Java program to check if number is a Triangle Number.

import java.util.Scanner;

// © 2017 TheFlyingKeyboard and released under MIT License

public class IsNumberSquare {
  public static void main(String[] args) {
    Scanner input = new Scanner(;
      int n;
      System.out.print("Enter number: ");
      n = input.nextInt();
      if(isSquare(8 * n + 1)){
      	System.out.print("Number is triangle number");
      	System.out.print("Number is not triangle number");
  static Boolean isSquare(int n)
        for (int i = 0; i < n / 2 + 2; i++)
            if (i * i == n)
                return true;

        return false;


Java Check If Number Is Triangle Number
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