Non Static Inner classes in Java

Non static inner class:

• Defining inner class without static keyword.
• Non static members we access using instance.
• We can access inner class using outer class instance.
• We need to instantiate outer class by which we access non static inner class.

class Outer
{
	void m1()
	{
		System.out.println("Outer class m1()...");
	}
	class Inner
	{
		void m2()
		{
			System.out.println("Inner class m2()...");
		}
	}
}
class Access 
{
	public static void main(String[] args) 
	{
		Outer obj1 = new Outer();
		obj1.m1();

		Outer.Inner obj2 = obj1.new Inner();
		obj2.m2();
	}
}

• We can directly access the functionality by creating object as follows
• Instead of collecting the reference variable, we can access the method directly.
• We need to create object every time to access the functionality

class Outer
{
	static class Inner1
	{
		void fun()
		{
			System.out.println("Inner1 class fun..");
		}
	}
	class Inner2
	{
		void fun()
		{
			System.out.println("Inner2 class fun..");
		}
	}
}
class Access 
{
	public static void main(String[] args) 
	{
		new Outer.Inner1().fun();
		new Outer().new Inner2().fun();
	}
}

We can instantiate the inner class directly as follows:

class Outer
{
	class Inner
	{
		void fun()
		{
			System.out.println("Non static class non static fun..");
		}
	}
}
class Access
{
	public static void main(String args[])
	{
		new Outer().new Inner().fun();
	}
}

• Non static inner class can’t have static functionality.
• We access non static area only with permissions.
• Static members we cannot place inside restricted area.

class Outer
{
	class Inner
	{
		static void fun()
		{
			System.out.println("not allowed...");
		}
	}
}