Getting next index in Java Integer array

Question

I am trying to search an array for an int but it only give the location of the first index it finds if the int appears more than once. For example, if the number 2 appears at index 3 and 7. It will say 3 found at location 3 twice instead of saying 2 found at location 3 and 7. How can I get the additional index of the location where the number also appears.

// random_integers is an array of random integers of size 10
Arrays.asList(random_integers);

for (int n : random_integers) {
    if (n == number) {
        System.out.println("Search Value: "
                + number
                + " found at location: "
                + Arrays.asList(random_integers).indexOf(n)
                + " in the unsorted array");
        }
    }

Thank you.

indexOf method prints first occurrence of object in list , not all. So In one iteration its difficult to get all indexes using arraylist — SacJn
– SacJn, Commented Oct 21, 2015 at 15:56

Michael · Accepted Answer · 2015-10-21 15:53:07Z

3

That's the behavior of indexOf. Instead, use a traditional for loop and just use the current looping variable

for (int i = 0; i < random_integers.length; i++){
    if (random_integers[i] == number){
        System.out.println("Search Value: " + number + " found at location: " + i);
    }
}

answered Oct 21, 2015 at 15:53

Michael

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Comments

Alex Salauyou · Accepted Answer · 2015-10-21 15:58:54Z

0

This happens because List#indexOf() has no idea about your intention to keep last index where item was found recently, so it returns first index every time. You should iterate over array by index, printing it when occurrence found:

for (int i; i < random_number.length; i++) {
    if (random_integers[i] == number) {
        System.out.format("Search Value: %s found at location: %s in the unsorted array", number, i);
    }
}

edited Oct 21, 2015 at 15:58

answered Oct 21, 2015 at 15:53

Alex Salauyou

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Comments

spenibus · Accepted Answer · 2015-10-21 16:24:34Z

0

The indexOf() method returns the index of the first occurrence of the specified element in the list, or -1 if the list does not contain the element.

A traditional for loop will work here.

for(int i=0; i < random_integers.length;i++){
    if (random_integers[i] == number){
        System.out.println("number=" + number + " location=" + i);
    }
}

edited Oct 21, 2015 at 16:24

spenibus

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answered Oct 21, 2015 at 16:12

Mandar_P

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Comments

user971961 · Accepted Answer · 2015-10-21 18:13:49Z

0

As what all guys said, use traditional for loop instead. If you want to use asList , try the following code:

   int size =  Arrays.asList(a).size();


 for (int i = 0 ; i < size ; i++){

     if (number == Arrays.asList(a).get(i))
 System.out.println("  Search Value: " + number +
            " found at location: " +        i +
            " in the unsorted array");
 }

answered Oct 21, 2015 at 18:13

user971961

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Comments

maazu · Accepted Answer · 2022-01-02 16:15:57Z

0

This code only works, if you are looking to find the current and next index value of a given array, however, if you are looking to find the index of a given value, refer to Michael's answer on this thread.

    int totalLength = random_integers.length;

    for (int i=0; i < totalLength; i++){
        int nextIndex = i+1;
        if (nextIndex == totalLength){
            break;
        }else{
           int currentIndexValue = random_integers[i];
           int nextIndexValue = random_integers[nextIndex];
        }
    }

edited Jan 2, 2022 at 16:15

answered Jan 2, 2022 at 15:49

maazu

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