how to code a java method that retrieve a given index value?

Question

// this this the orginal code:

public void searchBird (int indexPosition) {
    Bird bird = birdList.get(indexPosition);
    System.out.println ("Art:" + bird.getArt ());
    System.out.println ("Location:" + bird.getLocation ());
}

I have so far tried to code a method which returns one element out of the ArrayList with a given index as a parameter. I get an error message when I send in, for example 5, as a parameter.

// and this is what i tried:

public void searchBird (int indexPosition) {
    Bird bird = birdList.get(indexPosition);
    for (int i = 0; i <bird list.size (); i ++) {
        if ((birdList.contains(indexPosition))) {
            System.out.println ("Art:" + bird.getArt ());
            System.out.println ("Location:" + bird.getLocation ());
        }
    }
}

this is what i get;

java.lang.IndexOutOfBoundsException: Index: 5, Size: 3 when calling the method with 5 as a parameter

Please verify the code you posted. Your if statement `for (int i = 0; i — Korashen, Aug 16 '18 at 12:13
Your array has 3 items and you are trying to get the 6th item in it.. Check if the size is smaller than given index and return gracefully — Jokkeri, Aug 16 '18 at 12:13
If `birdList` is a list of `Bird` objects, why would you expect it to contain `indexPosition`, an integer? — khelwood, Aug 16 '18 at 12:18

deHaar · Accepted Answer · 2018-08-16T12:43:50.187

0

You are not checking if the given index (indexPosition) is valid in your birdList. If you give an index that is larger than the last index of the list, then you get the IndexOutOfBoundsException you have seen.

Try a little check before calling birdList.get(indexPosition) and skip the entire for loop, you don't need it. Additionally, you should not pass an index to the contains method because it looks for objects, not for indexes (if you have a defined Bird, you can try birdList.contains(bird)).

public void searchBird(int indexPosition) {
    // there might be the following case: indexPosition > maximum index of birdList
    if (indexPosition < birdList.size()) {
        Bird bird = birdList.get(indexPosition);
        System.out.println("Art:" + bird.getArt());
        System.out.println("Location:" + bird.getLocation());
    } else {
        System.out.println("The given index exceeds the list of birds!");
    }
}

edited Aug 16 '18 at 12:43

answered Aug 16 '18 at 12:17

deHaar

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That should have bothered you: `if (birdList.contains(indexPosition))` – jhamon Aug 16 '18 at 12:33
Yes, you are right... I will adjust my answer accordingly! Thanks! – deHaar Aug 16 '18 at 12:38
@dehaar thank you so much for your help , your answer was really helpful and the method works good now! – Kevin Sted Aug 16 '18 at 13:00
@SadeerThaer No problem, you are welcome. – deHaar Aug 16 '18 at 13:00

how to code a java method that retrieve a given index value?

1 Answers1