Core Java
What is Java?
- Java is a high level language(which means user understandable language).
- Initially Java was developed by "James Gosling" at "SunMicro System". Later on SunMicro System is acquired by Oracle Corp.
Software Requirements:
- To write programs, we need an editor. Examples: Notepad, EditPlus, Eclipse etc.
- To execute Java we need JDK. Which contains tools like: Compiler, JRE, JAR, Debuggin Tool etc.
Java Architecture:
File Name: Demo.java
class A{
public static void main(String[] args){
System.out.println("Hello World!!!")
}
}
How to run Java Program in Command Prompt?
- To compile Java Program:
javac fileName.java
- To execute java program:
java className
C:\Users\Khetrabasi PC\Documents\JSpider PRograms\Basics>javac Demo.java
C:\Users\Khetrabasi PC\Documents\JSpider PRograms\Basics>java A
Hello World!!!
NOTE!
- We can create any number of classes in a single program.
- The number of bytecode that will be generated is equal to the number of classes created inside the program.(Considering there are Zero errors.)
- We can create multiple default classes in java file, but we cannot create morethan one pubilc class in a java file.
Java Comments: