Member Research & Development Interview Questions and Answers

In Java, all classes inherit from Object, forming a single hierarchy regardless of tiers.

• In Java, every class implicitly extends Object, the root class.

• When class B extends A, both B and A inherit methods from Object.

• Example: If A has a method 'toString()', B can override it, but both have access to Object's methods.

• Inheritance is single in Java; B does not inherit Object separately from A.

Abstract classes are still relevant for shared state and constructor logic, despite Java 8's interface enhancements.

• Abstract classes can have instance variables, while interfaces cannot.

• Example: An abstract class 'Animal' can have a 'species' field.

• Abstract classes can provide constructors, allowing initialization of state.

• Example: 'Vehicle' abstract class can have a constructor to set 'maxSpeed'.

• Interfaces are limited to method signatures and default/static methods.

• Abstract ...read more

Implementing interfaces vs abstract classes in real life

• Interfaces are useful when implementing multiple inheritance in Java

• Abstract classes are useful when creating a base class with some implementation

• Example of interface: implementing Runnable interface in a class to create a thread

• Example of abstract class: creating a base class for different types of vehicles

Singleton pattern ensures only one instance of a class is created and provides a global point of access to it.

• Private constructor to restrict object creation

• Private static instance variable to hold the single instance

• Public static method to get the instance

• Lazy initialization or eager initialization

• Thread-safe implementation using synchronized keyword or static block

• Examples: java.lang.Runtime, java.awt.Desktop, java.util.Calendar

SOLID design principles are a set of guidelines for writing maintainable and scalable code.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: A class should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: A client should not be forced to depend on methods it does not use.

• D - Dependency Invers...read more

The laws of thermodynamics describe the behavior of energy in physical systems.

• The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted.

• The second law of thermodynamics states that the entropy of an isolated system always increases over time.

• The third law of thermodynamics states that as the temperature approaches absolute zero, the entropy of a system approaches a minimum value.

• Thermodynamics is used in various fields s...read more