ArrayList’s remove(object) giving IndexOutOfBoundsException

Question

Sorry if this has been asked before, but I haven’t been able to find anything that’s been helpful. Basically, when I add a bunch of characters to an ArrayList, and then try removing one of the characters, I get an IndexOutOfBoundsException, and I don’t understand why. Here's sort of a general example of what I am talking about.

public void addChars(){
    ArrayList<Character> chars = new ArrayList<Character>();
    word = "hello";
    chars.add(word.charAt(0));
    chars.add(word.charAt(1));
    chars.add(word.charAt(2));
    chars.add(word.charAt(3));
    chars.add(word.charAt(4));

    chars.remove(word.charAt(1));
}

which gives the following error

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 101, Size: 5
at java.util.ArrayList.rangeCheck(ArrayList.java:653)
at java.util.ArrayList.remove(ArrayList.java:492)
at trial.addChars(trial.java:26)
at trial.main(trial.java:31)

I don't understand how I can be getting an IndexOutOfBoundsException when I'm trying to remove a character, shouldn't java look through my ArrayList "chars", and either remove or not remove depending on if the character is present?

If I alter this code to remove a character that is not present in my ArrayList it works fine, it is only when I try removing a character that is in the ArrayList that things break down.

Thanks!

Sounds like `char` is been treated as `int`, which would make `e` `101`...maybe try `chars.remove((Character)word.charAt(1));` instead... — MadProgrammer, Jul 01 '15 at 02:36

Teddy Koker · Answer 1 · 2015-07-01T02:42:35.500

1

chars.remove((Character)word.charAt(1));

The ArrayList.remove() method can also take an integer index. Try:

chars.remove(chars.indexOf(word.charAt(1)));

edited Jul 01 '15 at 02:42

answered Jul 01 '15 at 02:40

Teddy Koker

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http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html#remove(java.lang.Object) – dting Jul 01 '15 at 02:41
3

Then what's [`ArrayList#remove(Object)`](http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html#remove(java.lang.Object))? I must have been doing it wrong all these years :P – MadProgrammer Jul 01 '15 at 02:42
remove() is interpreting the argument as an integer not an object – Rondo Jul 01 '15 at 02:48
Hence the cast to a character in the first excerpt of code – Teddy Koker Jul 01 '15 at 02:50

ArrayList’s remove(object) giving IndexOutOfBoundsException

1 Answers1