Java - How to quit a While Loop mid loop

Question

I'm trying to make a program that asks an electrician to enter a number in Volts. If he/she enters a value either bigger than 20 or less than 0, the program should end without prompting the user to go again. Right now, I have it so it prompts the user to quit or continue, which I don't want. Here's the guts of the program:

public static void main(String[] args) {

    Scanner kbReader = new Scanner(System.in);
    String input = "";
    int voltage;
    boolean Loop = true;

    while (Loop) {

        System.out.print("Enter a numeric value of 0 to 20 volts");
        input = kbReader.nextLine();
        voltage = Integer.parseInt(input);

        if (voltage < 0 || voltage > 20) {
            System.out.println("Invalid input.");
        }

        else if (voltage >= 0 && voltage < 5) {
            System.out.println("Insufficient Voltage - Replace Relay"); 
        }

        else if (voltage >= 5 && voltage < 15) {
            System.out.println("Low Voltage"); 
        }

        else if (voltage >= 15 && voltage < 18) {
            System.out.println("Voltage is in proper range");
        }
        else if (voltage >= 18 && voltage <= 20) {
            System.out.println("Voltage is high - Check Transformer"); 
        }

        System.out.print("\n\nType \"Q\" to quit, or type nothing to go again.");
        input = kbReader.nextLine();

        if (input.equalsIgnoreCase("q")) {
            Loop = false;
        }
    }
}

The indentation seems to be a bit off. I'm not too sure how to fix that.

You've got two input = kbReader.nextLine() in your loop. That doesn't make sense!!! You should probably take the first one outside (before the beginning of) the loop. Alternatively, you can place the exit-condition immediately after the first input-scan, and get rid of the second input-scan. — barak manos
– barak manos, Commented Nov 20, 2014 at 18:38
Looks like you should replace 'System.out.println("invalid input");' with 'break;' — newcoder
– newcoder, Commented Nov 20, 2014 at 18:41
@AndyFedoroff only quotes should be in quotes, reverting your changes — Matsemann
– Matsemann, Commented Oct 15, 2016 at 8:31

StackFlowed · Accepted Answer · 2014-11-20 18:41:09Z

1

All you need to do is

if (voltage < 0 || voltage > 20) {
    System.out.println("Invalid input.");
    break;
}

answered Nov 20, 2014 at 18:41

StackFlowed

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Comments

Sarthak Mittal · Accepted Answer · 2014-11-20 18:41:47Z

0

You can use a break in that first if clause :

if (voltage < 0 || voltage > 20)
{
  break;
}

answered Nov 20, 2014 at 18:41

Sarthak Mittal

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Comments

Noah Kettler · Accepted Answer · 2014-11-20 18:42:47Z

0

You can try using a break;. Breaks allows the while loop to exit.

answered Nov 20, 2014 at 18:42

Noah Kettler

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