Mastering Java Concepts

What is the main feature of Java's platform independence?

• Java bytecode can run on any platform with a compatible JVM.

• Java applications can only run on Windows operating systems.

• Java bytecode is specific to the hardware architecture.

• Java code must be compiled for each platform separately.

Explain the concept of Object-Oriented Programming in Java.

• Object-Oriented Programming in Java is only about data structures.

• Java does not support Object-Oriented Programming principles.

• Object-Oriented Programming in Java is a paradigm that uses objects and is based on principles like encapsulation, inheritance, polymorphism, and abstraction.

• Object-Oriented Programming in Java is solely about using functions.

What is the difference between JDK, JRE, and JVM?

• JDK is for running applications, JRE is for execution, and JVM is the development kit.

• JDK is for development, JRE is for running applications, and JVM is the execution engine.

• JDK is the execution engine, JRE is for development, and JVM is for running applications.

• JDK is a runtime environment, JRE is for compiling code, and JVM is a programming language.

How does Java achieve memory management?

• Java uses a stack-based memory management system.

• Java does not manage memory automatically and relies on the programmer.

• Java requires manual memory allocation and deallocation.

• Java uses automatic garbage collection for memory management.

What are the access modifiers in Java?

• static, final, synchronized, volatile

• abstract, native, strictfp, transient

• interface, enum, class, package

• The access modifiers in Java are public, private, protected, and default.

What is the purpose of the 'static' keyword in Java?

• The 'static' keyword allows class-level access to variables and methods without needing an instance.

• The 'static' keyword is used to define abstract classes in Java.

• The 'static' keyword is used to create private variables only.

• The 'static' keyword allows instance-level access to variables and methods.

Explain the concept of inheritance in Java.

• Inheritance allows a superclass to inherit properties from a subclass.

• Inheritance in Java is used to define interfaces only, not classes.

• Inheritance allows a subclass to inherit properties and behaviors from a superclass, promoting code reuse and establishing a class hierarchy.

• Inheritance is a method to create new classes without any relationship to existing ones.

What is a Java interface and how is it different from an abstract class?

• A Java interface allows multiple inheritance, while an abstract class does not.

• A Java interface can have instance variables, while an abstract class cannot.

• An abstract class can be instantiated, but a Java interface cannot.

• A Java interface defines a contract for classes to implement, while an abstract class can provide some implementation and state.

What are exceptions in Java and how are they handled?

• Exceptions in Java are ignored during runtime.

• Exceptions in Java are handled using try-catch blocks to manage errors and maintain program flow.

• Exceptions in Java are only handled with if-else statements.

• Java does not support exception handling.

What is the significance of the 'main' method in a Java application?

• The 'main' method is where Java applications store their data.

• The 'main' method is the entry point for Java applications.

• The 'main' method is used for defining classes in Java.

• The 'main' method is responsible for compiling Java code.