Introduction to Java Programming- Java Programming Tutorials for beginners

Java is ...
Old - maybe not old enough
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1.0 What is Java ?
– Java is a programming language and a platform.
– Java is a high level, robust, object-oriented and secure
programming language.
– Platform: Any hardware or software environment in which
a program runs, is known as a platform.
■ Since Java has a runtime environment (JRE) and API, it is called
a platform.

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Java Example
//File name : simple.java
import java.io.*;
class Simple
{
public static void main(String args[])
{
System.out.println("Hello Java");
}
}

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Java Applications
■ We know that Java is the “King of all programming
languages”.
■ Since its foundation, this language has become a
backbone for billions of devices and applications.
■ This language is continually ranked first in the rankings
of software developers as the best choice of
programming languages.
■ Java is used in the majority of applications, from
mobile phones to enterprise servers and computing
platforms.

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Java Applications
■ Currently, about 3 billion mobile phones are implemented in
Java, as well as about 125 million TV sets and each Blu-ray
player use Java.
■ Every big organization uses Java in one way or another.
■ More than 64,000 companies are using Java in the United
States.
■ For example, Google uses Java to build and develop Google
Docs applications.
■ According to Sun, 3 billion devices run Java.
– There are many devices where Java is currently used.

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Java Applications
■ You would be wondering why Java is so popular and where it is exactly used.
■ Below is the Java applications list:
1) Desktop GUI Applications
2) Mobile Applications
3) Enterprise Applications
4) Scientific Applications
5) Web-based Applications
6) Embedded Systems
7) Big Data Technologies
8) Distributed Applications
9) Cloud-based Applications
10) Web servers and Application servers
11) Software Tools
12) Gaming Applications

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Java Applications …
1. Desktop GUI (Graphical User Interface) Applications
■ Desktop applications can be easily developed using Java.
– We use APIs like AWT, Swing, JavaFX to build these applications.
■ AWT (Abstract Windowing Toolkit) is an interface used to develop window-based applications
in Java.
– It is “not totally Java-based” as it uses window user interface functionalities such as a
menu, button, list, etc.
■ Swing is a GUI widget toolkit, which uses AWT and provides certain advanced components
like trees, tables, scroll panes, tabbed panels and, lists.
– Swing is” totally java-based” and uses Swing packages of Java to develop applications. It
responds to all the mouse-click events, key entries, etc.,
■ JavaFX is a modern way to develop a desktop application in Java, it is graph-based and totally
different from AWT and Swings.
■ Examples of desktop GUI applications are Acrobat Reader, ThinkFree, Media Player,
Antiviruses, etc.

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2. Mobile Applications
■ A mobile application is an application created for mobile phones and tablets.
– In today’s era, the majority of phones and smart devices have Android OS and Android
development is not possible without Java.
– Java Micro Edition (Java ME or J2ME) is a popular cross-platform framework that is
used to build applications that run across all feature phones and smartphones.
■ Moreover, Java is compatible with AndroidStudio and Kotlin.
■ Now, you must be thinking why only for Android mobile app development?
– The reason is that Java compiler compiles the Java classes into bytecode and this
bytecode runs on Dalvik Virtual Machine (DVM), which is a specialized virtual machine
(VM) for Android.
■ Examples of mobile applications are Photo and video gallery apps, Simple Calendar, Netflix,
Tinder, QRReader, Google Earth, Uber, etc.

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3. Enterprise Applications
■ An enterprise application is a large software system which operates in a corporate
environment, to satisfy the needs of an organization, rather than of individual users.
■ Java becomes the first choice for the development of enterprise applications because
of its robust features that match the requirements for the same.
– In today’s era, most of the enterprise organizations are based on the applications
of Java only because it is the most secure, powerful, scalable language.
■ Oracle Corporation claims that “about 97% of enterprise applications use Java for
development of large-scale software”.
■ Java EE (Java Enterprise Edition) is an API that is used to provide the tools necessary
to develop large-scale, multi-tiered, scalable, reliable, distributed and secured
network applications in enterprises.

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3. Enterprise Applications …
■ Java fulfills the most essential need of these enterprises, which is security, as Java runs inside
the JVM (Java Virtual Machine), which verifies the bytecode coming from the external systems,
which ultimately prevents the security breaches.
– This is the reason why most of the banking applications are developed on the Java
platform.
■ Moreover, Java improves the performance of these applications, as it comes with strong
memory management, which automatically deletes the unused memory.
■ Applications of Java can easily be made scalable in order to increase the number of users on
the enterprise application site.
■ Companies like Naukri, Jabong, Google, Myntra, Flipkart, Trivago, ibibo, TripAdvisor, Spotify,
Uber, TCS, Infosys, HCL, Wipro, Pinterest, eBay, etc. use Java.
■ Examples of enterprise applications are Business corporations, schools, banks, ERP
(Enterprise Resource Planning) and CRM (Customer Resource Management) systems, clubs,
charities, governments, interest-based user groups, etc.

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4. Scientific Applications
■ A scientific application is an application that affects real-world activities using mathematics.
– Java supports the development of scientific applications, because of its powerful features.
■ Java becomes the best choice for writing scientific applications involving scientific calculations and
mathematical operations.
– It provides a fast, secure and highly portable environment to these applications, which is the basic
requirement for these applications.
■ It has powerful mathematical calculations which have to give the same results on different platforms, this
makes the choice for the developers to opt Java for scientific applications.
■ MATLAB (Mathematical Laboratory) which is one of the most popular scientific applications, uses Java for
developing both front-end (interactive user-interface) and back-end (a core part of the system).
■ The front-end and back-end of the scientific applications are both based on Java.
– For the front-end, Java provides struts, JSP (Java Server Pages), servlets.
– For the back-end, core Java can be used in servlets.
■ Examples of scientific applications are applications related to research, science, medical science, space,
aeronautics, etc.

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5. Web-based Applications
■ A web application is a client-server program that is delivered on the Internet through a browser interface.
■ Java supports the development of web-applications with the help of servlets, struts, JSP (Java Server
Pages) and JSF (Java Server Faces), Spring, Hibernate and web-servers like Apache Tomcat, Apache HTTP
web-server, Resin, adobe JRun, etc.
– With the help of these technologies, we can develop any kind of web-based application.
■ Servlets and JSPs are the server-side components that help to develop the business logic of the web
application.
– JSP is an extension of the Servlet as it has more features as compared to the servlet.
■ E-commerce web applications also use Java with the help of open-source eCommerce platforms, such as
Broadleaf.
■ Java provides easy coding and high security which enables the development of a large number of
applications for health, social security, education, and insurance.
■ Examples of web-based applications are irctc.co.in, online forms, shopping carts, Gmail, Google Sheets,
Google Slides and many more.

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6. Embedded Systems
■ An embedded system, also known as an integrated system, is a combination of many small computing units
that assemble together to perform dedicated functions for the larger systems.
■ Embedded systems are present everywhere.
– Don’t believe it? Most of us use them without knowing.
■ For example, a motor system, entertainment and multimedia in a car, E-commerce, wireless
communication, mobile computing and networking use an embedded system.
■ Embedded systems use Java for development.
– Originally, Java was designed for the purpose of developing embedded systems.
■ Java shows how efficient its platform is, for which there is a need of just 130 KBs to use it on smart cards or
sensors.
– Java is fast which can be important when using low-power/low-speed processors, and its robustness
which means handles exceptions safely.
■ SIM (Subscriber Identity Module) cards in our phones have been running a variant of the JVM (Java Card) for
nearly 20 years.
■ Other devices like BlueRay Disc players, utility meters and televisions use Java technology.
– According to Oracle Corporation, “100% of Blu-ray Disc Players and 125 million TV devices use Java”.

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7. Big Data Technologies
■ The term big data is defined as “extremely large and complex datasets that may be analyzed to extract
patterns, trends, and useful information.
– It is one of the most popular topics in the world of the latest technology.
– Java is the perspective of big data.
– Today, many developers are switching their careers to Big Data Technology.
■ An open-source framework, called Hadoop, associated with big data, is written in Java.
– Moreover, the Automatic Garbage Collection and strong memory management give it higher
priority over the other programming languages.
■ Many prominent big data technologies like Apache Hadoop, Apache Spark, Apache Mahout, etc. are
the sub-projects of Java.
– Also, the most powerful programming languages like Scala (Scalable Language), a pure object-
oriented language, is based on Java.
– Scala programs are easily convertible into bytecode; which can run on the JVM.
■ Hadoop and other big data technologies are also using Java in one way or the other.
– For example, Apache’s Java-based HBase and Accumulo (open source), and ElasticSearch as well.

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8. Distributed Applications
■ A distributed application is an application or software that executes or runs on
multiple computers within a network.
■ Distributed applications or systems have many common requirements that occur
especially because of the distributed and dynamic nature of the platforms they
operate on.
– Java offers options to realize these applications.
■ RMI (Remote Procedure Invocation) and CORBA (Common Object Request Broker
Architecture) are the APIs to develop distributed applications.
■ The Jini (Java Intelligent Networking Infrastructure) gives an infrastructure to
provide, register, and find distributed services based on its specifications.
– An essential part of Jini is JavaSpaces, that supports distribution, persistence,
and migration of objects in a distributed environment.

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9. Cloud-based Applications
■ Cloud computing means on-demand delivery of IT resources via the Internet, including storage, servers,
databases, networking, and software with a pay-as-you-go pricing model.
– It provides a solution for IT infrastructure at a low cost, as we can save files on remote databases and
retrieve them on demand.
■ No doubt you’re curious how Java programming fits into the cloud computing picture.
■ Java has long been the programming language that provides a structure for web applications, and now it
has reached cloud applications, because of its distributed nature.
■ Java provides us with features that can help us build applications used in SaaS (Software-as-a-service),
IaaS (Infrastructure-as-a-service) and PaaS (Platform-as-a-service) development.
■ There are many Java cloud development tools.
– For example, Oracle Java cloud service provides a platform to develop and configure the Oracle
servers.
■ Java can serve the companies to build their applications remotely or help them share data with others,
according to their needs.

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10. Web Servers and Application Servers
■ A web server is a computer program that uses HTTP (Hypertext Transfer Protocol) and other
protocols, to store, process, and respond to client requests made over WWW (World Wide Web).
– A web server is a system that runs websites and delivers web pages to users.
■ An application server (or app server) is a software framework that stores the business logic for
an application program and handles all operations between the client-end and the back-end of
organizations.
– It is not limited to HTTP but can do a bunch of other stuff.
■ Java ecosystem contains multiple Java web servers and application servers.
■ Java provides web servers including Apache Tomcat, Simple, Jo!, Rimfaxe Web Server (RWS)
Apache HTTP server, Resin, Adobe JRun, and Project Jigsaw.
■ WebLogic, GlassFish, WildFly, WebSphere, and JBoss EAP occupy commercial application server
space.

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11. Software Tools
■ A software tool is a set of computer programs that developers use to develop, analyze, maintain, debug, or
support other applications and programs.
– Many developers use Java to write and develop useful software tools.
■ Examples of software tools are Eclipse, IntelliJ Idea, and NetBeans IDE.
12. Gaming Applications
■ Java proves to be one of the best platforms for developing 2-Dimensional games.
– Today almost every person has an Android phone that has Android games in it.
– Android games cannot be built without Java.
■ Java supports jMonkeyEngine which is the most powerful open-source 3D-Engine and has the capacity to
design 3-Dimensional games.
■ Android games use Java as a primary language because Java supports the Dalvik Virtual Machine (DVM)
which is specially designed to run on the Android platform.

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Java Platforms / Editions
■ There are 4 platforms or editions of Java:
1) Java SE (Java Standard Edition)
■ It is a Java programming platform.
– It includes Java programming APIs such as java.lang, java.io, java.net, java.util,
java.sql, java.math etc.
– It includes core topics like OOPs, String, Regex, Exception, Inner classes,
Multithreading, I/O Stream, Networking, AWT, Swing, Reflection, Collection,
etc.
2) Java EE (Java Enterprise Edition)
■ It is an enterprise platform which is mainly used to develop web and enterprise
applications.
– It is built on the top of the Java SE platform.
– It includes topics like Servlet, JSP, Web Services, EJB, JPA, etc.

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Java Platforms / Editions …
3) Java ME (Java Micro Edition)
■ It is a micro platform which is mainly used to develop mobile applications.
4) JavaFX
■ It is used to develop rich internet applications.
– It uses a light-weight user interface API.

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1.1 History of Java
■ The history of Java is very interesting.
– Java was originally designed for interactive television, but it was too advanced
technology for the digital cable television industry at the time.
– The history of java starts with Green Team.
– Java team members (also known as Green Team), initiated this project to develop a
language for digital devices such as set-top boxes, televisions, etc.
– However, it was suited for internet programming.
– Later, Java technology was incorporated by Netscape.
■ The principles for creating Java programming were "Simple, Robust, Portable, Platform-
independent, Secured, High Performance, Multithreaded, Architecture Neutral, Object-
Oriented, Interpreted and Dynamic".
■ James Gosling - founder of java
– Currently, Java is used in internet programming, mobile devices, games, e-business
solutions, etc.

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1.1 History of Java …
■ There are given the significant points that describe the history of Java.
1) James Gosling, Mike Sheridan, and Patrick Naughton initiated the
Java language project in June 1991.
■ The small team of sun engineers called Green Team.
2) Originally designed for small, embedded systems in electronic
appliances like set-top boxes.
3) Firstly, it was called "Greentalk" by James Gosling, and file extension
was .gt.
4) After that, it was called Oak and was developed as a part of the
Green project.

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Why Java named "Oak"?
5) Why Oak?
– Oak is a symbol of strength and chosen as a national tree of many
countries like U.S.A., France, Germany, Romania, etc.
6) In 1995, Oak was renamed as "Java" because it was already a
trademark by Oak Technologies.

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Why Java Programming named "Java"?
7) Why had they chosen java name for java language?
– The team gathered to choose a new name.
– The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA", etc.
– They wanted something that reflected the essence of the technology: revolutionary, dynamic,
lively, cool, unique, and easy to spell and fun to say.
– According to James Gosling, "Java was one of the top choices along with Silk".
– Since Java was so unique, most of the team members preferred Java than other names.
8) Java is an island of Indonesia where first coffee was produced (called java coffee).
9) Notice that Java is just a name, not an acronym.
10) Initially developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle
Corporation) and released in 1995.
11) In 1995, Time magazine called Java one of the Ten Best Products of 1995.
12) JDK 1.0 released in(January 23, 1996).

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1.2 Java Version History …
■ Many java versions have been released till now.
– The current stable release of Java is Java SE 10.
1) JDK Alpha and Beta (1995)
2) JDK 1.0 (23rd Jan 1996)
3) JDK 1.1 (19th Feb 1997)
4) J2SE 1.2 (8th Dec 1998)
5) J2SE 1.3 (8th May 2000)
6) J2SE 1.4 (6th Feb 2002)
7) J2SE 5.0 (30th Sep 2004)
8) Java SE 6 (11th Dec 2006)
9) Java SE 7 (28th July 2011)
10) Java SE 8 (18th March 2014)
11) Java SE 9 (21st Sep 2017)
12) Java SE 10 (20th March 2018)
13) Java SE 11 (September 25, 2018)
14) Java SE 12 (March 19, 2019)
16) Java SE 14 (March 17, 2020)

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1.3 Features of Java
■ The primary objective of Java
programming language creation was
to make it portable, simple and
secure programming language.
– Apart from this, there are also
some excellent features which
play an important role in the
popularity of this language.
– The features of Java are also
known as java buzzwords.

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1.3 Features of Java …
■ A list of most important features of
Java language is given below.
1)Simple
2)Object-Oriented
3)Portable
4)Platform
independent
5)Secured
6)Robust
7)Architecture
neutral
8)Interpreted
9)High Performance
10)Multithreaded
11)Distributed
12)Dynamic

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1.3. Features of Java …
1.) Simple
– Java is very easy to learn, and its syntax is simple, clean and easy to
understand.
– According to Sun, Java language is a simple programming language because:
■ Java syntax is based on C++ (so easier for programmers to learn it
after C++).
■ Java has removed many complicated and rarely-used features, for
example, explicit pointers, operator overloading, etc.
■ There is no need to remove unreferenced objects because there is an
Automatic Garbage Collection in Java.

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2.) Object-oriented
– Java is an object-oriented programming language.
■ Everything in Java is an object.
■ Object-oriented means we organize our software as a combination of different types of objects that
incorporates both data and behavior.
– Object-oriented programming (OOPs) is a methodology that simplifies software development
and maintenance by providing some rules.
– Basic concepts of OOPs are:
 Object
 Class
 Inheritance
 Polymorphism
 Abstraction
 Encapsulation

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3.) Platform Independent

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– Java is platform independent because it is different from other
languages like C, C++, etc. which are compiled into platform specific
machines while Java is a write once, run anywhere language.
■ A platform is the hardware or software environment in which a program runs.
– There are two types of platforms software-based and hardware-based.
■ Java provides a software-based platform.
– The Java platform differs from most other platforms in the sense that
it is a software-based platform that runs on the top of other hardware-
based platforms.

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– It has two components:
1) Runtime Environment
2) API(Application Programming Interface)
– Java code can be run on multiple platforms, for example, Windows,
Linux, Sun Solaris, Mac/OS, etc.
– Java code is compiled by the compiler and converted into bytecode.
– This bytecode is a platform-independent code because it can be run
on multiple platforms, i.e., Write Once and Run Anywhere(WORA).

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4.) Secured

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1.3 Features of Java …
4.) Secured
■ Java is best known for its security.
■ With Java, we can develop virus-free systems.
■ Java is secured because:
 No explicit pointer
 Java Programs run inside a virtual machine sandbox
 Classloader: Classloader in Java is a part of the Java Runtime Environment(JRE) which is used to
load Java classes into the Java Virtual Machine dynamically.
 It adds security by separating the package for the classes of the local file system from those that are
imported from network sources.
 Bytecode Verifier: It checks the code fragments for illegal code that can violate access right to
objects.
 Security Manager: It determines what resources a class can access such as reading and writing to
the local disk.
 Java language provides these securities by default.
 Some security can also be provided by an application developer explicitly through SSL(Secure Sockets
Layer) , JAAS (Java Authentication and Authorization Service), Cryptography, etc.

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5.) Robust
■ Robust simply means strong.
■ Java is robust because:
– It uses strong memory management.
– There is a lack of pointers that avoids security problems.
– There is automatic garbage collection in java which runs on the Java
Virtual Machine to get rid of objects which are not being used by a
Java application anymore.
– There are exception handling and the type checking mechanism in
Java.
■ All these points make Java robust.

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6.) Interpreted
– Java byte code is translated on the fly to native machine
instructions and is not stored anywhere.
– The development process is more rapid and analytical
since the linking is an incremental and light weight process.

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7.) Architecture-neutral
– Java is architecture neutral because there are no
implementation dependent features, for example, the size
of primitive types is fixed.
– In C programming, int data type occupies 2 bytes of
memory for 32-bit architecture and 4 bytes of memory for
64-bit architecture.
– However, it occupies 4 bytes of memory for both 32 and 64-
bit architectures in Java.

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8.) Portable
– Java is portable because it facilitates you to carry the Java
bytecode to any platform.
– It doesn't require any implementation.

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9.) High-performance
– Java is faster than other traditional interpreted
programming languages because Java bytecode is "close"
to native code.
– It is still a little bit slower than a compiled language (e.g.,
C++).
– Java is an interpreted language that is why it is slower than
compiled languages, e.g., C, C++, etc.

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10.) Distributed
– Java is distributed because it facilitates users to
create distributed applications in Java.
– RMI (Remote Method Invocation) and EJB are used
for creating distributed applications.
– This feature of Java makes us able to access files by
calling the methods from any machine on the
internet.

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11.) Multi-threaded
– A thread is like a separate program, executing concurrently.
– We can write Java programs that deal with many tasks at once by
defining multiple threads.
– The main advantage of multi-threading is that it doesn't occupy
memory for each thread.
– It shares a common memory area.
– Threads are important for multi-media, Web applications, etc.

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12.) Dynamic
– Java is a dynamic language.
– It supports dynamic loading of classes.
– It means classes are loaded on demand.
■ It also supports functions from its native languages, i.e., C
and C++.
– Java supports dynamic compilation and automatic memory
management (garbage collection).

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1.4. C++ vs Java
Comparison
Index
C++ Java
Platform-
independent
C++ is platform-dependent. Java is platform-independent.
Mainly used
for
C++ is mainly used for system
programming.
Java is mainly used for application programming. It is
widely used in window, web-based, enterprise and mobile
applications.
Design Goal C++ was designed for systems and
applications programming. It was an
extension of C programming language.
Java was designed and created as an interpreter for
printing systems but later extended as a support network
computing. It was designed with a goal of being easy to
use and accessible to a broader audience.
Goto C++ supports the goto statement. Java doesn't support the goto statement.
Multiple
inheritance
C++ supports multiple inheritance. Java doesn't support multiple inheritance through class. It
can be achieved by interfaces in java.
Operator
Overloading
C++ supports operator overloading. Java doesn't support operator overloading.
Pointers C++ supports pointers. You can write
pointer program in C++.
Java supports pointer internally. However, you can't write
the pointer program in java. It means java has restricted
pointer support in java.
Compiler
and
Interpreter
C++ uses compiler only. C++ is compiled
and run using the compiler which
converts source code into machine code
so, C++ is platform dependent.
Java uses compiler and interpreter both. Java source code
is converted into bytecode at compilation time. The
interpreter executes this bytecode at runtime and produces
output. Java is interpreted that is why it is platform
independent.

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1.4. C++ vs Java …
Comparison Index C++ Java
Compiler and
Interpreter
C++ uses compiler only. C++ is compiled
and run using the compiler which converts
source code into machine code so, C++ is
platform dependent.
Java uses compiler and interpreter both. Java source
code is converted into bytecode at compilation time.
The interpreter executes this bytecode at runtime and
produces output. Java is interpreted that is why it is
platform independent.
Call by Value
and Call by
reference
C++ supports both call by value and call by
reference.
Java supports call by value only. There is no call by
reference in java.
Structure and
Union
C++ supports structures and unions. Java doesn't support structures and unions.
Thread
Support
C++ doesn't have built-in support for
threads. It relies on third-party libraries for
thread support.
Java has built-in thread support.
Documentation
comment
C++ doesn't support documentation
comment.
Java supports documentation comment (/** ... */) to
create documentation for java source code.
Virtual
Keyword
C++ supports virtual keyword so that we
can decide whether or not override a
function.
Java has no virtual keyword. We can override all non-
static methods by default. In other words, non-static
methods are virtual by default.
unsigned right
shift >>>
C++ doesn't support >>> operator. Java supports unsigned right shift >>> operator that
fills zero at the top for the negative numbers. For
positive numbers, it works same like >> operator.

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1.4. C++ vs Java …
Comparison Index C++ Java
Inheritance
Tree
C++ creates a new inheritance tree always. Java uses a single inheritance tree always because all
classes are the child of Object class in java. The object
class is the root of the inheritance tree in java.
Hardware C++ is nearer to hardware. Java is not so interactive with hardware.
Object-
oriented
C++ is an object-oriented language.
However, in C language, single root hierarchy
is not possible.
Java is also an object-oriented language. However,
everything (except fundamental types) is an object in
Java. It is a single root hierarchy as everything gets
derived from java.lang.Object.
Note
• Java doesn't support default arguments like C++.
• Java does not support header files like C++.
• Java uses the import keyword to include different classes and
methods.

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1.5. First Java Program | Hello World Example
■ We can write a simple hello java program easily after installing the JDK.
– To create a simple java program, you need to create a class that
contains the main method.
■ Let's understand the requirement first.
■ The requirement for Java Hello World Example
– For executing any java program, you need to
– Install the JDK if you don't have installed it, download the JDK and
install it.
– Set path of the jdk/bin directory.
– Create the java program
– Compile and run the java program

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