Java Program to Check Triangular Number

Posted in Java Tutorial

Updated on Oct 30, 2024

By Mari Selvan

👁️ 49 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, various mathematical properties of numbers often pique our interest. One such property is whether a number is a triangular number.

A triangular number or triangle number is the sum of the natural numbers up to a certain value.

In this tutorial, we'll delve into a Java program to check if a given number is a triangular number.

📄 Example

Let's explore the Java code that checks whether a given number is a triangular number.

TriangularNumberChecker.java

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public class TriangularNumberChecker {

// Function to check if a number is a triangular number
static boolean isTriangularNumber(int num) {
  // Formula to check triangular number
  int n = (int) Math.sqrt(2 * num);
  return (n * (n + 1)) / 2 == num;
}

// Driver program
public static void main(String[] args) {
  // Replace this value with your desired number
  int number = 10;

  // Check if the number is a triangular number
  if (isTriangularNumber(number)) {
    System.out.println(number + " is a triangular number.");
  } else {
    System.out.println(number + " is not a triangular number.");
  }
}
}

💻 Testing the Program

To test the program with different numbers, simply replace the value of number in the main method.

Output

10 is a triangular number.

Compile and run the program to check if the given number is a triangular number.

🧠 How the Program Works

The program defines a class TriangularNumberChecker containing a static method isTriangularNumber that checks if a given number is a triangular number using the formula.
Inside the main method, replace the value of number with the desired number to check.
The program then calls the isTriangularNumber method and prints whether the number is a triangular number or not.

📏 Between the Given Range

Let's take a look at the java code that checks and displays triangular numbers in the range of 1 to 50.

TriangularNumbers.java

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public class TriangularNumbers {

// Function to check if a number is triangular
static boolean isTriangular(int num) {
  int sum = 0;
  int n = 1;

  while (sum < num) {
    sum += n;
    ++n;
  }

  return sum == num;
}

// Function to display triangular numbers in the range 1 to 50
static void displayTriangularNumbers() {
  System.out.println("Triangular Numbers in the Range 1 to 50:");

  for (int i = 1; i <= 50; ++i) {
    if (isTriangular(i)) {
      System.out.print(i + " ");
    }
  }

  System.out.println();
}

// Driver program
public static void main(String[] args) {
  // Call the function to display triangular numbers
  displayTriangularNumbers();
}
}

💻 Testing the Program

Output

Triangular Numbers in the Range 1 to 50:
1 3 6 10 15 21 28 36 45

Compile and run the program to see the triangular numbers in the range of 1 to 50.

🧠 How the Program Works

The program defines a class TriangularNumbers containing two static functions: isTriangular and displayTriangularNumbers.
The isTriangular function checks if a given number is triangular using the formula for triangular numbers.
The displayTriangularNumbers function iterates through the range of 1 to 50 and prints triangular numbers.
The main function calls the displayTriangularNumbers function to output the triangular numbers in the specified range.

🧐 Understanding the Concept of Triangular Numbers

Before delving into the code, let's take a moment to understand the concept of triangular numbers.

A triangular number is the sum of the natural numbers up to a certain value, and it can be represented by the formula T_n = n * (n + 1) / 2, where n is a non-negative integer.

For example, T₃ = 1 + 2 + 3 = 6 is a triangular number.