Why does an error occur? If you cant see the triangle with the sides you need to display: "The triangle is not possible." 
package com.codegym.task.task04.task0415;

import java.io.*;

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String sNumber1 = bufferedReader.readLine();
        String sNumber2 = bufferedReader.readLine();
        String sNumber3 = bufferedReader.readLine();
        int a = Integer.parseInt(sNumber1);
        int b = Integer.parseInt(sNumber1);
        int c = Integer.parseInt(sNumber1);
        if  ((a + b) <= c || (a + c) <= b || (b + c) <= a) {
            System.out.println("The triangle is not possible.");
        }
        else{
            System.out.println("The triangle is possible.");
        }
    }
}