Java was developed in the early 1990s to create graphical applications for the web and handheld devices. It became popular for creating interactive web applications called applets. Java is compiled to bytecode that can run on any Java Virtual Machine, making Java programs platform independent. The Java Development Kit includes tools like a compiler and interpreter that are used to develop and run Java programs.

1. 2.Java Evolution
Stand alone pgm->Graphical pgm
 By the end of 1980s and the early 1990s, Object-oriented programming using
C++ took hold.
 C++ was a language that could be used to create a wide range of programs.
 Within few years WWW (World Wide Web) and the Internet would reach critical
mass. This event would cause another revolution in programming.
 We simply Execute the programs on our Machine then it is called as the Stand
Alone Programs, but if we using the Applets for Which includes Graphical
Environment then it is called as Web Applets.
JAVA History
 Every Languages have a history or Every Language has a past Java is developed in 1991
in USA
 And it was called as OAK and it is Developed by James Gosling name of the Engineer
of the Microsoft Sun Team.
 Java Was Developed For Developing the Electronics' things Like VCR , Televisions etc.
The History of Java Includes.
 In 1990 Sun Microsoft Team develop java for Electronics Things but in 1991 java was
Comes with the new name Called as OAK then After that in 1992 java was come with the
new idea of developing Software's for the Handheld Devices Like Mobile Phones ,Pagers
etc.
 But in 1993 Java Was So Popular in the World Wide Web or in the Internet For
Developing Games and Graphical Applications with the help of Applets The Most
Important usable thing in Graphical Programming.
 OAK->Green projects->HotJava->Java

3. 2.2 Features of Java
 Compiled and Interpreter
Java has both Compiled and Interpreter Feature Program of java is First Compiled and
Then it is must to Interpret it .
First of all The Program of java is compiled then after Compilation it creates Bytes
Codes rather than Machine Language ( javac pgm.java) ->prg.class
Then After Bytes Codes are converted into the Machine Language is Converted into
the Machine Language with the help of the Interpreter (java pgrm) (class)
So For Executing the java Program First of all it is necessary to Compile it then it must
be Interpret.
 Platform Independent
Java Language is Platform Independent means program of java is Easily transferable
because after Compilation of java program bytes code will be created then we have to just
transfer the Code of Byte Code to another Computer This is not necessary for computers having
same Operating System in which the code of the java is Created and Executed After Compilation
of the Java Program We easily Convert the Program of the java top the another Computer for
Execution.
 Object-Oriented
We Know that is purely OOP Language that is all the Code of the java Language is
Written into the classes and Objects So For This feature java is Most Popular Language because
it also Supports Code Reusability, Maintainability etc.
 Robust and Secure
The Code of java is Robust and Secure Means ot first checks the reliability of the code
before Execution When We trying to Convert the Higher data type into the Lower Then it
Checks the Demotion of the Code the It Will Warns a User to Not to do this So it is called as
Robust.
 Secure
When We convert the Code from One Machine to Another the First Check the Code
either it is Effected by the Virus or not or it Checks the Safety of the Code if code contains the
Virus then it will never Executed that code on to the Machine.
 Distributed

4. Java is Distributed Language Means because the program of java is compiled onto one
machine can be easily transferred to another machine and Executes them on another machine
because facility of Bytes Codes So java is Specially designed For Internet Users which uses the
Remote Computers For Executing their Programs on local machine after transferring the
Programs from Remote Computers or either from the internet.
 Simple Small and Familiar
Java is a simple Language Because it contains many features of other Languages like c
and C++ and Java Removes Complexity because it doesn't use pointers, Storage Classes and Go
to Statements and java Doesn't support Multiple Inheritance.
 Multithreaded and Interactive
Java uses Multithreaded Techniques For Execution Means Like in other in Structure
Languages Code is Divided into the Small Parts Like These Code of java is divided into the
Smaller parts those are Executed by java in Sequence and Timing Manner this is Called as
Multithreaded In this Program of java is divided into the Small parts those are Executed by
Compiler of java itself Java is Called as Interactive because Code of java Supports Also CUI and
Also GUI Programs.
 Dynamic and Extensible Code
Java has Dynamic and Extensible Code Means With the Help of OOPS java Provides
Inheritance and With the Help of Inheritance we Reuse the Code that is Pre-defined and Also
uses all the built in Functions of java and Classes.

5. 2.3 How Java Differs from C and C++?
1. C Uses header Files but java uses Packages.
2. C Uses Pointers but java doesn't supports pointers.
3. Java doesn't supports storage classes like auto, external etc.
4. The Code of C Language is Converted into the Machine code after Compilation
But in Java Code First Converted into the Bytes Codes then after it is converted into the
Machine Code.
5. C++ supports Operator Overloading but java doesn't Supports Operator
Overloading.
6. In C++ Multiple Inheritance is Possible but in java A Class Can not Inherit the
features from the two classes in other words java doesn't supports Multiple Inheritance
The Concept of Multiple Inheritances is Introduced in the Form of Interfaces.
7. Java Uses import statement for including the contents of screen instead of
#include.
8. Java Doesn't uses goto.
9. Java Doesn't have Destructor like C++ Instead Java Has finalize Method.
10. Java Doesn't have Structure Union , enum data types.

6. Java and Internet
Java is also most popular language on web because java provides us the facility of Applets those
are used for Creating Graphical Applications From Internet a user can download any
application and Execute in the Applet.
Java and World Wide Web
About the time that the details of Java were being worked out, a second, and ultimately, more
important, factor was emerging that would play a crucial role in the future of Java. This second
force was, of course, the World Wide Web. Had the web not taken shape at about the same time
Java was being implemented, with the emergence of the World Wide Web. Java was propelled to
the forefront of computer language design, because the web, too demanded portable programs.
Java Environment
Java Environment includes Classes and Several Methods in the Form Packages or we can also
Called them as the Development Tools The Tools those provides us the Facility to create java
Applications are also Known as the java Development Kit The Development Kit of the java
Includes Several Classes and their methods and properties The Java Development Kit ,name of
the Development tools that is used for creating any applications.
Java Development Kit :
The Java Development Kit (JDK) is a software development environment which
is used to develop java applications and applets

7. JDK :-
Java Development Kit Comes with a collection of tools that are used for developing and
Running java programs.
1) Javac :- Compiler used for Compiling java programs.
2) Java :- For Interpreting java programs.
3) Appletviewer :- For Running Applets.
4) Jdb:- For Connecting java to Database.
JVM:
JVM (Java Virtual Machine) is an abstract machine. It is a specification that
provides runtime environment in which java bytecode can be executed.
Compile : First.java->javac First.java ->First.class
Run : Java First
JVM First.class - run your pgm - machine code.
JRE: Java Run-Time Environment
It has Java Class Library, specific tools, and a stand-alone JVM. It is the most
common environment available on devices to run java programs.

8. how the JDK fits into the Java application development lifecycle.

 Bytecode in Java is an intermediate machine-independent code.
 It is a set of instructions for Java Virtual.
 In general, bytecode is a code that lies between low-level and high-level language
 . The bytecode is not processed by the processor. It is processed by the Java Virtual
Machine (JVM).

11.  Java application programming interface (API)
 Java application programming interface (API) is a list of all classes that are
part of the Java development kit (JDK). It includes all Java packages,
classes, and interfaces, along with their methods, fields, and constructors.