Inner class

Core Java/Inner.java

+class Outerclass{
+	int outernum = 10;
+
+	public class Innerclass{
+		//access outerclass attr in inner class
+		//the below print throw an error bcoz only attribute initiale can be done outside a method all other things need to be inside a method
+		//System.out.println("Outer num inside inner class : "+outernum);
+		int innerNUm = 20;
+		public void methodd(){
+			PrivateInnerclass privateobj = new PrivateInnerclass();
+			System.out.println("Secret num in private from another inner class: "+privateobj.secretnum);
+			System.out.println("Outer num inside inner class : "+outernum);
+		}
+	}
+
+	static class StaticInnerclass{
+		//we cannot access non-static context in static context
+		int staticInnernum = 30;
+		void methodd(){
+			System.out.println("Static inner class methodd: "+staticInnernum);
+		}
+	}
+
+	private class PrivateInnerclass{
+		int secretnum = 77;//this is not able to access from outside of Outerclass
+	}
+
+	void methodd(){
+		PrivateInnerclass privateobj = new PrivateInnerclass();
+		System.out.println("Secret num in private : "+privateobj.secretnum);
+		Innerclass innerobj = new Innerclass();
+		System.out.println("Inner num in public from outer class : "+innerobj.innerNUm);
+	}
+}
+
+public class Inner{
+	public static void main(String[] args){
+		//attribute from outer class
+		Outerclass outerObj = new Outerclass();
+		System.out.println("Outer num : "+outerObj.outernum);
+		//attribute from public inner class
+		//create an instance for innerclass using outer class object
+		Outerclass.Innerclass innerpublicobj = outerObj.new Innerclass();
+		System.out.println("Inner num : "+innerpublicobj.innerNUm);
+		innerpublicobj.methodd();// this will call methodd in inner class
+  		//access attribute from static inner class
+  		//to access static inner class dont need to create a instance for outer class
+  		Outerclass.StaticInnerclass innerstaticobj = new Outerclass.StaticInnerclass();
+		System.out.println("Static Inner num from public class : "+innerstaticobj.staticInnernum);
+		innerstaticobj.methodd();
+		//below is throw an error bcoz that is private class.
+		//Outerclass.PrivateInnerclass privateInnerobj = outerObj.new PrivateInnerclass();
+		//access private inner class in outer class but not in outside the class
+		outerObj.methodd();
+	}
+}
+/*
+We can create a instance of a one inner class in another inner class
+Non-static context is not access in static context
+For access static inner class we don't want to create a instance for outer class
+Private inner class accesed by other inner classes (except static) and outer class but not by outside the outer class
+*/
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