Do-while loop issue

Question

public class Valtiotesti 
{
    public static void main(String[] args) 
    {
        Scanner lukija = new Scanner(System.in);
        String nimi, pääkaupunki;
        int asukasluku;

        ArrayList<Valtio> valtiot = new ArrayList<Valtio>();     

        do{
            System.out.println("Anna valtion nimi: ");
            nimi = lukija.nextLine();

            if(nimi.length()>0){
                System.out.println("Anna ko. valtion pääkaupunki: ");
                pääkaupunki = lukija.nextLine();
                System.out.println("Anna ko. valtion asukasluku: ");
                asukasluku = lukija.nextInt();
                Valtio valtio = new Valtio(nimi, pääkaupunki, asukasluku);
                valtiot.add(valtio);
            }
        }
        while(nimi.length()>0);
    }
}

I have this problem with my code: I want to read countries into ArrayList containing country's name (nimi), capital (pääkaupunki), and population (asukasluku), until the user enters empty string as name of the country (just presses enter).

However when the code enters next round, netbeans just prints out the question: "Anna valtion nimi: " (give country's name), and finishes the program (BUILD SUCCESSFUL), WITHOUT giving the chance to enter new Country...

Eran · Accepted Answer · 2014-11-18 13:25:33Z

4

You must add a nextLine after your nextInt to consume the rest of the line that contained that int :

    if(nimi.length()>0){
        System.out.println("Anna ko. valtion pääkaupunki: ");
        pääkaupunki = lukija.nextLine();
        System.out.println("Anna ko. valtion asukasluku: ");
        asukasluku = lukija.nextInt();
        Valtio valtio = new Valtio(nimi, pääkaupunki, asukasluku);
        valtiot.add(valtio);
        lukija.nextLine();
    }

answered Nov 18, 2014 at 13:25

Eran

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1 Comment

Eran Over a year ago

@dovy lukija.nextInt() reads part of a line (the newline is not read). Therefore, in the next iteration of the loop, nimi = lukija.nextLine(); gets that new line instead of getting the next line, so nimi.length is 0 (the new line characters are truncated) and the loop is exited.

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