Do-While loop to fill out Array

Question

I am currently working on a project that asked me to set up data entry. In the data entry mode the user will be asked to enter the Scientists data in a loop. if the user responds with 'y' they will be prompted to enter another scientist. The best way I can think to do this is with a do-while loop to fill the array until the user decides its over. I am having trouble with

filling the names into the array, and
the program won't prompt for a name after the initial loop.

Here is what I have:

public class Scientist {  
    private String name; 
    private String field;
    private String greatIdeas;

    public static void main(String[] args) {
        String scientists[] = new String[100];
        int scientistCount = 0;
        Scanner input = new Scanner(System.in);    

        do{
            String answer;
            System.out.println("Enter the name of the Scientist: ");          
            scientists[scientistCount]=input.nextLine();

            System.out.println(scientistCount);
            System.out.println("Would You like to add another Scientist?");
            scientistCount++;
        }

        while(input.next().equalsIgnoreCase("Y"));
        input.close();
    }
}

I am unable to utilize the do-while loop to fill out the array, and after the initial loop the I am no longer prompted to enter the scientists name. @Berger — Chad D
– Chad D, Commented Nov 25, 2016 at 15:14

j.Stark · Accepted Answer · 2016-11-25 15:51:38Z

always prefer to read input using nextLine() and then parse the string.

Using next() will only return what comes before a space. nextLine() automatically moves the scanner down after returning the current line.

A useful tool for parsing data from nextLine() would be str.split("\\s+").

public class Scientist {  
        private String name; 
        private String field;
        private String greatIdeas;

        public static void main(String[] args) {
            String scientists[] = new String[100];
            int scientistCount = 0;
            Scanner input = new Scanner(System.in);    

            do{
                String answer;
                System.out.println("Enter the name of the Scientist: ");          
                scientists[scientistCount]=input.nextLine();

                System.out.println(scientistCount);
                System.out.println("Would You like to add another Scientist?");
                scientistCount++;
            }

            while(input.nextLine().equalsIgnoreCase("Y"));
            input.close();
        }
    }

AleSod · Accepted Answer · 2016-11-25 15:16:47Z

0

Change while(input.next().equalsIgnoreCase("Y")); to while(input.nextLine().equalsIgnoreCase("Y"));

answered Nov 25, 2016 at 15:16

AleSod

4323 silver badges6 bronze badges

Comments

Epig · Accepted Answer · 2016-11-25 15:17:37Z

0

Is this the solution that you mean

String scientists[] = new String[100];
    int scientistCount = 0;
    Scanner input = new Scanner(System.in);    
    boolean again = true;

    while(again){
        System.out.println("Enter the name of the Scientist: "); 
        scientists[scientistCount]=input.nextLine();
        scientistCount++;
        System.out.println(scientistCount);
        System.out.println("Would You like to add another Scientist? y/n");
        if(!input.nextLine().equalsIgnoreCase("y")){
            again = false;
        }
    }
    input.close();

answered Nov 25, 2016 at 15:17

Epig

709 bronze badges

Comments

Alex Karlsson · Accepted Answer · 2016-11-25 15:21:06Z

0

Another way to do it, which i find simpler is with an arraylist, and a regular while loop that breaks after you change a boolean. See following example:

    ArrayList<String> scientists = new ArrayList<String>();
    Scanner input = new Scanner(System.in);
    boolean keepGoing = true;

    while(keepGoing){
        System.out.println("Enter the name of the Scientist: ");
        scientists.add(input.nextLine());
        System.out.println("Would You like to add another Scientist? (y/n)");

        if(input.nextLine().toLowerCase().equals("y")){continue;}
        else{keepGoing = false;}
    }

answered Nov 25, 2016 at 15:21

Alex Karlsson

2961 silver badge11 bronze badges

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