Top 30 Design Patterns Programs in Java With Examples

Java is a versatile and widely used programming language that can be applied in numerous applications. One common coding exercise that helps Java enthusiasts sharpen their skills is pattern printing. This involves printing various patterns of stars, numbers, and characters on the console.

In this article, we will explore the pattern programs in Java, the importance of and applicability of Java Pattern programs, and therefore we will analyse the 30 different patterns in Java that you can print using Java, including star patterns in Java, how to build number patterns in Java, and characters. But before exploring these pattern programs in Java, take a look at the numerous Java Certification Courses to build your professional portfolio.

What Are Patterns in Java?

Pattern Programs in Java refer to a set of best practices, templates, and reusable solutions that address recurring design or coding problems. Patterns are an essential concept to design and analyse workflows, in the world of programming and software development. These design patterns in Java are essentially recurring, reusable solutions to a specific problem or task.

These patterns offer a structured and proven way to solve common coding challenges, making code more maintainable, efficient, and understandable. They are general guidelines or blueprints that can be applied to different scenarios. Pattern Programs in Java are typically categorised into three main groups:

• Creational Patterns: These pattern programs in Java deal with object creation mechanisms. They abstract the instantiation process, making the system independent of how objects are created, composed, and represented.

• Structural Patterns: Structural pattern programs in Java are concerned with class composition, emphasising the relationships between objects. They help form a structure by defining how objects are connected.

• Behavioural Patterns: Behavioural pattern programs in Java focus on communication between objects and the responsibilities they carry. They assist in defining how objects interact and fulfil their roles in the system.

Patterns can be further described and classified into multiple forms as explained below.

• Design Patterns : These make a combined use of creational, structural and behavioural patterns for building solutions

• Regular expression : They are used for matching and manipulating multiple strings and other data types in Java. One can make use of the java.util.regex package to enable them in your code.

• Coding Patterns : They help in writing an efficient , clean and maintainable code.Illustrations include error handling patterns and coding style patterns.

• Concurrent Patterns: In Java you can make use of patterns like, Reader-Writer, Producer-Consumer and Thread Pool to efficiently coordinate and manage concurrent tasks.

• Architectural Patterns: Java follows different application patterns, such as Model-View-Controller (MVC) or Model-View-ViewModel (MVVM) for structuring and organising user interfaces and application code.

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Importance of Patterns in Java

The importance of pattern programs in Java analyses the realm of mere coding conventions and practices. These patterns are the foundational building blocks that empower developers to craft robust, maintainable, and efficient software solutions. Thus pattern programs in Java serve as time-tested blueprints that offer elegant solutions to recurring problems.

Their significance lies not only in making code more readable and maintainable but also in fostering a culture of best practices, which, in turn, leads to more reliable and scalable applications. The following portrays the importance of Java Pattern Programs:

1. Reusability: Patterns promote reusability by offering reusable code snippets that perform a specific task. Once you have solved a problem using a particular pattern, you can apply that solution to similar situations in the future. This reduces redundancy and leads to more efficient code development.

2. Maintainability: Using patterns makes your code more maintainable. When a specific design pattern is implemented, it is easier for other developers to understand the code structure and functionality, thus simplifying future updates and modifications.

3. Code Quality: Patterns encourage cleaner, more organised, and modular code. Following established patterns helps in writing code that is less error-prone and more reliable, ultimately resulting in better-quality software.

4. Scalability: Patterns are crucial for building scalable systems. When your application follows a pattern, it is easier to add new features or components without disrupting the existing codebase. This scalability is essential for evolving and expanding software projects.

5. Design Consistency: Patterns help maintain design consistency throughout a project. When multiple developers collaborate on a codebase, adhering to well-known patterns ensures a unified approach to problem-solving and code structure.

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Basics of Pattern Printing in Java

The Pattern programs in Java offer a wide range of creative and challenging opportunities to explore. Therefore, Pattern printing is a fantastic way to enhance Java programming skills. Therefore, Before going into specific patterns, let us cover the basic concepts of pattern printing in Java:

The for Loop: The for loop is the most commonly used control structure for pattern printing. It allows you to iterate through a specified range or sequence.

Nested Loops: For complex patterns, you will often use nested loops, where one loop controls the rows and the other controls the columns of the pattern.

Symbols and Characters: Patterns are formed using symbols or characters, such as asterisks (*), numbers, or even alphabet characters.

Now, let us understand the following 30 pattern programs in Java:

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Patterns of Stars

Pattern 1: Printing a Single Star: This is the simplest design pattern in java, consisting of a single asterisk. It is a fundamental pattern to understand the basic concept of printing characters in Java.

*

Pattern 2: Printing a Horizontal Line of Stars: In this design pattern in java, we print a horizontal line of stars. You use a single loop to print a sequence of stars on a single line.

*****

Pattern 3: Printing a Vertical Line of Stars: This pattern focuses on printing a vertical line of stars, which is particularly useful for creating columns of stars.

*

*

*

Pattern 4: Printing a Right Triangle of Stars: In this pattern, you print a right triangle of stars, with each row containing an additional star. Nested loops are typically used to create this pattern.

*

**

***

****

*****

Pattern 5: Printing an Inverted Right Triangle of Stars: This pattern is similar to Pattern 4, but the triangle is inverted. As you move down the rows, the number of stars decreases.

*****

****

***

**

*

Pattern 6: Printing a Hollow Rectangle of Stars: To create design pattern in java, you print a rectangle with a hollow interior. It involves nested loops and conditions to determine when to print spaces or stars.

*****

* *

* *

*****

Pattern 7: Printing a Pyramid of Stars: A pyramid is a common pattern where the number of stars in each row increases while maintaining symmetry. Nested loops are essential for this pattern.

*

***

*****

Pattern 8: Printing a Diamond of Stars: This pattern combines the concepts of a pyramid and an inverted pyramid to create a diamond shape. It requires careful control of spaces and stars.

*

***

*****

***

*

Pattern 9: Printing a Butterfly Pattern: The butterfly pattern is a symmetrical design pattern in java that resembles the wings of a butterfly. It involves both ascending and descending sequences of stars.

* *

** **

*** ***

**** ****

*********

**** ****

*** ***

** **

* *

Pattern 10: Hollow Pyramid of Stars: This pattern involves printing a pyramid of stars, but with the interior left hollow. It is a variation of the regular pyramid pattern and requires conditional statements to manage the spaces and stars.

*

* *

* *

*******

Pattern 11: Hourglass Pattern of Stars: The hourglass pattern is created by printing two pyramids in an inverted manner, resulting in an hourglass shape.

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* *

* *

*

* *

* *

******

Pattern 12: Zigzag Pattern of Stars: In this pattern, stars are printed in a zigzag manner. It is an interesting pattern that requires manipulating the loop structure.

* * *

* * * * *

* * *

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Patterns of Numbers

Pattern 13: Printing a Number Pyramid: In the number pattern program in Java, numbers are printed in the shape of a pyramid. Each row contains numbers in a sequential pattern.

1

121

12321

1234321

Pattern 14: Printing Pascal's Triangle: Pascal's Triangle is a mathematical number pattern program in Java where each number is the sum of the two numbers above it. This pattern is used to create the triangular shape.

1

1 1

1 2 1

1 3 3 1

1 4 6 4 1

Pattern 15: Printing a Fibonacci Triangle: Fibonacci numbers are used in this pattern. Each number is the sum of the two preceding ones. The numbers are arranged in a triangular pattern.

1

1 1

2 3 5

8 13 21 34

Pattern 16: Number Pattern with a Hollow Square: This number design pattern in java, involves printing numbers in a square shape with the interior left empty.

12345

1 2

1 3

1 4

12345

Pattern 17: Number Pattern with a Hollow Rhombus: This pattern prints numbers in the shape of a rhombus with the centre left empty.

1

121

12321

121

1

Pattern 18: Number Pattern with a Hollow Rectangle: Here, numbers are printed in a rectangle shape with the interior left hollow.

12345

1 2

12345

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Patterns of Characters

Pattern 19: Printing the Alphabet in a Pyramid: This pattern involves printing the alphabet in a pyramid shape. Each row includes letters in alphabetical order.

A

A B

A B C

A B C D

A B C D E

Pattern 20: Printing the Diamond of Alphabets: A diamond shape is formed using letters of the alphabet. The letters are printed in a specific order to create this pattern.

A

B B

C C

D D

E E

D D

C C

B B

A

Pattern 21: Printing the Butterfly Pattern with Alphabets: Similar to the butterfly pattern with stars, this pattern involves creating a butterfly shape with letters of the alphabet.

A A

AB BA

ABC CBA

ABCD DCBA

ABCDE EDCBA

ABCD DCBA

ABC CBA

AB BA

A A

Pattern 22: Zigzag Pattern of Characters: Similar to the zigzag pattern of stars, this pattern prints characters in a zigzag manner.

A A

B B

C C

D

E E

F F

G G

Pattern 23: Character Pattern with a Hollow Square: This pattern involves printing characters in a square shape with the interior left empty.

ABCDE

A A

A A

A A

ABCDE

Pattern 24: Character Pattern with a Hollow Circle: In this pattern, characters are printed in a circular shape, with the centre left empty.

ABC

A B

A A

A B

ABC

Pattern 25: Geometric Patterns: This pattern allows you to create various geometric shapes using characters and numbers, combining your creativity and coding skills to design unique patterns.

XOXO

OXOX

XOXO

OXOX

Advanced Patterns

Pattern 26: Printing the Sierpinski Triangle: The Sierpinski Triangle is a fractal pattern that recursively divides a triangle into smaller triangles. It is a challenging and intriguing pattern to create.

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* *

* *

* * * *

* *

* * * *

* * * *

* * * * * * * *

* *

Pattern 27: Printing the Christmas Tree: A Christmas tree pattern is a popular design during the holiday season. It involves printing a tree shape with stars, and additional decorations can be added.

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***

*****

*******

*********

***********

*************

***************

*****************

|||

Custom Patterns

Pattern 28: Print Your Name: Here, you can personalise a pattern by printing your name using characters. This allows you to get creative and showcase your name in an artistic way.

J A V V A

J A A V V A A

J J AAAAA V V AAAAA

J J A V A

Pattern 29: Print a Heart: A heart-shaped pattern is a symbol of love. You can create this pattern using stars or other characters to express your affection.

**** ****

******* *******

***************

*************

*******

***

*

Pattern 30: Print a Smiley Face: Printing a smiley face is a fun and whimsical pattern. You can use various characters to create a happy face on the screen.

******

* *

* o o *

* * *

* --- *

* *

******

Practical Applications of Patterns in Java

Design patterns in java programs in Java are not merely abstract concepts or design principles; they are powerful tools that have tangible and practical applications in the world of Java development. Java Pattern Programs serve as tried-and-true solutions to common programming challenges, offering a structured approach to solving problems efficiently. Therefore, these are the various practical applications of Patterns in Java:

1. Singleton Pattern: The Singleton pattern ensures that a class has only one instance while providing a global point of access. This is particularly useful when you need a single point of control, such as a configuration manager or a connection pool.

2. Factory Method Pattern: The Factory Method pattern in Java is used for creating objects without specifying the exact class of object that will be created. This is handy when you want to decouple the object creation process from the rest of your code.

3. Observer Pattern: The Observer pattern in Java is essential when designing distributed event handling systems that maintain the relationship between objects. It defines a one-to-many relationship between objects, ensuring that when one object changes state, all its dependents are notified and updated.

4. MVC (Model-View-Controller) Pattern: MVC is a widely used architectural pattern for designing graphical user interfaces. It separates the application into three interconnected components: the Model (data and logic), the View (user interface), and the Controller (handles user input).

5. Decorator Pattern: The Decorator pattern in Java allows you to attach additional responsibilities to an object dynamically. It is helpful for adding features to objects without altering their structure.

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Conclusion

Pattern programs in Java are greater tools for writing high-quality, maintainable, and scalable code. They provide proven solutions to common programming challenges and promote code reusability. As a Java developer, understanding and implementing these patterns is not just a best practice; it is a way to elevate your coding skills and deliver efficient, well-structured software solutions.

By exploring how to print star patterns in Java, numbers, and how to print character patterns in Java , you will become more adept at using loops and control structures effectively. Additionally, this creative exercise can boost your problem-solving abilities and accelerate your career as an advanced Java programmer.