IBM Senior Java Developer Interview Questions and Answers

final is a keyword in Java used to declare constants, while finally is a block used in exception handling to ensure code is executed regardless of an exception.

• final keyword is used to declare constants in Java

• final variables cannot be reassigned once initialized

• finally block is used in exception handling to ensure code is executed regardless of an exception

• finally block is often used to release resources like closing

Developed a web application for a financial institution to manage customer accounts and transactions.

• Used Java Spring framework for backend development

• Implemented RESTful APIs for communication between frontend and backend

• Utilized Hibernate for database interaction

• Integrated third-party payment gateway for transactions

Garbage collection in Java is the process of automatically reclaiming memory by destroying unused objects.

• Garbage collection is performed by the JVM to free up memory occupied by objects that are no longer needed.

• It involves identifying and deleting objects that are no longer reachable by any part of the program.

• Java provides automatic garbage collection, so developers do not have to manually manage memory allocation a...read more

The first statement creates a string literal in the string pool, while the second statement creates a new string object in the heap memory.

• String s = "xyz" creates a string literal in the string pool.

• String s = new String("xyz") creates a new string object in the heap memory.

• Using String s = new String("xyz") can lead to unnecessary memory usage.

JVM is the virtual machine that runs Java programs, JRE is the runtime environment for Java programs, and JDK is the development kit for creating Java programs.

• JVM (Java Virtual Machine) is the virtual machine that runs Java bytecode and converts it into machine code.

• JRE (Java Runtime Environment) is the environment in which Java programs are executed. It includes JVM, libraries, and other necessary components.

• JDK (Jav...read more

The public static void main method is the entry point of a Java program, where execution begins.

• It must be declared as public so that it can be accessed from outside the class.

• It must be declared as static so that it can be called without creating an instance of the class.

• It must have a return type of void, indicating that it does not return any value.

• It takes an array of strings (String[] args) as a parameter, which a...read more

final is a keyword used to declare constants, finally is a block used in exception handling, and finalize is a method used for cleanup.

• final keyword is used to declare constants that cannot be changed

• finally block is used in exception handling to ensure a piece of code is always executed

• finalize method is used for cleanup operations before an object is garbage collected

HashSet is a collection class in Java that stores unique elements using a hash table.

• Uses hashing to store elements

• Does not maintain insertion order

• Allows null values

• Implements Set interface

ArrayList is a resizable array implementation in Java.

• ArrayList is a class in Java that implements the List interface.

• It allows dynamic resizing of the array, unlike regular arrays.

• Elements can be added, removed, or accessed using index.

• Example: ArrayList names = new ArrayList<>();