Endless loop while validating user input

Question

I'm trying to validate german postcodes in a input form. But somehow i get stuck in line 15 and my function is just printing "Give me input" in an endless loop.

I expected that sc_plz.nextLine() would be a blocking function but somehow it's not.

import View.AddressView;

import java.io.IOException;
import java.util.Scanner;

public class AddressController {
    AddressView view = new AddressView();

    public Address addAddress()throws IOException{
        //other input questions

        Scanner sc_plz = new Scanner(System.in);
        int code = 0;
        while (!validatePostcode(code))
            view.askPostcode(); //simple System.out.println("Input something")
            String postcode = sc_plz.nextLine();

            try {
                code = Integer.parseInt(postcode);
            }
            catch (NumberFormatException e){
                view.invalidData(); //warning about not got a number
            }
        //other input questions
    }

    private boolean validatePostcode(int plz) throws IOException {
        //legal postcodenumbers are between 01000 -99999
        if (1000 <= plz && plz <= 99999){
            return true;
        }
        else {
            return false;
        }
    }
}

Where is "Give me input" being printed? Is it done by view.askPostcode();? — pathfinderelite
– pathfinderelite, Commented Nov 6, 2016 at 15:20

Matthew Wright · Accepted Answer · 2016-11-06 15:25:01Z

7

Did you forget brackets for your while statement? As it is right now it will always do whatever is in view.askPostcode();. I imagine this is what it should look like:

while (!validatePostcode(code)) {
    view.askPostcode(); //simple System.out.println("Input something")
    String postcode = sc_plz.nextLine();
    try {
        code = Integer.parseInt(postcode);
    } catch (NumberFormatException e){
        view.invalidData(); //warning about not got a number
    }
}

answered Nov 6, 2016 at 15:25

Matthew Wright

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2 Comments

Denny Crane Over a year ago

ugh... yes. staring at it for hours but beeing blind for this. thx!

Hulk Over a year ago

@DennyCrane configuring your editor to auto-indent your code makes such mistakes a lot more obvious.

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