I want to check if index of ArrayList is declared, without using get

Question

I try to get an element from an Arraylist using an index, and check if it is empty or not.

I tried:

if(!ArrayList.get(index)) {
    // do something
}

And it gets Index out of Bounds exception.

Of course I can use try-catch, but I'd like to know if there is any other way of doing this without using try-catch?

I think I can do it more simply, but I can't. I tried to read the API documentation, but it seems like there is no such thing as what I want to do.

oh and, i tryed if(ArrayList.get(index)==null) ... and it also stop by error! — ChangWon Jeong Juicycool, Feb 20 '17 at 13:05
Is your `ArrayList` *instance* called `ArrayList`? How confusing. — Biffen, Feb 20 '17 at 13:07

Mureinik · Accepted Answer · 2017-02-20T13:08:32.107

2

You could just check the list's size() (and of course, it must also be non-negative):

if (index >= 0 && index < myList.size()) {
    // Do something with myList.get(index)
}

edited Feb 20 '17 at 13:08

answered Feb 20 '17 at 13:06

Mureinik

1

myList.size() > index – Maurice Perry Feb 20 '17 at 13:07
oh boi, i am idiot... ill accept answer after 10minuate! – ChangWon Jeong Juicycool Feb 20 '17 at 13:08
@MauricePerry grr... stupid typo. Thanks for noticing! – Mureinik Feb 20 '17 at 13:08

score 1 · Answer 2 · answered Feb 20 '17 at 13:08

1

if(index < ArrayList.size() && ArrayList.get(index) != null)

answered Feb 20 '17 at 13:08

Michael Dz

okay, i tryed to reverse like : if (index > ArrayList.size() && ArrayList.get(index) == null) and its crashed, hmm did i typo? – ChangWon Jeong Juicycool Feb 20 '17 at 13:15
1

@ChangWonJeongJuicycool If `index > ArrayList.size()` then `ArrayList.get(index)` won't *ever* return `null` or even anything *comparable to* `null`. – Biffen Feb 20 '17 at 13:25
@Biffen ahh, thats why i got error when try to get() wrong index? cool! if it is, now im perfectly understand, thanks to you! – ChangWon Jeong Juicycool Feb 20 '17 at 13:33

2 Answers2