CODEWITHSUNDEEP
javaarraysstringwhile-loop
jforrest1980
jforrest1980

Reputation: 19

NULL Array - how to link it in while loop

Basically I have to prompt a user to enter 10 string values, and then in another loop print them in ascending order, then in a final loop, print them in descending order. My array is bringing back null, obviously because I am not prompting users to enter actual information into the array object. I am really stuck on this. I know I need to somehow reference the "userStrings[]" array in my first while loop. I keep researching and keep getting integer loops questions and For loops. This has to be a while loop. I just can no figure out how to get the userStrings[] to actually fill up when the user enters the values. How do I get it linked in the loop?

public class HomeWork10
{

    public static void main(String[] args)
    {
        String[] userStrings = new String[10];

        int count = 0;
        int count2 = 0;

        while (count < 10)
        {
            System.out.println("Please enter a string value ");

            Scanner input = new Scanner(System.in);
            String userInput = input.next();

            count++;
        }

        while (count2 < 1)
        {
            System.out.println(Arrays.asList(userStrings));
            count2++;
        }      
    }
}

Upvotes: 0

Views: 160

Answers (3)

Suresh Telagareddi
Suresh Telagareddi

Reputation: 39

See below code snippet may solve your problem.

package com.suresh;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class HomeWork10 {

public static void main(String[] args) {
    String[] userStrings = new String[10];
    int count = 0;
    System.out.println("\t Reading Array Elements ");
    while (count < 10) {
        System.out.print("\t Please enter a string value : ");
        Scanner input = new Scanner(System.in);
        userStrings[count] = input.next();
        count++;
    }
    System.out.println("\t PRINTING ORIGINAL ARRAY OF ELEMENTS ");
    count = 0;
    while (count < userStrings.length) {
        System.out.println("\t " + userStrings[count]);
        count++;
    }

    Collections.sort(Arrays.asList(userStrings), new StringAscComparator());
    System.out.println("\t ASCENDING ORDER ");
    count = 0;
    while (count < userStrings.length) {
        System.out.println("\t " + userStrings[count]);
        count++;
    }

    System.out.println("\t DESCENDING ORDER ");
    Collections.sort(Arrays.asList(userStrings), new StringDescComparator());

    count = 0;
    while (count < userStrings.length) {
        System.out.println("\t " + userStrings[count]);
        count++;
    }
}

static class StringAscComparator implements Comparator<String> {

    @Override
    public int compare(String o1, String o2) {
        return o1.compareTo(o2);
    }
}

static class StringDescComparator implements Comparator<String> {

    @Override
    public int compare(String o1, String o2) {
        return o2.compareTo(o1);
    }
}

}

Upvotes: 1

Peavey2787
Peavey2787

Reputation: 138

You created the array with 'String[] userStrings = new String[10];' and inside your while loop to access it you need to do something like this 'userStrings[0] = input.next()' This says the first item in the array userStrings will be set to input.next(). I'm not great at java so I'm not sure what input.next() will do though.

Upvotes: 0

thegauravmahawar
thegauravmahawar

Reputation: 2823

You are not putting the values in the String[]

Do it like this:

 while (count < 10) {
    System.out.println("Please enter a string value ");

    Scanner input = new Scanner(System.in);
    String userInput = input.next();
    userStrings[count] = userInput;
    count++;
}

Also, declare Scanner input = new Scanner(System.in) outside your while() {...}

Upvotes: 1

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