Return java array with no values inside

Question

I have a program below where an array contains some int values. It returns the array in a sequence depending whether the int value is a multiple of 10. This program does that fine, but how would I check to see if the array has no int values inside it? I get an error (Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0) Thankyou!

public class Test1{
   public static void main(String[] args){
      int[] nums = {};
      int[] array = tenRun(nums);
      int i;
      for(i = 0; i < array.length - 1; i++) 
         System.out.print(array[i] + ", ");
      System.out.println(array[i]);
   }

   public static int[] tenRun(int[] nums) {
      int current;
      int i = 0;

      while(i < nums.length && nums[i] % 10 != 0)
         i++;   
      if(i >= nums.length)
         return nums;

      current = nums[i]; 
      i++;

      while(i < nums.length) {
         if(nums[i] % 10 == 0)
            current = nums[i];
         else
            nums[i] = current;
         i++;
      }                                                      
      return nums; 
   }
}

Meepo · Accepted Answer · 2017-10-16 05:13:03Z

1

First of all, it's not good style to declare an array with {}.

If anybody could call tenRun(int[] nums), then I'd probably check to see if it is empty or null like this:

if(nums == null || nums.length == 0)

but since you only want your code to run when it's not null and when it's not empty, do it like this:

if(nums != null && nums.length > 0) {
    //code here
}

Your for loop in main should look like:

//get rid of int i;
if(array.length > 0) {
    System.out.println("{");
    for(int i = 0; i < array.length - 1; i++) {
        System.out.print(array[i] + ", ");
    }
    System.out.println("}" + array[i]);
} else {
    System.out.println("{}");
}

edited Oct 16, 2017 at 5:13

answered Oct 16, 2017 at 4:40

Meepo

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5 Comments

Sombra Devon Over a year ago

I still can't get my head around it, I think I might be over complicating it for myself. If I have an array of {8, 40, 7, 9, 30, 6, 4, 40, 1, 9} it returns 8, 40, 40, 40, 30, 30, 30, 40, 40, 40 as expected but if someone leaves the array blank {} it still throws the exception.

Meepo Over a year ago

@SombraDevon I figured it out. You have a fencepost problem on your hands. You reach the end of the loop where i = array.length -1, but then you try to print out array[array.length] because the for loop still tries to increment i.

Sombra Devon Over a year ago

Thanks! That fixes it! However, would it be possible to check for that in the tenRun method?

Meepo Over a year ago

Well, actually the problem was with you main method the whole time, but the tenRun method should probably check for nulls. The reason for this was because you were trying to print array[0] with an empty array, and that's what caused the error all along, so no, you have to check for it in main.

Meepo Over a year ago

No problem and good luck. BTW you can mark your question as answered so that way people know that they don't need to look at this question anymore.

arjunsv3691 · Accepted Answer · 2017-10-16 04:43:31Z

0

check the array length before printing or accessing elements in it, in your code at the end of main you are printing array element without check. include a check so that you can avoid this error , once tenRun returns an array check size of it

if(array.length > 0 )
{  int i;
   for(i = 0; i < array.length - 1; i++) 
       System.out.print(array[i] + ", ");
}
else
{
    System.out.println("Received empty array");
}

answered Oct 16, 2017 at 4:43

arjunsv3691

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