Java Interview | Questions & Answers (100 %Score) Latest Updated 2024/2025
Comprehensive Questions A+ Graded Answers | With Expert Solutions
How to delete a character in a String - Because Strings in Java are immutable. You'll have to create a new
string removing the character you don't want.
String newstr = str.substring(0, idx) + str.substring(idx + 1);
public String removeChar(String str, Integer n) {
String front = str.substring(0, n);
String back = str.substring(n+1, str.length());
return front + back;
}
What is Object Oriented Programming - Object-oriented programming (OOP) is a programming language
model organized around objects rather than "actions" and data rather than logic.
The first step in OOP is to identify all the objects the programmer wants to manipulate and how they
relate to each other, an exercise often known as data modeling.
What are be benefits of Object-Oriented Programming - Improved code reuse.
Improved software maintainability.
Faster development.
4 major principles that make a
language object-oriented. - Encapsulation, Data Abstraction, Polymorphism and Inheritence.
Describe the software development lifecycle - Communication, System concept development,
What is multithreading? - Multithreading is a process of executing multiple threads simultaneously. Its
main advantage is:
, Threads share the same address space.
Thread is lightweight.
Cost of communication between process is low.
What is thread? - A thread is a lightweight subprocess.It is a separate path of execution.It is called
separate path of execution because each thread runs in a separate stack frame.
What is difference between JDK,JRE and JVM? - JVM is an acronym for Java Virtual Machine, it is an
abstract machine which provides the runtime environment in which java bytecode can be executed. It is
a specification.
JRE stands for Java Runtime Environment. It is the implementation of JVM.
JDK is an acronym for Java Development Kit. It physically exists. It contains JRE + development tools.
How many types of memory areas are allocated by JVM? - Class(Method) Area
Heap
Stack
Program Counter Register
Native Method Stack
What is the main difference between Java platform and other platforms? - The Java platform differs
from most other platforms in the sense that it's a software-based platform that runs on top of other
hardware-based platforms.It has two components:
Runtime Environment
API(Application Programming Interface)
What gives Java its 'write once and run anywhere' nature? - The bytecode. Java is compiled to be a byte
code which is the intermediate language between source code and machine code. This byte code is not
platform specific and hence can be fed to any platform.
Comprehensive Questions A+ Graded Answers | With Expert Solutions
How to delete a character in a String - Because Strings in Java are immutable. You'll have to create a new
string removing the character you don't want.
String newstr = str.substring(0, idx) + str.substring(idx + 1);
public String removeChar(String str, Integer n) {
String front = str.substring(0, n);
String back = str.substring(n+1, str.length());
return front + back;
}
What is Object Oriented Programming - Object-oriented programming (OOP) is a programming language
model organized around objects rather than "actions" and data rather than logic.
The first step in OOP is to identify all the objects the programmer wants to manipulate and how they
relate to each other, an exercise often known as data modeling.
What are be benefits of Object-Oriented Programming - Improved code reuse.
Improved software maintainability.
Faster development.
4 major principles that make a
language object-oriented. - Encapsulation, Data Abstraction, Polymorphism and Inheritence.
Describe the software development lifecycle - Communication, System concept development,
What is multithreading? - Multithreading is a process of executing multiple threads simultaneously. Its
main advantage is:
, Threads share the same address space.
Thread is lightweight.
Cost of communication between process is low.
What is thread? - A thread is a lightweight subprocess.It is a separate path of execution.It is called
separate path of execution because each thread runs in a separate stack frame.
What is difference between JDK,JRE and JVM? - JVM is an acronym for Java Virtual Machine, it is an
abstract machine which provides the runtime environment in which java bytecode can be executed. It is
a specification.
JRE stands for Java Runtime Environment. It is the implementation of JVM.
JDK is an acronym for Java Development Kit. It physically exists. It contains JRE + development tools.
How many types of memory areas are allocated by JVM? - Class(Method) Area
Heap
Stack
Program Counter Register
Native Method Stack
What is the main difference between Java platform and other platforms? - The Java platform differs
from most other platforms in the sense that it's a software-based platform that runs on top of other
hardware-based platforms.It has two components:
Runtime Environment
API(Application Programming Interface)
What gives Java its 'write once and run anywhere' nature? - The bytecode. Java is compiled to be a byte
code which is the intermediate language between source code and machine code. This byte code is not
platform specific and hence can be fed to any platform.
