Removing specific value from array (java)

Question

i have integer a = 4 and array b 7,8,9,4,3,4,4,2,1

i have to write a method that removes int ALL a from array b

desired result 7,8,9,3,2,1

This is what I have so far,

    public static int[] removeTwo (int x, int[] array3)
{
    int counter = 0;
    boolean[] barray = new boolean [array3.length];
    for (int k=0; k<array3.length; k++)
    {
        barray[k] = (x == array3[k]);
        counter++;
    }

     int[] array4 = new int [array3.length - counter];
     int num = 0;
     for (int j=0; j<array3.length; j++)
{
     if(barray[j] == false)
    {
        array4[num] = array3[j];
        num++;
    }

}
     return array4;

I get this error

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at Utility.removeTwo(Utility.java:50)
    at Utility.main(Utility.java:18)

Java Result: 1

Any help would be much appreciated!

You're incrementing counter on each step through the first for loop, is that really what you mean? — Paul Rubel
– Paul Rubel, Commented Dec 9, 2013 at 14:21

turbo · Accepted Answer · 2013-12-09 15:03:14Z

2

The error stems from this for loop:

for (int k=0; k<array3.length; k++)
{
    barray[k] = (x == array3[k]);
    counter++;
}

when you create int[] array4 = new int [array3.length - counter]; you are creating an array with size 0. You should only increment the counter if the item is the desired item to remove:

for (int k=0; k<array3.length; k++)
{
    boolean b = (x == array3[k]);
    barray[k] = b;
    if(b) {
        counter++;
    }
}

To answer your question in the comment, the method should be called and can be checked like this:

public static void main(String[] args) {
    int[] array3 = {0,1,3,2,3,0,3,1};
    int x = 3;
    int[] result = removeTwo(x, array3);
    for (int n : result) {
        System.out.print(""+ n + " ");
    }
}

edited Dec 9, 2013 at 15:03

answered Dec 9, 2013 at 14:22

turbo

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4 Comments

user3083128 Over a year ago

It got rid of the error but i still got int x in my array int [] array3 = {0,1,3,2,3,0,3,1}; int x = 3; removeTwo(x,array3); for (int value : array3) System.out.printf("%d",value); Do I use that in my main method?

turbo Over a year ago

Use what in your main method? Why would you print the values of array3, which seems to be the original array?

user3083128 Over a year ago

wait nevermind, I wasn't thinking straight. hahaha I need sleep, thanks for your help!

turbo Over a year ago

Sure thing, it happens!

BobTheBuilder · Accepted Answer · 2013-12-09 14:20:20Z

1

On this line:

 int[] array4 = new int [array3.length - counter];

You create an array with size 0, as counter is equal to array3.length at this point.

This means that you cannot access any index in that array.

answered Dec 9, 2013 at 14:20

BobTheBuilder

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Comments

Ruchira Gayan Ranaweera · Accepted Answer · 2013-12-09 14:23:30Z

0

You are creating

int[] array4 = new int [array3.length - counter];// 0 length array.

you can't have 0th index there. At least length should 1 to have 0th index.

BTW my suggestion, it is better to use List. Then you can do this easy.

answered Dec 9, 2013 at 14:23

Ruchira Gayan Ranaweera

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Comments

Tim B · Accepted Answer · 2013-12-09 14:25:08Z

0

Really an Array is the wrong tool for the job, since quite apart from anything else you will end up with stray values at the end that you cannot remove. Just use an ArrayList and that provides a removeAll() method to do what you need. If you really need arrays you can even do:

List<Integer> list = new ArrayList(Arrays.asList(array))
list.removeAll(4);
array = list.toArray();

(Exact method names/parameters may need tweaking as that is all from memory).

answered Dec 9, 2013 at 14:25

Tim B

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4 Comments

Masudul Over a year ago

Is there any method removeAll(int) at List?

Tim B Over a year ago

int is a primitive object, you can't put that in a List

Stone Over a year ago

@TimB that's why he is using Integer

Tim B Over a year ago

@Stone I know, I was telling Masud :)

Stone · Accepted Answer · 2013-12-09 14:26:13Z

0

the simplest way is to work with a second array where you put in the correct values

something likte that

public static int[] removeTwo (int x, int[] array3)
{
    int counter = 0;
    int[] array4 = new int[array3.lenght];
    for (int i = 0; i < array3.lenght; i ++) {
       if(array3[i] == x){
           array4[counter] = array3[i];
       }
    }
    return array4;
}

anoterh way is to remove the x calue from the array3 and shift the values behind forward

answered Dec 9, 2013 at 14:26

Stone

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2 Comments

turbo Over a year ago

This code would not work, you never increment counter and you also misspelled length twice.

Stone Over a year ago

you are right sorry. after array4[counter] = array3[i]; you have to increment the counter counter += 1

Masudul · Accepted Answer · 2013-12-09 14:32:17Z

0

The best way to remove element from array is to use List with Iterator. Try,

 Integer[] array = {7, 8, 9, 4, 3, 4, 4, 2, 1};
 List<Integer> list = new ArrayList(Arrays.asList(array));
 for(Iterator<Integer> it=list.iterator();it.hasNext();){
     if(it.next()==4){
        it.remove();
      }
  }

answered Dec 9, 2013 at 14:32

Masudul

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