BASICS YOU MUST KNOW - PART 1

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Basics That You Must KNOW


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1: You must know about what is jdk jre jvm

[Note Program Execution Flow]

2: You Must know about installation dir and atleast whats 
in bin folder

3: Why java Platform independent?

4: Why java architecture neutral?

5: Why java is Robust?

- Beacuse of memory management
- Here in Java we dont need to free memory in Heap
- The garabage collector automatically called and clean
- up what ever programmer creates in Heap

6: Why java is portable?

Beacuse java programs are not depend on underlying Hardware 
or operating system 

The abiltity of java programs to run on any platforms
makes java portable.

- No of data types and their size constant on all platforms
  that makes java portable.

- Its not like C C++  their data type size depends on Hardware


7: You must know About Bytecode?

java compiler is responsible for generating bytecode.
Its architecture neutral code
This Bytecode understands by JVM

8: You must know about PATH and CLASSPATH

PATH- It is an operating system environmental path which
is used to locate (javac)java tools.
[java tools present in bin folder]

CLASSPATH- 
Its environmental variable  which is used to locate .class
file

By Default CLASSPATH is '.'  
'.' means current directory


we can change CLASSPATH By Command
-cp or classpath

java -cp

Comments

  1. Unknown7 June 2021 at 13:36

    Q.1 ) You Must Know About What Is JVM, JRE, JDK?
    -->

    JVM --> 1) Java Virtual Machine Is A Abstract Machine.
    2) It Is Also Called As Virtual Machine Because It Doesn't Physically Exist.
    3) JVM Provides Runtime Environment In Which Java Bytecode Can Be Executed.
    4) Also Run Those Program Which are in Other Lang & Compiled TO Java Bytecode
    5) VVM Perform Mainly 3 Task :
    *Loads The Code
    *Verified The Code
    *Execute The Code
    *Provide Runtime Environment


    JRE --> 1) As Called As RTE(Run Time Environment)
    2) Java Run Time Is A Software Which Are Used To Developed Java Applications.
    3) Used For Providing Run Time Environment
    4) It Is Implementation Of JVM
    5) JRE Is Physically Exist
    6) Contains Set Of Libraries + Other Files(That JVM Used At Run Time)


    JDK --> 1) Java Development Kit Is A Software Development Environment Which is Used To
    Developed Java Applications and Applets
    2) JDK Is Physically Exists
    3) Contains JRE + Development Tools Like Javac, Java
    4) JDK Is An Implementation of Any One Of The Below Given Java Platforms :
    *SE(Standered Edition)
    *EE(Enterprise Edition)
    *ME(Micro Edition)

    ReplyDelete
  2. Unknown7 June 2021 at 13:43

    Q. 2) What is In Bin Folder?

    ---> * Bin Folder Holds Binary Files Which Are The Actual Executable Code For Your Program.
    * Each Of These Folder are Sub-Divided Into Debug And Release Folder, Which Simply Correspond To The Project Build Configurations.

    ReplyDelete

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