how to find an element in an array

**humdinger** · April 8th, 2010, 02:41 PM

Hi guys,

Im trying to write a very small and simple method that will find an element from a arrayList and return it. the list contains instances of a class called People. I tried using the indexOf method to find the index of the desired element and then the get() method to return the element using the previously found index.

I just keep getting the java.lang.ArrayIndexOutOfBoundsException: -1 error.

the code I have is:

public Names findPerson(String aString)
   {
      int personIndex = people.lastIndexOf(aString);
      return people..get(personIndex);
   }

any help is much appreciated.

**helloworld922** · April 8th, 2010, 06:34 PM

any of the indexOf methods (first, last, etc.) return -1 if the string was not found.

**humdinger** · April 9th, 2010, 01:46 AM

ok thankyou for the advice, i know the string is in there so I will do some testing on this later. Does anyone have any ideas?

**Bryan** · April 9th, 2010, 03:59 AM

Have you considered using Hashtables?

**humdinger** · April 9th, 2010, 04:14 AM

Hi, i thought about tthat but as I only have an arrayList with all the People objects stored in it Im not sure it would work as I have nothing to use as keys. I will definately look into it in more detail later though. Im unable to do it now as im at work & not with my computer. Thankyou for the advice

**Bryan** · April 9th, 2010, 04:47 AM

Doesn't your People object has a id? something along the way of peopleId.

I'm using a Hastable with User objects in it, and my userid is the key in the Hashtable, that way I can easy find users based on their id

**humdinger** · April 9th, 2010, 07:54 AM

ok great il give it a try when i get home
thanks again

**humdinger** · April 9th, 2010, 11:16 AM

it works!!! thankyou Brian, I cant believe I didnt think of that before! silly me

**Bryan** · April 9th, 2010, 05:22 PM

No problem, I just started learning Java and also had to deal with the same problem that you had.

I first solved it by making my own get(id) and then iterate through the array and comparing the id with the object->getID(). But I refused to believe Java didn't had a better solution for this so I went through the documentation and found it

Thread: how to find an element in an array

LinkBack

Thread Tools

Display

how to find an element in an arrayList

Related threads:

Re: how to find an element in an array

The Following User Says Thank You to helloworld922 For This Useful Post:

Re: how to find an element in an array

Re: how to find an element in an array

Re: how to find an element in an array

Re: how to find an element in an array

The Following User Says Thank You to Bryan For This Useful Post:

Re: how to find an element in an array

Re: how to find an element in an array

Re: how to find an element in an array

Similar Threads

FAQ: find variable in an array of objects

new arrayList element overwrites all previous

Add white spices before the String element

[SOLVED] theory behind testing each element of an array.

How to extract a particular element details which has more references ???