Trying to read an input from stdin into an arraylist

Question

I want to be able to input:

Avoid:
alice bob carol dave eve

and have {alice,bob,dave,eve} in the arraylist avoid

package lunch;
import java.util.ArrayList;
import java.util.Scanner;

public class LetsDoLunch {
    public static void main(String[] args){
        String s = "";
        ArrayList<String> avoid = new ArrayList<String>();

        System.out.println("Avoid:");
        Scanner sc2 = new Scanner(System.in);
        while(true){
            s = sc2.next();
            if(s.equals("")){
                break;}
            avoid.add(s);
        }
        System.out.println("done");
        for (int i = 0; i < avoid.size(); i++)
        {
            System.out.println(avoid.get(i));
        }

I'm pretty sure something it's something to do with the sc2.next(); I enter the input line after Avoid: and then nothing happens even after I press enter

Your loop never stops because this condition `s.equals("")` is never `true`. Also, `next()` blocks until new values are available. — Titus, Feb 16 '17 at 05:38
Why not try `Arrays.asList()` to convert the scanner input into an ArrayList much more easily: https://repl.it/Fldv/0 — Sash Sinha, Feb 16 '17 at 05:49

score 1 · Answer 1 · answered Feb 16 '17 at 05:42

1

Instead of s = sc2.next() use s = sc2.nextLine()

answered Feb 16 '17 at 05:42

Ezio

2,837
2
29
45

Still not working. – D. A Feb 16 '17 at 05:44
I just tried and its working. There must be something else in your code that is not working. Debug – Ezio Feb 16 '17 at 05:47
I am agree with Ezio **output** *Avoid: a b c done a b c* – Scary Wombat Feb 16 '17 at 05:53

score 1 · Accepted Answer · answered Feb 16 '17 at 06:09

1

Try this

public static void main(String[] args) {
    String s = "";
    ArrayList<String> avoid = new ArrayList<String>();

    System.out.println("Avoid:");
    Scanner sc2 = new Scanner(System.in);
    Boolean flag = true;
    s = sc2.nextLine();
    String[] words = s.split("\\s+");
    for (int i = 0; i < words.length; i++) {
        avoid.add(words[i]);
    }
    System.out.println("done");
    for (int i = 0; i < avoid.size(); i++) {
        System.out.println(avoid.get(i));
    }

}

answered Feb 16 '17 at 06:09

RAGHU GUNDA

40
5

1

Thanks! This works!!!! – D. A Feb 16 '17 at 06:43
Then Close this question – RAGHU GUNDA Feb 16 '17 at 09:31

Trying to read an input from stdin into an arraylist

2 Answers2