I can't understand what I'm doing wrong here. The code is outputting correctly with the right range.

Question about the task

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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 reader = new BufferedReader(new InputStreamReader(System.in));
        double minsInHour = Double.parseDouble(reader.readLine());
        //DecimalFormat format = new DecimalFormat("0.#");
        //System.out.println(format.format(minsInHour));
        minsInHour = minsInHour % 5;

        if (minsInHour >= 0 && minsInHour <= 2.9) {
            //System.out.println("This is the green: " + minsInHour + " Mins");
            System.out.println("green");
        }

        if (minsInHour >= 3 && minsInHour <= 3.9) {
            //System.out.println("This is yellow: " + minsInHour + " Mins");
            System.out.println("yellow");
        }

        if (minsInHour >= 4 && minsInHour <= 4.9) {
            //System.out.println("This is red: " + minsInHour + " Mins");
            System.out.println("red");
        }


    }
}

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 reader = new BufferedReader(new InputStreamReader(System.in)); double minsInHour = Double.parseDouble(reader.readLine()); //DecimalFormat format = new DecimalFormat("0.#"); //System.out.println(format.format(minsInHour)); minsInHour = minsInHour % 5; if (minsInHour >= 0 && minsInHour <= 2.9) { //System.out.println("This is the green: " + minsInHour + " Mins"); System.out.println("green"); } if (minsInHour >= 3 && minsInHour <= 3.9) { //System.out.println("This is yellow: " + minsInHour + " Mins"); System.out.println("yellow"); } if (minsInHour >= 4 && minsInHour <= 4.9) { //System.out.println("This is red: " + minsInHour + " Mins"); System.out.println("red"); } } }

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Diego Ortiz

Level 8 , Lima

17 June 2021, 08:20

If you use a double variable the numbers between 2.9 and 3.9 or 4 and 4.9 are infinite. So, you need to take all the points on the line. (10 <= x <= 20 ) == (10 <= x < 15 U 15 <= x <= 20) --->Mathematics

Guadalupe Gagnon

Level 37 , Tampa, United States

4 June 2021, 14:44

I entered 2.95 and it didn't output anything. A bug exists in the code as it should have output "green"

SirJava88

Level 5 , Canadensis, United States

4 June 2021, 14:50

The below code worked. I guess I had to add on .99's. 😐

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 reader = new BufferedReader(new InputStreamReader(System.in));
        double minsInHour = Double.parseDouble(reader.readLine());
        //DecimalFormat format = new DecimalFormat("0.#");
        //System.out.println(format.format(minsInHour));
        minsInHour = minsInHour % 5;
        //System.out.println(minsInHour);

        if (minsInHour >= 0.0 && minsInHour <= 2.99999999) {
            //System.out.println("This is the green: " + minsInHour + " Mins");
            System.out.println("green");
        }

        if (minsInHour >= 3 && minsInHour <= 3.99999999) {
            //System.out.println("This is yellow: " + minsInHour + " Mins");
            System.out.println("yellow");
        }

        if (minsInHour >= 4 && minsInHour <= 4.99999999) {
            //System.out.println("This is red: " + minsInHour + " Mins");
            System.out.println("red");
        }


    }
}

Thomas

Level 41 , Bayreuth, Germany

4 June 2021, 16:20

Even if that validates, the next guy entering 3.999999999 won't get a result as this case isn't handled by your code. That's probably what Guadalupe tried to tell you. But that's easy to fix if you check eg for numbers < 4, then 3.999999999999999999 is still a valid input and handled by your code. If you want to get all numbers from 0 to 0.999999999... you also could cast to an int. then you won't need to check for < 1 but could do a check for == 0 That would open you the usage of a switch-case statement like

System.out.println(switch((int) Double.parseDouble(reader.readLine()) % 5) {
    case 3 -> "yellow";
    case 4 -> "red";
    default -> "green";
});

and that I think looks pretty neat ;) Unfortunately that won't validate as the new switch-case is Java > 12 but you should get the idea (calculating with ints where it may be not obvious on the first view)