are designed by Java professionals.

So, let’s start Java Interview Questions and Answers for 2023.

Frequently Asked Java Interview Questions and Answers

Below, we are discussing top Java Interview Questions and Answers:

Q.1 Can a class be defined within an interface?

Yes, it’s attainable.

Q.2 Can an interface be defined within a class?

Yes, it’s attainable.

Q.3 What’s A Marker Interface?

A Marker Interface is an interface which does not have any declaration within however still enforces a mechanism.

Q.4 What restrictions are placed on the location of a package statement inside a source code file?

The restriction that is placed is that the package statement must appear as the first line in a source code file (excluding blank lines and comments).

Q.5 If I only change the return type, will the method become overloaded?

No, it does not. There should be a change in method arguments for a method to be overloaded.

Q.6 Why will Java Not Support Operator Overloading?

To keep up code simplicity, Java does not support operator overloading as operator overloading makes the code terribly difficult to read and maintain.

Q.7 What’s Externalizable?

The Externalizable interface in Java is used to alter how an object is serialised and deserialized. The writeExternal() function specifies how the object’s state should be written to a stream, and the readExternal() method specifies how the object’s state should be rebuilt from a stream. Classes that implement the Externalizable interface must override both of these methods.

Developers have complete control over the serialisation format using Externalizable, in contrast to Java’s built-in serialisation mechanism (Serializable interface), which limits their ability to create more effective and specialised serialisation logic. However, compared to Serializable, it also requires more work to implement since the developer must manage every part of the object’s state during serialisation and deserialization.

Q.8 What modifiers are allowed for methods in an interface?

Interfaces allow only two methods that are, public and abstract.

Q.9 What’s a local, member and a class variable?

Variables declared inside a method are “local” variables. Variables declared inside the class i.e. not inside any methods are “member” variables (global variables). A variable declared inside the class i.e. not inside any methods and are defined as “static” are class variables.

Q.10 What’s an abstract method?

The “abstract” keyword in the method declaration designates a method that has been declared in Java but does not have a method body. By supplying the method’s signature (name, return type, and parameters) but not the actual implementation details, it acts as a template for subclasses to follow. The “abstract” keyword must be used to define the class itself as abstract before any abstract methods may be declared within it.

All abstract methods must have concrete implementations in subclasses that extend the abstract class, or else they must be explicitly stated as abstract. In order to achieve abstraction in object-oriented programming and provide a common interface for related classes, abstract methods defer the implementation details to the subclasses.

Latest Java Interview Questions and Answers

Here, we collect the latest or advanced java interview questions and answers.

Q.11 What value does read() return when it has reached the end of a file?

The read() method returns -1 when it’s reached the end of a file.

Q.12 Will a byte object be cast to a double value?

No, an object cannot cast a double value.

Q.13 Difference between a static and a non-static inner class?

A non-static inner category could have object instances that are related to instances of the category’s outer class. A static inner category doesn’t have any object instances.

Q.14 What is an object’s lock and which objects have locks?

An object’s lock is a mechanism that is used by multiple threads to get synchronized access to the object. A thread may execute a synchronized method of an object only after it’s acquired the object’s lock. All objects and classes have locks. A class’s lock is acquired on the class’s class object.

Q.15 What’s the youngster’s Operator?

It is referred to as the modulo or remainder operator. It returns the rest of dividing the first operand by the second operand.

Q.16 Will an object reference be cast to an interface reference?

Yes, it can be but only when an object reference is cast to an interface reference when the object implements the referenced interface.

Q.17 Which non-Unicode letter characters is also used as the 1st character of an identifier?

The non-Unicode letter characters $ and I may appear as the 1st character of an identifier.

Q.18 What restrictions are placed on method Overloading?

Two methods may not have the same name and argument list however different return types.

Q.19 What is Transient variable?

A transient variable in Java is one that has the term “transient” in its declaration. Transient variables are not included in the serialisation process when an object is serialised (converted to a byte stream) using the Serializable interface. This indicates that when the object is serialised or deserialized, their values are not preserved or restored. Transient variables are frequently used for information that shouldn’t be preserved during object serialisation, such as momentary or sensitive data that may be reinitialized after deserialization.

Q.20 What’s collection API?

The Collection API is a set of interfaces and many classes that support operation on collections of objects. These classes and interfaces happen to be much more flexible, more powerful, and more regular than the vectors, arrays, and hash tables if effectively replaces.

Tricky Java Interview Questions and Answer

These are the trickiest Java interview questions and answers:

Q.21 What’s Casting?

There are 2 forms of casting, casting between primitive numeric types and casting between object references. It can be done between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.

Q.22 If a variable is declared as private, where may the variable be accessed?

A private variable may only be accessed within the class in which it is declared.

Q.23 What do you understand by private, protected and public?

These are accessibility modifiers. Private is that the most restrictive, while public is that the least restrictive. There is no real distinction between protected and therefore the default type (also referred to as package protected) within the context of the same package, but the protected keyword allows visibility to a derived class during a different package.

Q.24 What modifiers may be used with an inner class that’s a member of an outer class?

The mpdifiers that can be used are such as the (non-local) inner class is also declared as public, protected, private, static, final, or abstract.

Q.25 What number Bits are used to Represent Unicode, ASCII, Utf-16, and Utf-8 Characters?

Unicode needs sixteen bits and ASCII need seven bits. Though the ASCII character set uses solely seven bits, it’s typically represented as eight bits. UTF-8 represents characters using 8, 16, and 18-bit patterns. UTF-16 uses 16-bit and bigger bit patterns.

So, this was all in best Java Interview Questions and answers.

Conclusion

Hence, at the end of these Java interview questions and answers, you were ready to give an interview for a fresher level. Refer our next part to enhance your knowledge. We hope these Java Interview Questions and Answers helped you. Still, if any doubt, ask in the comment tab.

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1 Response

  1. vennela Vpf says:

    I improved my skills through the course

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