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Question about the task

Crossing the road blindly

Java Syntax, Level 4, Lesson 4

Resolved

I've tried everything to solve it, but it seems that i'm missing something. Please, help me!

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 { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); double t = Double.parseDouble(br.readLine()); if (t > 5) t = t % 5; if (t < 3) System.out.println("green"); else if (t < 4) System.out.println("yellow"); else if (t <= 5) System.out.println("red"); } }

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Igor Alves

Level 6 , Aveiro, Portugal

30 April 2019, 10:59

Thx everyone :)

Sarom Thin

Level 15 , Fresno, United States

30 April 2019, 05:23

useful

One thing to note is that we start the clock from 0. So that means: 0.0-2.9 minutes will be green. 3.0-3.9 minutes will be yellow. 4.0-4.9 minutes will be red. And so it will actually loop again at 5 minutes. Because 5.0 % 5.0 = 0.0. So you just need to correct the last if/else statement. As for your first if statement. Just like Greggics said it is unnecessary. You do need (t % 5). That is important, but you don't need an if statement that controls that expression. To see why go ahead and take any number less than 5(that is not a negative number) and mod it by 5. What will the outcome be?

Greggics

Level 20 , Frankfurt am Main, Germany

29 April 2019, 16:10

solution

I think there is a problem with the last else-if statement. Whenever you enter the value 5, your program should display "green". But you display red instead:

else if (t <= 5)
            System.out.println("red");

which is wrong. You need to adjust the last else-if statement. :) Also: The first if-statement doesn't really do anything for you, does it? Setting t to modulo 5 without the proceeding if-clause should fix the problem as well.