How to Check If a Triangle Can be Formed in Java

The sides of a triangle is constrained by the rule that the sum of any of its two sides is always bigger than the third side. Using this rule, we can find whether 3 sides given for a triangle is valid or not. The following sample Java program checks whether the given 3 sides can form a valid triangle.

import java.util.Scanner;

 * Validates whether the given 3 sides can form a triangle or not.
 * @author jj
public class ValidTriangle {
    public static void main(String[] args) {
        Scanner sn = new Scanner(;
        System.out.println("Enter length of first side of triangle:");
        double a = sn.nextDouble();
        System.out.println("Enter length of second side of triangle:");
        double b = sn.nextDouble();
        System.out.println("Enter length of third side of triangle:");
        double c = sn.nextDouble();
        ValidTriangle vt   = new ValidTriangle();
        if(vt.isTriangleValid(a, b, c)) {
            System.out.println("Sides entered can form a triangle!");
        }else {
            System.out.println("Sides entered cannot form a triangle!");

     * Checks whether the 3 sides can form a triangle
     * The sum of any two sides must be greater than the other side
     * @param a
     * @param b
     * @param c
     * @return 
    private boolean isTriangleValid(double a, double b, double c) {
        if((a+b)>c && (a+c)>b && (b+c)>a) {
            return true;
        }else {
            return false;

Do you have a programming problem that you are unable to solve? Please send us your problem and we will publish the solution on this site within 48 hours! Please email us.

Leave a Reply