I don't know why this is showing error

Question about the task

Crossing the road blindly

Java Syntax, Level 4, Lesson 4

Under discussion

Any suggestions ?

The pedestrian traffic light is programmed as follows:
at the beginning of each hour, the green signal is on for three minutes,
then the signal is yellow for one minute,
and then it is red for one minute.
Then the light is green again for three minutes, etc.
Use the keyboard to enter a real number t that represents the number of minutes that have elapsed since the beginning of the hour.
Determine what color the traffic light is at the specified time.
Display the result as follows:
"green" if the light is green,
"yellow" if the light is yellow, and
"red" if the light is red.

Example for 2.5:
green
Example for 3:
yellow
Example for 4:
red
Example for 5:
green

Requirements:

The program should read a real number from the keyboard.
The program should display text on the screen.
If the light is green, display: "green"
If the light is yellow, display: "yellow"
If the light is red, display: "red"

package com.codegym.task.task04.task0416; /* Crossing the road blindly */ import java.io.*; public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader x = new BufferedReader(new InputStreamReader(System.in)); String s = x.readLine(); double t = Double.parseDouble(s); if((t>=0 && t<3) || t>=5) System.out.println("green"); else if(t>=3 && t < 4) System.out.println("yellow"); else System.out.println("red"); } }

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Sushant

Level 4 , goa, india

14 August 2019, 05:52

try this for yellow and red . else if (t < 4) System.out.println("yellow"); else if (t <= 5) System.out.println("red"); u may solve your program

Ketan Ramteke

Level 7 , Pune, India

5 October 2018, 14:13

You have to use modulus. try This: BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); float num = Float.parseFloat(br.readLine()); float modulo = num%5; String sol = ""; if (modulo<3) sol = "green"; else if(modulo>=3 && modulo<4) sol = "yellow"; else sol = "red"; System.out.println(sol);

Kabeer Rajoria

Level 5 , Gwalior, India

27 October 2018, 16:43

that was really helpful, can you tell me how to basically solve these types of problems i mean mathmatical concept behind it?

Ketan Ramteke

Level 7 , Pune, India

28 October 2018, 08:51

for green 3 min, yellow 1 min and for red 1 min, in total we need 5 min to cycle through whole process. Now let's look into following cases: first three minutes means from 0-3 light is green. i.e for input 0-2.9 we will have signal green and after that from 3- 3.9 (one minute) we will have yellow and after 4-4.9 we will get red signal. Case 1: 2 minutes. 2%5 = 2 (modulo returns reminder and we need it to see which light is on) Case 2: 6 minutes. 6%5 = 1 (lies in 0-2.9) ie green light. Case 2 = 3 minutes 3%5 = 3 (after 3 min green light switches off and yellow light is switched on for next one min) Case 3: 4 min 4%5 = 4 (at min 4 the yellow light switches off and red light switches on for next one min and then green light for the next 3 min and so on)

Ankush Rajput

Level 25 , Bhopal, India

3 October 2018, 12:00

Does the question say that after 5 seconds light will be continuously green all the time ? No. But for all values greater than 5, your program displays green. Lights keep on changing - green for every 3 minutues, then yellow for one minute, then red for one minute and repeat. Think what if someone entered 13 ? What light should be on and how will my program detect it ? You've hardcoded values in your program. If only someone inputs something between 0-5, program will work otherwise not. Think about the logic. Hint - you can make use of modulo(%) arithmetic here.