Top 5 Java interview questions with answers

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Top 5 Java interview questions with answers

What is the difference between JDK, JRE, and JVM?
JDK stands for Java Development Kit, which includes the JRE (Java Runtime Environment), compiler, and other development tools. JRE is the runtime environment for Java applications and consists of the JVM (Java Virtual Machine) and other necessary libraries. JVM is responsible for running Java bytecode on different platforms.

What is the difference between an abstract class and an interface?
An abstract class can have both concrete and abstract methods, while an interface can only have abstract methods. An abstract class can also have instance variables, whereas an interface cannot. A class can extend only one abstract class but can implement multiple interfaces.

What are the access modifiers in Java?
Java has four access modifiers: public, private, protected, and default. Public allows access from anywhere, private allows access only within the class, protected allows access within the same package and subclasses, and default allows access within the same package.

What is a static method and a static variable?
A static method belongs to the class and not the object of the class. It can be called without creating an object of the class. A static variable is a class variable that belongs to the class and not to the object of the class. It is shared among all instances of the class.

What is the difference between a stack and a queue?
A stack is a data structure that follows the LIFO (Last In First Out) principle, where the last element added is the first one to be removed. A queue is a data structure that follows the FIFO (First In First Out) principle, where the first element added is the first one to be removed.