Java Basic Knowledge

Introduction

Java is the most popular, high-level, class-based, object-oriented programming language. It was developed by James Gosling at Sun Microsystem. It was released in May 1995.

5 primary goals in the creation of the Java language

1. It must be simple, object-oriented, and familiar.

2. It must be robust(they can handle unexpected events and errors without crashing or causing harm) and secure.

3. It must be architecture-neutral(This means that Java code can be compiled on one platform and executed on another platform without modification) and portable.

4. It must execute with high performance.

5. It must be interpreted(convert high-level program statements into a machine code comprising source code, threaded(a lightweight process), and dynamic.

There are four editions of Java.

• Java SE(Standard Edition) is used for developing desktop and server-side applications.

• Java EE(Enterprise Edition) is used for enterprise applications.

• Java ME(Micro Edition) targeting environment with limited edition.

• JavaFX(for creating and delivering desktop applications).

Note: Officially, There is no core Java and advanced Java. There is only java. But for learning purposes, we are divided into two parts: Core Java and Advanced Java. Core Java is a part of JavaSE and advanced Java is a part of JavaSE and JavaEE.

Core Java or JavaSE

In core Java, we learn the basics of Java.

• Compiler(Java compiler converts Unicode into bytecode).

• JVM(Java Virtual Machine).

• JDK(Java Development kit)

• Identifier.

• Keywords.

• Literals.

• Data Types

• Variables.

• Type conversions.

• Operators.

• Java library.

• Java notations.

• JShell(Java shell).

• Statements in Java.

• OOPs(Object Oriented principles) Encapsulation, Abstraction, Inheritance, Polymorphism. These are the most important topics.

• Class.

• Object.

• Constructor.

• Method

• Arrays.

• Method overloading.

• Method overriding.

• Access Modifiers(private,protected,public,default)

• Upcasting.

• Downcasting.

• Interface.

• packages

• String handling

• Synchronization.

• Wrapper classes.

• Exception Handling(most important).

• Java streams

• Network programming

• Collections Framework(most important topic).

• Multithreading.

• Lambda expression.

Above all topics are the most important. Before start learning advanced Java we have to complete it.

Advanced Java or JavaSE and JavaEE

• JDBC(Java DataBase Connectivity).

• Servlets.

• Servlets Listeners.

• Filters.

• JSP(Java Server Pages).

• JSP using Java Beans.

• JSP EL (JSP Expression Language).

• JSTL(Standard Tag Library).

• MVC(Model View Controller )By using Java Bean, JSP & Servlet.

• Reflection API (Application Programming Interface).

All topics are important for clearing any interview. If you remember all these topics then your interview is like a piece of cake.

Reference: https://en.wikipedia.org/wiki/Java_(programming_language)

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Thanks. Happy learning.