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Core java interview questions and answers for beginners and professionals on Basics, OOPs, Methods, Overloading, Overriding, Inheritance, Polymorphism, Interfaces, Packages, Abstract classes, String handling, Exception handling, IO, Collections, Multithreading, Serialization and more.
Jul 9, 2024 · Here, we cover everything, including core Java concepts, Object-Oriented Programming (OOP), multithreading, exception handling, design patterns, Java Collections, and more, that will surely help you to crack Java interviews.
- Introduction
- CORE Java Questions For Beginners
- CORE Java Questions For Advanced Programmers
This article contains answers to some of the most important job interview questions about core Java. The answers to some of them may not be obvious so this article will help to clear things up.
Q1. Is Data Passed by Reference or by Value in Java?
Although the answer to this question is pretty simple, this question may be confusing for beginners. First, let’s clarify what the question is about: 1. Passing by value – means that we pass a copy of an objectas a parameter into a method. 2. Passing by reference – means that we pass a reference to an objectas a parameter into a method. To answer the question we have to analyze two cases. They represent two types of data that we can pass to a method: a primitive and an object. When we pass pr...
Q2. What Is the Difference Between Import and Static Imports?
We can use regular imports to import a specific class or all classes defined in a different package: We can also use them to import public nested classes of an enclosing class: However, we should be aware that the import above doesn’t import class Aitself. There are also static imports that enable us to import static members or nested classes: The effect is that we can use the static variable EMPTY_LIST without prepending the fully qualified class name, i.e. as if it was declared in the curre...
Q3. Which Access Modifiers Are Available in Java and What Is Their Purpose?
There are four access modifiers in Java: 1. private 2. default(package) 3. protected 4. public The private modifier assures that class members won’t be accessible outside the class.It can be applied to methods, properties, constructors, nested classes, but not to top-level classes themselves. Unlike the private modifier, we can apply the default modifier to all types of class members and to the class itself. We can apply default visibility by not adding any access modifier at all. If we use d...
Q1. Why Is String an Immutable Class?
We should know that String objects are treated differently than other objects by the JVM. One difference is that String objects are immutable. It means that we can’t change them once we have created them.There are several reasons why they behave that way: 1. They are stored in the string poolwhich is a special part of the heap memory. It’s responsible for saving a lot of space. 2. The immutability of the String class guarantees that its hash code won’t change. Due to that fact, Strings can be...
Q2. What Is the Difference Between Dynamic Binding and Static Binding?
Binding in Java is a process of associating a method call with the proper method body. We can distinguish two types of binding in Java: static and dynamic. The main difference between static binding and dynamic binding is that static binding occurs at compile time and dynamic binding at runtime. Static binding uses class information for binding. It’s responsible for resolving class members that are private or static and finalmethods and variables. Also, static binding binds overloaded methods...
Q3. What Is JIT?
JIT stands for “just in time”. It’s a component of the JRE that runs in the runtime and increases the performance of the application. Specifically, it’s a compiler that runs just after the program’s start. This is different from the regular Java compiler which compiles the code long before the application is started. JIT can speed up the application in different ways. For example, the JIT compiler is responsible for compiling bytecode into native instructions on the fly to improve performance...
Nov 23, 2022 · Prepare for your Java programming role with these common interview questions and answers. Learn how to reverse a string, swap numbers, check for vowels, primes, palindromes, and more.
Aug 3, 2022 · 1. Name some important features of the Java 14 release? Java 14 was released on March 17, 2020. It is a Non-LTS version. Some of the developer specific Java 14 Features are: Switch Expressions – JEP 361. Pattern matching improvements of instanceof operator – Preview Feature, JEP 305. Helpful NullPointerException Messages – JEP 358.
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Sep 8, 2021 · Beginner Java interview questions are designed to test your knowledge of basic Java principles and methods. Here are some common questions and their answers. What makes Java different from some other programming languages? Java is: Simple. Distributed. Multithreaded. Object-oriented. Platform independent. Robust. Secured. Portable.
