Java is a programming language.
What is a language?
Language is a mode of
communication, used to share ideas, opinions, and information with one another.
For example, there are two people
John and Joe. To talk with each other or to share their thoughts or ideas or
information they need something that is language. By using language they can
communicate with each other. That language should be understandable by both
John and Joe.
English==== Language ====
Communication Language === Share Information.
Here English is a language.
Which type of language?
It's a communication language.
Why it is used?
Communication Language ==== We
can provide communication between persons to share information or ideas.
Now a person wants to learn
English
----------------------------------------------
Being an English learner person
should follow grammar.
Grammar ==== Collection of rules
and syntaxes.
In the same way, coming to java
Java ==== Language ====
Programming Language ==== Person to Physical device ( computer), to develop
software.
Here java is a language.
Which type of language?
Java is a programming language.
Why programming language is used?
Programming language is used for
communication between persons and computers
The programmer wants to learn
java
-------------------------------------------
Being java learners we should
follow java rules, regulations, and syntaxes
Programming Language ====
Collection of Rules + Syntaxes + Regulations
Now, what is programming?
program is a set of rules to
perform a specific task.
Programming language is used by
the programmer to communicate with the computer.
The computer only knows binary
language means 0's and 1's because internally computer is built on top of a
microprocessor that understands only 0's and 1's, that's why the computer only
understands the binary language/ machine language.
But humans don't understand
binary language so to communicate with humans with computers we need a
translator.
What is a Translator?
A translator is a built-in software
that converts human-readable language to binary language/machine language and
binary language/machine language to human-readable language.
What is Java
- Java is an object-oriented programming language used in distributed environments on the internet.
- High-level programming language
- Easy to read and understand
- Simple and easy to use
Background
Java is the most popular language created in 1991,
publicly released by 1995
Developed by James Gosling at Sun Microsystems
Java was later acquired by Oracle
The motto is “Write once and run anywhere” (WORA).
This means that compiled Java code will run on all java compatible platforms
without the need for recompilation.
The first name is ‘Oak’ because of the Oak tree
outside Gosling’s office. Later changed to Green then to Java Coffee, he loves
the coffee from Indonesia and shortened it to Java in 1995.
Usage
- · Web applications
- ·
Mobile
applications
- ·
Game development
- ·
Embedded systems
- ·
Desktop
applications
- ·
Develop software
- ·
Mobile devices
- ·
Electronic devices
§
Televisions
§
Air conditioners
§
Washing machines
- ·
Online
registration forms
- ·
Banking apps
- ·
Online shopping
apps
Features of java
Editions in Java
There are three editions
in Java. Programmers can learn any of these editions based on the application
they want to make.
- Java Standard Edition -
Contains core libraries, like java. lang, java. util, etc.
- Java Enterprise Edition -
Includes Java APIs,
like JMS, EJB, JSPs/servlets, etc.
- Java Micro Edition -
This edition is used to program Java in cell phones, set-top boxes, handhelds,
and so on.
The most widely used edition
in Java is Java SE (Standard Edition). Java SE encompasses the basics of
Java—most applications require Standard Edition.
How a java program run
- Write a java program
- Save the java program as a .java file
- Compile the .java file with the help of the java compiler
- Once the program is compiled the compiler is going to generate another file called the .class file
- .class file is also known as bytecode file
- This bytecode file can run on any platform either Windows or Linux or macOS.
Java Program Standard
Steps
Real time approach:
Assume that we have a
subject in graduation called Environmental studies. Imagine a university called
JNTUH is going to prepare an ES question paper. Once done with the
question paper they are going to distribute it to the corresponding colleges.
Then the students need to write the exam in a booklet which consists of some
rules and guidelines like it contains only 32 papers no additional will be
provided, use the only blue pen, don't use the red or green pen like this some
guidelines are there.
Once writing the exam is
done the answer sheet should be validated or correction process. Validation is
the process of checking the answer sheet whether the answers are correct or not
and following rules and regulations or not. This process is done by JNTU
Faculty.
Finally, the university
executes the results of all the students. Look at the following approach
Semester Exams
Environmental Studies
===== > JNTUH
1. Write the exam
=====> Students
Booklet
Rules and
Guidelines
2. Validation / Correction
Process =====> JNTU Faculty
2.1. PASS
2.2. FAIL
3. Execute the results
=====> JNTUH
Three standard steps to write a program in java:
In the same way, Java is
a programming language created by Sun Microsystems Later it is handover to Oracle.
JAVA =====> Sun Micro
Systems =====> Oracle
1. Write a program
=====> Programmer
notepad / notepad++ / editplus / editplus++ / IDE's Eclipse or Visual
Studio or Netbeans
Rules,
Regulations and Syntaxes
.java
extension
After completion of a program, we need to save that program by using the .java extension.
Example:
Filename.java
product.java
2. Validation /
Compilation =====> Compiler
2.1. ERRORS
2.2. PASS
Now there are two cases:
If there are errors in
the program .class file is not generated. If there are no errors in the program
.class file will be generated.
Case 1: There is no
errors =====> .class file (Binary/Machine/0's and 1's) is
generated
Case 2: Errors =====>
.class file is not generated
After the completion of
java program by using compiler we will compile the program.
A compiler is a software
that converts the source code to a class file that is the binary language of 0s
and 1s.
3. Execute the program
=====> JVM ( Java Virtual Machine )
.class file
is generated
JVM executes the .class
file and generates the output.
Anatomy of java
JDK: Java development kit, it is a super set of JRE and is a software development environment used to develop java applications and applets.
Once the JDK has been installed it will provide a lot
of other components like JRE (Java Runtime Environment), JVM (Java Virtual
Machine), class libraries, and other libraries.
Write and compile the program by using the compiler
provided by JDK.
Once the program is compiled .class file will be
generated.
JRE: Run the .class file using JRE
JRE will run and execute the .class file with the help
of three components such as JVM, class libraries, and other libraries.
JVM: JVM is a virtual environment inside which the
programs will run. It is platform-independent, it loads the java code,
validates the code, and executes the code.
To run the program how does it achieve this
environment?
For achieving this virtual machine environment, it
would need some runtime libraries, that are provided by this class libraries.
Installing Java
Open the browser and type JDK java download
Click on oracle.com
Select the appropriate OS and download
Install JDK
To check whether JDK is successfully installed or not:
Open cmd
Type java -version
Installing Eclipse
Open browser and type eclipse download
Click on eclipse.org
Click on get eclipse IDE and download it
True or False Questions
1. Compiler is always going to compile or execute .java files
True
2. Compiler always generates .class files
False
Because if a program has errors it will not generate a .class file
3. Compiler is always going to generate the .class files if and only if it will follow all the java rules regulations and syntaxes.
True
4. JVM always executes either .java or .class files
False
5. Compiler always executes .class files
False
check your knowledge
I hope you have learned something new today!
Now it's time to check your knowledge!!
Let's answer the below queries
Write answers to the following questions in the comments section
- What is java?
- What is JDK?
- What are the applications/uses of java?
- What is a language?
- What is a translator?
- What is a program?
- Who invented java and in which year?
- What are the features of java?
- Why java is named like that?
- How many standards are there in java and what are those?
- How many standard steps in java and explain it in your words?
- What is JVM, JRE and explain in brief?
- Installation steps of Java and Eclipse?
- What is .class file and when it will generate(include cases)?
- What is the extension of java file?
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