Java quickbook

Explain public static void main(String args[]) in Java.

main() in Java is the entry point for any Java program. It is always written as public static void main(String[] args).

• public: Public is an access modifier, which is used to specify who can access this method. Public means that this Method will be accessible by any Class.
• static: It is a keyword in java which identifies it is class-based. main() is made static in Java so that it can be accessed without creating the instance of a Class. In case, main is not made static then the compiler will throw an error as main() is called by the JVM before any objects are made and only static methods can be directly invoked via the class.
• void: It is the return type of the method. Void defines the method which will not return any value.
• main: It is the name of the method which is searched by JVM as a starting point for an application with a particular signature only. It is the method where the main execution occurs.
• String args[]: It is the parameter passed to the main method.

Singletgon Pattern-

Singleton is a part of Gang of Four design pattern and it is categorized under creational design patterns.Singleton pattern is a design pattern which restricts a class to instantiate its multiple objects. It is nothing but a way of defining a class. Class is defined in such a way that only one instance of the class is created in the complete execution of a program or project.It is used where only a single instance of a class is required to control the action throughout the execution.