Java program to find sum of numbers from 1 to 100

There are multiple way to find sum of numbers from 1 to 100.

for loop :-

  • Start for loop initialize with i = 1.
  • Write testing condition in for loop as i <= 100.
  • Add increment in for loop as i++
  • Initialize a variable sum with 0.
  • Start adding i with the sum at each iteration of for loop.
  • Print sum at the end for loop.

while loop :-

  • Start initialize with j = 1.
  • Initialize a variable add with 0.
  • In while loop condition as j <= 100
  • Start adding j with sum at each iteration of while loop and print j.
  • Add increment statement as j++
  • Print add value at the end of while loop.

IntStream method :-

  • IntStream range(int startValue, int endValue) returns a stream of numbers starting from start value but stops before reaching the end value.
  • Start adding value with the sum in between range.
  • Return type is int and print sum of value.

 

Syntax :     static IntStream range(int startInclusive,   int endExclusive)

mathematical formula method :-

  • In this program, we have used mathematical formula to find the sum of numbers from 1 to 100.

            formula  s = n * (n + 1) / 2;

				
					import java.util.stream.IntStream;

public class FindSum {
	public static void main(String[] args) {

		// from for loop
		int sum = 0;
		for (int i = 1; i <= 100; i++) {
			sum = sum + i;
		}
		System.out.println("from for loop method value :- " + sum);

		// from while loop
		int add = 0;
		int j = 1;
		while (j <= 100) {
			add = add + j;
			j++;
		}
		System.out.println("from while loop method value :- " + add);

		// from IntStream java 8 method
		int sm = IntStream.range(1, 101).sum();
		System.out.println("IntStream sum value :- " + sm);

		// from do while loop
		int k = 1, addition = 0;
		do {
			addition = addition + k;
			k++;
		} while (k <= 100);
		System.out.println("from do while loop value :- " + addition);

		// from mathematical formula method
		int n = 100;
		int s = n * (n + 1) / 2;
		System.out.println("using mathematical (n+1) method :- " + s);
	}
}

Output :-
from for loop method value :- 5050
from while loop method value :- 5050
IntStream sum value :- 5050
from do while loop value :- 5050
using mathematical (n+1) method :- 5050