Non static members in Java

Non static members:

• The common functionality of application becomes static.
• Program execution starts with static members (main)
• Static members (variables & methods) need to access using class name.

• The specific functionality must be defined as non static.
• These members need to access using object address.
• Members are :
  1. non static block
  2. non static variable
  3. non static method
  4. constructor

Non static block:

• Set of instructions without identity.
• It is also called instance block
• Executes every time when object creates
• We cannot access instance block (no name)
• JVM access implicitly every time when object creates.

class Test
{
	static
	{
		// static block
	}

	{
		// instance block
	}
}

Non static variable:

• variables store information.
• static variables store common information of all objects.
• static variables data will be shared among the objects.
• static variables get memory only once

• instance variables store specific information of Object
• instance variables data is unique for every object.
• instance variables get memory when object created.

Declaration of variable inside the class and outside to blocks and methods

class Test
{
	static int a ;
	int b ;    // instance variable
	static
	{
		int c ;
	}
}

Constructor:

• It is special java method.
• It must be defined with class name.
• Return type is not allowed.
• Constructors are used to initialize instance variables in Object creation process.

class Test
{
	Test()
	{
		constructor logic...
	}
}

Non static method:

• A block of instructions that performs a task.
• Non static methods represent specific behavior of Object.

class Test
{
	static void common()
	{
		// static functionality
	}
	void specific()
	{
		// non static functionality
	}
}