JavaNotes.txt

Java Programming
- High Level
- Open Source
- Platform Independent
  - WORA - Write Once Run Anywhere
- OOPS - Object Oriented Programming

Types of Programming
- Procedural	- C
- Object Oriented	- C++ / Java
- Functional	- Python / php / Javascript
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Core Java
- Basics - Variables / Data Types
- Loops and If Else / Switch Case
- OOPS & its Principles
- Array / Strings
- File Handling
- Chat Application
  - Networking
  - Multi-threading
  - JDBC - Database
  - Swing - Desktop App Development - GUI (Graphical User Interface)
  - Exception Handling
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Installation of Java
- Download and install JDK

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First Program in Java
- Every program of Java starts with a class
- Class Name should start with capital letter
- Class Name cannot start with a number or any other special character except _ and $
- Class Name must be same as file Name

To compile java program
- javac ClassName.java

To interpret java program
- java ClassName

Why main is public ?
- because JVM search for main method and if main method is public than only JVM can access that
Why main is static ?
- because static variables and methods are loaded with class so main must be loaded with class because main is the entry point of our program...
Why main is void ?
- because main returns nothing in Java...
Why we pass String args[] in main ?
- so that we can pass command line arguments

What is System ?
  - System class is used for 3 purpose
     - Print something on output	- System.out
     - Take Input from user		- System.in
     - Print error on output		- System.err
  - For printing anything java has PrintStream Class
  - For taking input java has InputStream Class
What is out ?
  - out is an instance of PrintStream Class
What is println/print ?
  - println is a method that is defined inside PrintStream class and we access it through out