Triangular Number in Java ISC 2007

A class Numbers contains the following data members and methods to check for triangular numbers.

A triangular number is formed by the addition of a consecutive sequence of integers starting from 1.

Example:
1 + 2 = 3
1 + 2 + 3 = 6
1 + 2 + 3 + 4 = 10
1 + 2 + 3 + 4 + 5 + 15
Therefore, 3, 6, 10, 15 are triangular numbers.

Class name: Numbers
Data members/instance variables:
n: integer to be checked whether it is triangular or not.
Member function/methods:
void getNum(): to accept the integer n.
int check(int): to check if n is triangular.
void display(): to display a suitable message whether n is triangular or not.

Specify the class Numbers giving details of the methods getNum(), check(int) and display(). The main() function need not be written.

import java.io.*;
class Numbers{
    private int n;
    public void getNum()throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("N = ");
        n = Math.abs(Integer.parseInt(br.readLine()));
    }
    public int check(int num){
        int sum = 0;
        int i = 1;
        if(num < 3)
            return 0;
        while(sum < num){
            sum += i;
            i++;
        }
        if(sum == num)
            return 1;
        return 0;
    }
    public void display(){
        if(check(n) == 1)
            System.out.println(n + " is triangular.");
        else
            System.out.println(n + " is not triangular.");
    }
}

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