Structural pattern

Author: Anshika15

README.md

@@ -37,3 +37,48 @@
                     Disadvantages:- - Complexity is high
                                     - Tends to rely on other patterns.
                                     - Low popularity.
+
+### 2. Structural Patterns:- 
+      It provides a common solution to common issues realted to object structures and features of those factors is that they rely on concepts of inheritance, polymorphism
+      
+      Types of Structural Patterns:-
+      
+      i) Adapter Pattern:- This pattern is generally used when there is a need to combine the capabilities of the interface.
+            use cases:- - In case of legacy applications.
+                        - In case of converting an interface into another.
+                        - in case of translating a client's requests for a website.
+
+            examples of usage in Java API:-
+                        - Arrays.asList();
+                        - I/O streams
+                     
+      ii) Bridge pattern:- It aims to separate a large structure of classes into two heirarchy.
+            use cases:- - when having a complex structure of classes with similar implementations.
+                        - when want to impose the same implementation for multiple objects.
+                        - when providing a map b/w orthogonal class hierarchies.
+
+      iii) Filter pattern:- It enables us to define filters for our objects.
+      
+      iv) Composite pattern:- 
+             features:- - Designed on tree structure.
+                        - Root level is the Component.
+                        - Leaf objects implement the Component.
+                        - Composite perform the same operations as the leafs.
+                        - Composite knows about the child objects.
+                        
+       v) Decorator pattern:-
+             features:- - Decorates a base object with multiple features.
+                        - Adheres to the single responsibility principle.
+                        - uses OOP principles.
+                        
+       vi) Facade pattern:- The pattern is used for providing an interface to the client while hiding all the complexities of a system.
+       
+       vii) Flyweight pattern:- It is used for memory optimization purposes. The design pattern is usually chosen whenever there is a need to reduce the number of created objects.
+                              - It has capability to optimize object structure.
+                           
+       viii) Proxy pattern:- It is basically a class that serves as an interface between a client application and another object.
+                  usage:- - when creating a wrapper to cover main's object complexity.
+                          - when creating a security layer for preventing unauthorized access.
+                  weakness:- - It can  have a single proxy.
+                             - creates complexity.
+