Preparing for technical interviews is tricky, and if you’re a Java professional, things are more complicated. A popular method of analyzing a Java professional’s expertise is by seeing how well one can make a pattern program in Java. You might have to make a unique Java pattern program, which is not prevalent to nail the interview.
Don’t worry because, in this article, we’ll take a look at multiple Java patterns so you can get a better understanding of the same. The article will also highlight some of the popular design patterns in Java, such as singleton design patterns, and factory design patterns, among others.
All of the patterns we’ve discussed here are made of digits. The best way to practice these patterns would be to try to create the first and if you struggle at some point, compare your code with ours. This way, you’ll understand what does what and would not have any confusion regarding these programs.
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We recommend working your way up from the first pattern. If you have some experience creating a Java pattern program, you can start with any of the designs we’ve shared below:
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What is pattern printing in Java?
Before we delve into the various design patterns in Java, let’s take a look at what exactly pattern printing in Java refers to. To put it simply, pattern printing programs are patterns or symbols that contain alphabets, or characters in a particular form. These programs mainly aim to improve logic, coding skills, and looping concepts. A Java pattern program specifically can be printed in various designs.
Simple Triangle Pattern
Pattern:
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Close the resources
sc.close();
}
}
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Double Triangle Pattern
Pattern:
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6 7
1 2 3 4 5 6
1 2 3 4 5
1 2 3 4
1 2 3
1 2
1
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
//Printing upper half of the pattern
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = rows-1; i >= 1; i–)
{
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
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Triangle Pattern with Repeated Digits
Pattern:
1
2 2
3 3 3
4 4 4 4
5 5 5 5 5
6 6 6 6 6 6
7 7 7 7 7 7 7
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
System.out.print(i+” “);
}
System.out.println();
}
//Close the resources
sc.close();
}
}
Inverted Triangle with Descending Digits
Pattern:
7 6 5 4 3 2 1
7 6 5 4 3 2
7 6 5 4 3
7 6 5 4
7 6 5
7 6
7
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
for (int j = rows; j >= i; j–)
{
System.out.print(j+” “);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
Triangle with Repeating Pattern
Pattern:
1
1 2 1
1 2 3 2 1
1 2 3 4 3 2 1
1 2 3 4 5 4 3 2 1
1 2 3 4 5 6 5 4 3 2 1
1 2 3 4 5 6 7 6 5 4 3 2 1
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
//Printing first half of the row
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
//Printing second half of the row
for (int j = i-1; j >= 1; j–)
{
System.out.print(j+” “);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
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Double Triangle Pattern
Pattern:
1 2 3 4 5 6 7
1 2 3 4 5 6
1 2 3 4 5
1 2 3 4
1 2 3
1 2
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
//Printing upper half of the pattern
for (int i = rows; i >= 1; i–)
{
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = 2; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
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Inverted Double Triangles
Pattern:
1234567
234567
34567
4567
567
67
7
67
567
4567
34567
234567
1234567
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
//Printing upper half of the pattern
for (int i = 1; i <= rows; i++)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++)
{
System.out.print(” “);
}
//Printing i to rows value at the end of each row
for (int j = i; j <= rows; j++)
{
System.out.print(j);
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = rows-1; i >= 1; i–)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++)
{
System.out.print(” “);
}
//Printing i to rows value at the end of each row
for (int j = i; j <= rows; j++)
{
System.out.print(j);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
Double Inverted Triangles
Pattern:
1 2 3 4 5 6 7
2 3 4 5 6 7
3 4 5 6 7
4 5 6 7
5 6 7
6 7
7
6 7
5 6 7
4 5 6 7
3 4 5 6 7
2 3 4 5 6 7
1 2 3 4 5 6 7
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
//Printing upper half of the pattern
for (int i = 1; i <= rows; i++)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++)
{
System.out.print(” “);
}
//Printing i to rows value at the end of each row
for (int j = i; j <= rows; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = rows-1; i >= 1; i–)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++)
{
System.out.print(” “);
}
//Printing i to rows value at the end of each row
for (int j = i; j <= rows; j++)
{
System.out.print(j+” “);
}
System.out.println();
}
//Closing the resources
sc.close();
}
}
Digit Pillar Pattern
Pattern:
1111111
1111122
1111333
1114444
1155555
1666666
7777777
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= rows-i; j++)
{
System.out.print(1);
}
for (int j = 1; j <= i; j++)
{
System.out.print(i);
}
System.out.println();
}
sc.close();
}
}
Binary Digit Pattern
Pattern:
1010101
0101010
1010101
0101010
1010101
0101010
1010101
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
int num;
if(i%2 == 0)
{
num = 0;
for (int j = 1; j <= rows; j++)
{
System.out.print(num);
num = (num == 0)? 1 : 0;
}
}
else
{
num = 1;
for (int j = 1; j <= rows; j++)
{
System.out.print(num);
num = (num == 0)? 1 : 0;
}
}
System.out.println();
}
sc.close();
}
}
Ascending Triangle Pattern
Pattern:
1
2 6
3 7 10
4 8 11 13
5 9 12 14 15
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for (int i = 1; i <= rows; i++)
{
int num = i;
for (int j = 1; j <= i; j++)
{
System.out.print(num+” “);
num = num+rows-j;
}
System.out.println();
}
sc.close();
}
}
Square Java Pattern Program
Pattern:
1 2 3 4 5 6 7
2 3 4 5 6 7 1
3 4 5 6 7 1 2
4 5 6 7 1 2 3
5 6 7 1 2 3 4
6 7 1 2 3 4 5
7 1 2 3 4 5 6
Code:
import java.util.Scanner;
public class MainClass
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println(“How many rows you want in this pattern?”);
int rows = sc.nextInt();
System.out.println(“Here is your pattern….!!!”);
for(int i=1;i< rows+1 ;i++)
{
for(int j=i; j < rows+1 ;j++)
{
System.out.print(j + ” “);
}
for(int k=1; k < i ;k++)
{
System.out.print(k + ” “);
}
System.out.println();
}
sc.close();
}
}
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Star Pattern In Java
Star pattern is considered to be one of the most common design pattern programs in Java, which is mainly used to improve logical thinking, as well as flow control knowledge. In order to display star patterns in Java, two to three loops are generally required, depending on the programs. The first loop of the star pattern in Java is also sometimes referred to as the outer loop, whereas the second loop is the inner one, which contains rows and columns.
Factory Design Pattern In Java
Factory Design pattern in Java is yet another fundamental method used in Java. It is mainly used when there are multiple sub-classes with a superclass, and you need to return one of the sub-classes based on the input. This method successfully eliminates the responsibility of the instantiation of a classroom the client program to the factory class. There are a ton of advantages that you can derive from implementing factory design patterns in Java. Some of them might include, with factory design patterns, codes getting more robust and easy to extend. Furthermore, factory design pattern also allows abstraction between implementation and client classes.
Singleton Design Pattern Java
There are mainly two types of singleton design pattern Java has, namely, early instantiation and lazy instantiation. In this design pattern, a class ensures that only one instance has been created, which can then be used by all the other classes. One of the top advantages of using the Singleton Design Pattern in Java is that you save a lot of memory since only one instance is used every time by all the other classes.
Final Thoughts
We are sure that you’re ready to create a pattern program in Java after going through this list. You can start with any pattern according to your experience and expertise. If you have any questions regarding this topic or this article, please let us know in the comment section below.
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