This document discusses the decorator design pattern in Java. It explains that the decorator pattern allows dynamically adding or overriding behaviors of individual objects at runtime without affecting other objects. It provides examples from the Java standard library like BufferedReader which decorates Reader. The document also includes code to demonstrate how the decorator pattern works with currency objects.

1. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
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2. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 I was thinking about writing about the
decorator design pattern in Java when I first
wrote 10 interview questions in the Singleton
Pattern in Java.
 As the design pattern It is very important in
the creation of software and is equally
important in any main Java interview,

3. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 it is always good to have a clear understanding of
several design standards in Java. In this article,
 we will explore and learn the standard Decorator
Design in Java, which is a prominent design
pattern in Java and you can see much of its
example in the JDK itself.
 JDK uses the decorator standard in the IO
package, where it decorated the Reader and
Writer classes for various scenarios, for example,

4. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 BufferedReader and BufferedWriter are examples of
decorator design patterns in Java. From the
perspective of the project,
 it is also a good idea to learn how existing things work
in the JDK itself, for example. As HashMap works in
Java or how the SubString method works in Java,
 this will give you an idea of the things you need to take
into account when designing your class or interface in
Java.
 Now let's go to the Decorator standard in Java.

5. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 The decorator design pattern is used to improve the
functionality of a specific object at runtime or
dynamically ·
 At the same time, other instances of the same class
are not affected by this individual object to obtain
 The design pattern of the decorator is based on
abstract classes and we derive the concrete
implementation of these classes.
 It is a structural design pattern and more used. is
resolved by the Decorator standard: Now the question
is why this pattern came into existence,

6. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 what is the problem with the existing system, then, the
answer is: if someone wants to add some functionality
to an individual object or change the status of a certain
object at runtime,
 what is possible is not possible. We can provide the
specific behavior to the entire object of this class at
design time by inheritance help or by using the
subclass,
 but the Decorator pattern makes it possible for us to
provide individual object of the same class with a
specific behavior or state at runtime.

7. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 This does not affect another the object of the
same class in Java. When using the Decorator
pattern in Java ·
 When the subclass is impractical and we need a
large number of different possibilities to create an
independent object or we can say that we have a
number of combinations for an object.
 When we want to add functionality to the
individual object and not to every object at
runtime, we use the design pattern of the
decorator.

8. STANDARD DECORATOR DESIGN IN
JAVA WITH JAVA EXAMPLE
 Explanation of the code: We can understand this
in the following term: Interface 1.Component: In
our example,
 the currency interface is a component that is used
alone or we need a decorator for that.Component
2.Concrete: implement Compo nent and add new
behavior to this object dynamically.
 Dollar and Rupee are the concrete application of
the coin.3.Decorator: Decorator contains a
relation in a simple word,

9. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 we can say that it has an instance variable
that contains reference for the component that
implement the same component that they are
going to decorate.
 Here a decorator is an abstract class that
extends the currency.4.Decoration of
concrete: it is an implementation of the
Decorator.

10. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 Then, dollar dollar and dg dollar are the
implementation of the decorator contains
instance variable for the interface of the
component or the thing they are going to
decorate.
 Vantage of the design pattern Decorator in
Java In summary,

11. STANDARD DECORATOR
DESIGN IN JAVA WITH JAVA
EXAMPLE
 To get the decorator master's domain, I
suggest looking inside the JDK library itself
and discover what classes are decorated,
because they are decorated.
 Think also about the scenario where
inheritance is impractical and you have more
flexibility and try to use the decorator pattern
in Java.