Design Pattern
Thursday, June 13, 2024 in Java Interview Questions
Design Pattern Singleton Pattern A creational pattern that restricts the instantiation of a class to a single instance eg. beans in IoC Container Decorator Pattern A structural pattern that allows behavior to be added to an individual object, …
SOLID Principle
Thursday, June 13, 2024 in Java Interview Questions
SOLID Principle Single Responsibility Principle A class should have only one reason to change Open Closed Principle Software entities should be open for extension, but closed for modification Liskov Substitution Principle Objects of a superclass …
I/O
Thursday, June 13, 2024 in Java Interview Questions
I/O Java I/O is built around the concept of streams, which are sequences of data Type Byte Streams InputStream and its subclasses OutputStream and its subclasses Character Streams Reader and its subclasses Writer and its subclasses Buffered streams …
Multithreading
Thursday, June 13, 2024 in Java Interview Questions
Multithreading Multithreading is a Java feature that allows concurrent execution of two or more threads for maximum utilization of the CPU Process vs Thread A process is an executing program. It has its own memory space and resources A thread is a …
Functional Interface
Thursday, June 13, 2024 in Java Interview Questions
Functional Interface An interface that contains exactly one abstract method @FunctionalInterface Used to mark an interface as a functional interface Usage with Lambda Expressions Lambda expressions provide a simple way to implement functional …
Stream
Thursday, June 13, 2024 in Java Interview Questions
Stream An abstraction that allows you to process sequences of elements in a functional style Stream Operations Intermediate Operations eg. filter Terminal Operations eg. toList public class Main { public static void main(String[] args) { …
Generic
Thursday, June 13, 2024 in Java Interview Questions
Generic Generics enable types (classes and interfaces) to be parameters when defining classes, interfaces, and methods Pros Stronger type checks at compile time No casting needed Ability to implement generic algorithms Declare Generics Generic class …
Checked Exceptions vs Unchecked Exceptions
Thursday, June 13, 2024 in Java Interview Questions
Checked Exceptions vs Unchecked Exceptions Checked Exceptions Unchecked Exceptions Definition Exceptions that are checked at compile-time Exceptions that occur at runtime and are not checked at compile-time Handling Requirement Must be either caught …
== vs equals vs hashCode
Thursday, June 13, 2024 in Java Interview Questions
== vs equals vs hashCode == equals hashCode Definition Compares references for objects, values for primitives Compares the contents of two objects Returns a hash code value for the object Good Practice Always override equals() when a class’s …
String vs StringBuilder vs StringBuffer
Thursday, June 13, 2024 in Java Interview Questions
String vs StringBuilder vs StringBuffer String StringBuilder StringBuffer Mutability Immutable Mutable Mutable Thread Safety Thread-safe Not thread-safe Thread-safe Use Case Suitable for values that won’t change Best for strings that are …