CODEWITHSUNDEEP
javaarraysstringint
Big Boss
Big Boss

Reputation: 73

ArrayOutOfBoundsException when trying to access String Array

I am attempting to write a program that outputs the name of a number when you input a number. It works fine for one digit numbers, but I've hit a roadblock. Whenever I input a number greater than 10, it gives me an ArrayOutOfBoundsException. I'm not quite sure why, for I haven't worked with arrays too long. I have only written code to output names for numbers upto 20 till now. Here is the code:

package numericname;

import java.util.Scanner;

public class NumericName {

static String[] Ones = {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten"};
static String[] Mids = {"Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int x;
    System.out.println("Enter a number");
        x = in.nextInt();
    if(x/10 <= 1)
        ones(x);
    if(x/10 > 1 && x/10 < 2)
        mids(x);
}

public static void ones(int x) {
    System.out.println(Ones[x]);
}

public static void mids(int x) {
    x -= 11
    System.out.println(Mids[x]);
    }
}

I added the x - 11 to make the number equal its name in the string array, but it still doesn't work. What am I doing wrong? Thanks!

Upvotes: 0

Views: 66

Answers (6)

Bimde
Bimde

Reputation: 742

Two problems, both relating to you being a victim of Integer Division:

In Java, when you divide two integers, the result is the value of the equation with the decimal truncated. This means that the decimal part is 'cut-off'. For example: 11 / 10 = 1, 19 / 10 = 1, 9 / 10 = 0

Now for the problems:

  1. The first if statement will cause any number less than 20 to evaluate to true (because 19 / 10 == 1).

To fix this: Change it to if (x <= 10)

  1. The second if statement will never be true because x/10 cannot be less than 2 and greater than 1 (because it is an integer!)

To fix this, change it to either:

  • if(x < 20)
  • or, if(x / 10 == 1)

Upvotes: 1

Tejas Jadhav
Tejas Jadhav

Reputation: 93

It's because, x/10 still gives you 1. It's an integer division. You have to change it to floating point.

Just change x/10 and x/20 to x/10.0 and x/20.0 everywhere. Or just cast x to float during division.

Example

if((float)x/10 <= 1)
    ones(x);
if((float)x/10 > 1 && (float)x/10 < 2)
    mids(x);

Upvotes: 0

iammrigank
iammrigank

Reputation: 1

The problem lies in the fact that the division you are attempting is integer division, and this will not work as you expect. Any number from 11 to 19 will yield x/10 as 1 and then the function

ones(x)

Will lead to an ArrayIndexOutOfBounds

Upvotes: 0

William Ku
William Ku

Reputation: 798

my suggested edit for the main() is as follows:

public static void main(String[] args) {
   Scanner in = new Scanner(System.in);
   int x;
   System.out.println("Enter a number");
   x = in.nextInt();
   if(x <= 10) {
      ones(x);
   } else if(x < 20) {
      mids(x);
   }
}

Upvotes: 0

Saurabh Jhunjhunwala
Saurabh Jhunjhunwala

Reputation: 2922

I suppose there are two issues here :

Why are you trying to use multiple arrays, you can club the two. Secondly, why are using x/10, you can simply compare x<10 or x>10 && x<20.

Upvotes: 0

Michael
Michael

Reputation: 539

Your code is checking if (x/10 <= 1), so then the 10s will be true and drop into the ones code in this case. i.e. 11/10 == 1

Upvotes: 0

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