Java – repeating a method from user-input

Question

I want to write a program that keeps track of how many times a bus is late.

So the user is asked to enter an int value, indicating how many minutes late.

Once a negative int is entered, the program should stop.

What I’m having trouble with is making the program repeat only for inputs of 0 or more.

The program repeats regardless of what int is inputted.

I did something like below:

import java.util.Scanner;

public class LateBus {

    public static void main(String[] args) {
        int enter_minutes = enterMinutes();
        loop(enter_minutes);
    }

    public static int enterMinutes() {
        Scanner enter = new Scanner(System.in);
        System.out.print("How many minutes late was the bus? ");

        int late = enter.nextInt();
        return late;
    }

    public static void loop(int a) {
        while (a >= 0) {
            enterMinutes();
        }
    }

}

Code-Apprentice · Accepted Answer · 2018-10-28 17:12:32Z

Let's look at this function:

public static void loop(int a) {
    while (a >= 0) {
        enterMinutes();
    }
}

The value of a never changes. a >= 0 will always be true or never be true depending on the initial value for a. Since a is used internally to this function, you should not pass it in as a parameter. And you should be sure to change it:

public static void loop() {
    int a = enterMinutes();
    while (a >= 0) {
        a = enterMinutes();
    }
}

Now you call the function like this:

public static void main(String[] args) {
    loop();
}

Note:

Everyone makes logic mistakes in their code as they write it. To find them, you need to learn how to debug. I suggest that you read https://ericlippert.com/2014/03/05/how-to-debug-small-programs/ for some tips on how to debug your code so that you can find these kinds of problems on your own.

forpas · Accepted Answer · 2018-10-28 17:09:01Z

0

The while loop will stop when a is negative, but you do not change its value.
Do it like this

while (a >= 0) {
    a = enterMinutes();
}

now the value changes to what the user inputs.

answered Oct 28, 2018 at 17:09

forpas

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