Java Programming Tutorials - Java Programiz - Androidpro.in

This Java programming for beginners course will help you learn basics of Java and advanced concepts.

JAVA PROGRAMS EXAMPLE

What is Java?

Java is a general-purpose, class-based, object-oriented programming language designed for having lesser implementation dependencies. It is a computing platform for application development. Java is fast, secure, and reliable, therefore. It is widely used for developing Java applications in laptops, data centers, game consoles, scientific supercomputers, cell phones, etc.

Java runs on 3 billion devices worldwide, which makes Java one of the most popular programming languages. Java is developed at Sun Microsystems in 1995.

Modeled after C++, the Java language was designed to be small, simple, and portable across platforms and operating systems, both at the source and at the binary level (more about this later).

 

  • The Java programming language is a high-level, object-oriented and general-purpose computer programming language.
  • Java is similar to C++, but simplified to eliminate language features that cause common programming errors.
  • You can use Java to write computer applications that play games, store data or do any of the thousands of other things computer software can do.
  •  It is intended to let application developers "write once, run anywhere" (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for recompilation.

 

  1. Java Hello World
  2. Java JVM, JRE and JDK
  3. Java Variables
  4. Java String 
  5.  Java Data Types

Where is Java used for?

Here are some important Java applications:

  • It is used for developing Android Apps
  • Helps you to create Enterprise Software
  • Wide range of Mobile java Applications
  • Scientific Computing Applications
  • Use for Big Data Analytics
  • Java Programming of Hardware devices
  • Used for Server-Side Technologies like Apache, JBoss, GlassFish, etc.

 

History of Java Programming Language

Here are important landmarks from the history of the Java language:

  • The Java language was initially called OAK.
  • Originally, it was developed for handling portable devices and set-top boxes. Oak was a massive failure.
  • In 1995, Sun changed the name to “Java” and modified the language to take advantage of the burgeoning www (World Wide Web) development business.
  • Later, in 2009, Oracle Corporation acquired Sun Microsystems and took ownership of three key Sun software assets: Java, MySQL, and Solaris.

 

Java Versions

Here are a brief history of all the Java versions with its release date.

Java Versions

Release Date

JDK Alpha and Beta

1995

JDK 1.0

23rd Jan 1996

JDK 1.1

19th Feb 1997

J2SE 1.2

8th Dec 1998

J2SE 1.3

8th May 2000

J2SE 1.4

6th Feb 2002

J2SE 5.0

30th Sep 2004

Java SE 6

11th Dec 2006

Java SE 7

28th July 2011

Java SE 8

18th Mar 2014

Java SE 9

21st Sep 2017

Java SE 10

20th Mar 2018

JAVA SE 11

25th Sep 2018

JAVA SE 12

19th Mar 2019

JAVA SE 13

17th Sep 2019

JAVA SE 14

17th Mar 2020

JAVA SE 15

15th Sep 2020 (latest Java Version)

 

Java Features

Here are some important Java features:

  • It is one of the easy-to-use programming languages to learn.
  • Write code once and run it on almost any computing platform.
  • Java is platform-independent. Some programs developed in one machine can be executed in another machine.
  • It is designed for building object-oriented applications.
  • It is a multithreaded language with automatic memory management.
  • It is created for the distributed environment of the Internet.
  • Facilitates distributed computing as its network-centric.

v  Simple

v  Secure

v  Portable

v  Object-oriented

v  Robust

v  Multithreaded

v  Architecture-neutral

v  Interpreted

v  High performance

v  Distributed

v  Dynamic

 

Simple:

  • Java is Easy to write and more readable and eye catching.
  • Java has a concise, cohesive set of features that makes it easy to learn and use.
  • Most of the concepts are drew from C++ thus making Java learning simpler.

Secure:

  • Java program cannot harm other system thus making it secure.
  • Java provides a secure means of creating Internet applications.
  • Java provides secure way to access web applications.

Portable:

  • Java programs can execute in any environment for which there is a Java run-time system.(JVM)
  • Java programs can be run on any platform (Linux,Window,Mac)
  • Java programs can be transferred over world wide web (e.g applets)

Object-oriented:

  • Java programming is object-oriented programming language.
  • Like C++ java provides most of the object oriented features.
  • Java is pure OOP. Language. (while C++ is semi object oriented)

Robust:

Java encourages error-free programming by being strictly typed and performing run-time checks.

Multithreaded:

Java provides integrated support for multithreaded programming.

Architecture-neutral:

Java is not tied to a specific machine or operating system architecture.
Machine Independent i.e Java is independent of hardware .

Interpreted:

Java supports cross-platform code through the use of Java bytecode.
Bytecode can be interpreted on any platform by JVM.

High performance:

Bytecodes are highly optimized.
JVM can executed them much faster .

Distributed:

Java was designed with the distributed environment.
Java can be transmit,run over internet.

Dynamic:

Java programs carry with them substantial amounts of run-time type information that is used to verify and resolve accesses to objects at run time.

 

Components Of Java Programming Language

A Java Programmer writes a program in a human-readable language called Source Code. Therefore, the CPU or Chips never understand the source code written in any programming language.

These computers or chips understand only one thing, which is called machine language or code. These machine codes run at the CPU level. Therefore, it would be different machine codes for other models of CPU.

However, you need to worry about the machine code, as programming is all about the source code. The machine understands this source code and translates them into machine understandable code, which is an executable code.


Java Development kit (JDK)

JDK is a software development environment used for making applets and Java applications. The full form of JDK is Java Development Kit. Java developers can use it on Windows, macOS, Solaris, and Linux. JDK helps them to code and run Java programs. It is possible to install more than one JDK version on the same computer.

Why use JDK?

Here are the main reasons for using JDK:

  • JDK contains tools required to write Java programs and JRE to execute them.
  • It includes a compiler, Java application launcher, Appletviewer, etc.
  • Compiler converts code written in Java into byte code.
  • Java application launcher opens a JRE, loads the necessary class, and executes its main method


.

    Java Virtual Machine (JVM):

    Java Virtual Machine (JVM) is an engine that provides a runtime environment to drive the Java Code or applications. It converts Java bytecode into machine language. JVM is a part of the Java Run Environment (JRE). In other programming languages, the compiler produces machine code for a particular system. However, the Java compiler produces code for a Virtual Machine known as Java Virtual Machine.

    Why JVM?

    Here are the important reasons of using JVM:

    • JVM provides a platform-independent way of executing Java source code.
    • It has numerous libraries, tools, and frameworks.
    • Once you run a Java program, you can run on any platform and save lots of time.
    • JVM comes with JIT (Just-in-Time) compiler that converts Java source code into low-level machine language. Hence, it runs faster than a regular application.


      Java Runtime Environment (JRE)

      JRE is a piece of software that is designed to run other software. It contains the class libraries, loader class, and JVM. In simple terms, if you want to run a Java program, you need JRE. If you are not a programmer, you don’t need to install JDK, but just JRE to run Java programs.


      Why use JRE?

      Here are the main reasons of using JRE:

      • JRE contains class libraries, JVM, and other supporting files. It does not include any tool for Java development like a debugger, compiler, etc.
      • It uses important package classes like math, swing, util, lang, awt, and runtime libraries.
      • If you have to run Java applets, then JRE must be installed in your system.


      Different Types of Java Platforms

      There are four different types of Java programing language platforms:

      1. Java Platform, Standard Edition (Java SE): Java SE’s API offers the Java programming language’s core functionality. It defines all the basis of type and object to high-level classes. It is used for networking, security, database access, graphical user interface (GUI) development, and XML parsing.

      2. Java Platform, Enterprise Edition (Java EE): The Java EE platform offers an API and runtime environment for developing and running highly scalable, large-scale, multi-tiered, reliable, and secure network applications.

      3. Java Programming Language Platform, Micro Edition (Java ME): The Java ME platform offers an API and a small-footprint virtual machine running Java programming language applications on small devices, like mobile phones.

      4. Java FX: JavaFX is a platform for developing rich internet applications using a lightweight user-interface API. It user hardware-accelerated graphics and media engines that help Java take advantage of higher-performance clients and a modern look-and-feel and high-level APIs for connecting to networked data sources.

      To understand Java programming language, we need to understand some basic concept of how a computer program can run a command and execute the action.


      How Java Virtual Machine works?

      By using Java Virtual Machine, this problem can be solved. But how it works on different processors and O.S. Let’s understand this process step by step.



      Step 1) The code to display the addition of two numbers is System.out.println(1+2), and saved as a .java file.

      Step 2) Using the java compiler the code is converted into an intermediate code called the bytecode. The output is a .class file.

      Step 3) This code is not understood by any platform, but only a virtual platform called the Java Virtual Machine.

      Step 4) This Virtual Machine resides in the RAM of your operating system. When the Virtual Machine is fed with this bytecode, it identifies the platform it is working on and converts the bytecode into the native machine code.

      While working on your PC or browsing the web, whenever you see either of these icons, be assured the java virtual machine is loaded into your RAM. But what makes Java lucrative is that code, once compiled, can run not only on all PC platforms but also on mobiles or other electronic gadgets supporting Java.