Pyramid Program in Java

Pyramid Program in Java | There are many pattern programs are written by programmers for practice purposes. The pyramid star pattern in Java is one of them. In this post, we will display half pyramid star pattern, inverted half pyramid star pattern, full pyramid star pattern, full pyramid star pattern at the center of the screen, and inverted full pyramid star pattern.

Half Pyramid Star Pattern

1. Write a Java program to display the half pyramid star pattern.

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

The Java program for the above half pyramid star pattern is,

public class Pyramid {
   public static void main(String[] args) {
      // outer loop for row
      for (int i=1; i <= 5; i++) {
         // inner loop for column
         for(int j=1; j <= i; j++) {
            // print star
            System.out.print("* ");
         }
         // new line
         System.out.println();
      }
   }
}

The previous program uses the increment operator to display the Half pyramid star pattern in Java. But we can also use the decrement operator.

Half pyramid star pattern using both increment and decrement operators,

Here we will use decrement operator for outer loop and increment operator for the inner loop to print above print.

for (int i=5; i >= 1; i--) {
   for(int j=i; j <= 5; j++) {
      // print star
      System.out.print("* ");
   }
   // new line
   System.out.println();
}

Now, we will use the increment operator for the outer loop and decrement operator for the inner loop to print the same (above) pattern.

for (int i=1; i <= 5; i++) {
   for(int j=i; j >= 1; j--) {
      // print star
      System.out.print("* ");
   }
   // new line
   System.out.println();
}

Inverted Half Pyramid Star Pattern

2. Write a Java program to display the inverted half pyramid pattern of star.

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

The code for the inverted half pyramid star pattern is,

public class InvertedPyramid {
   public static void main(String[] args) {
      for (int i=5; i >= 1; i--) {
         for(int j=i; j >= 1; j--) {
            // print star
            System.out.print("* ");
         }
         // new line
         System.out.println();
      }
   }
}

3. Display the below triangle of star pattern in Java.

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

The code for the above pattern is given below,

import java.util.Scanner;
public class Pyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {
         // space
         for(int j=1; j <= n-i; j++)
         System.out.print(" ");

         // star
         for(int k=1; k <= i; k++)
         System.out.print("*");

         // new line
         System.out.println();
      }
   }
}

4. Write a C program to display the below triangle of star pattern.

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

The Java code for the above star pattern,

import java.util.Scanner;
public class Pyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {
         for(int j=1; j <= n; j++)
         if(j < i)
         System.out.print(" "); // space
         else
         System.out.print("*"); // star
         // new line
         System.out.println();
      }
   }
}

Full Pyramid Star Pattern in Java

5. Write a program to display the full pyramid star pattern.

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

Full pyramid star pattern program in Java can be written as,

import java.util.Scanner;
public class FullPyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {
         // space
         for(int j=1; j <= n-i; j++)
         System.out.print(" ");

         // star
         for(int k=1; k <= (2*i-1); k++)
         System.out.print("*");

         // new line
         System.out.println();
      }
   }
}

There are many other ways to display the same pattern,

// loop
for (int i=1; i <= n; i++) {
   for(int j=1; j <= 2*n; j++)
   if(j <= n-i)
   System.out.print(" "); // space
   else if(j < n+i)
   System.out.print("*"); // star

   // new line
   System.out.println();
}

The same pattern also can be displayed using the recursion technique,

import java.util.Scanner;
public class FullPyramid {

   // static variable
   static int stars = -1;

   // main method
   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      displayFullPyramid(n);
   }
   private static void displayFullPyramid(int n) {
      if(n <= 0) return;

      // variables
      int space = n-1;
      stars += 2;

       // space
      for(int i = 0; i < space; i++)
      System.out.print(" ");

      // stars
      for(int j = 0; j < stars; j++)
      System.out.print("*");

      // new line
      System.out.println();

      // recursive call
      displayFullPyramid(--n);
   }
}

6. Full pyramid star pattern at the center of the screen in Java,

Generally, on a computer screen, we can print Maximum 80 characters horizontally. Here we will print the full pyramid for n lines.

import java.util.Scanner;
public class Pyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0, c=80;      

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {

         for(int j=1; j <= (c/2-i); j++)
         System.out.print(" "); // space
         
         for(int k=1; k <= (2*i-1); k++)
         System.out.print("*"); // star
	 
         // new line
         System.out.println();
      }
   }
}

Inverted Full Pyramid Star Pattern

7. Write a program to display inverted full pyramid star pattern

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

Solution1:- Using only increment operators,

import java.util.Scanner;
public class InvertedPyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {

         for(int j=1; j < 2*n; j++)
         if(j < i)
         System.out.print(" "); // spaces
         else if(j <= 2*n-i)
         System.out.print("*"); // stars
	 
         // new line
         System.out.println();
      }
   }
}

Solution2:- Using both increment and decrement operators,

for (int i=n; i >= 1; i--) {
  for(int j=1; j <= n-i; j++)
  System.out.print(" "); // spaces
  for(int k=1; k <= 2*i-1; k++)
  System.out.print("*"); // stars
  // new line
  System.out.println();
}

Solution3:-

for (int i=n; i >= 1; i--) {
   for(int j=n; j > i; j--)
   System.out.print(" "); // spaces
   for(int k=1; k <= 2*i-1; k++)
   System.out.print("*"); // stars
   // new line
   System.out.println();
}

8. Write a Java program to display the below triangle star pattern

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

Code for the above pattern is,

import java.util.Scanner;
public class Pyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {

         for(int j=1; j <= n-i; j++)
         System.out.print(" "); // spaces
         for(int k=1; k <= i; k++)
         System.out.print("* "); // stars
	 
         // new line
         System.out.println();
      }
   }
}

9. Write a Java program to display the below triangle star pattern

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

The code for the above pattern is,

import java.util.Scanner;
public class Pyramid {

   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = 0;

      // take input
      System.out.print("Enter number of rows:: ");
      n = scan.nextInt();

      // loop
      for (int i=1; i <= n; i++) {

         for(int j=1; j <= 2*n; j++)
         if(j <= i || j > (2*n-i))
         System.out.print("*"); // star
         else
         System.out.print(" "); // space
	 
         // new line
         System.out.println();
      }
   }
}

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