My Java application crashes because of this method

Question

My application crashes because of this method. Please help :=)

public void sortedList() {
    String goodLetter = "B";

    for (String myItem : myArrayList) {
        String myFirstChar = myItem.substring(0, 1);
        if (myFirstChar != goodLetter) {
            myArrayList.remove(myItem);
        }
    }
}

The least you could do is provide the stack trace for the crash — Willy Wonka, Jan 16 '19 at 15:59
regardless of the error, consider using the equals() method for String comparison, as you want to compare the values of the objects, not the objects themselves — Nikos Hidalgo, Jan 16 '19 at 16:03

score 3 · Accepted Answer · answered Jan 16 '19 at 16:07

3

Your code will crash if:

myArrayList contains a null element (NullPointerException)
myArrayList contains the empty String (IndexOutOfBoundsException)
Any element from myArrayList does not start with "B" (ConcurrentModificationException)

For that last, and most probable, cause see the question linked by @Todd in the comments.

Additionally, in Java you should compare Strings using .equals instead of == or !=.

answered Jan 16 '19 at 16:07

RobCo

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You could consider immediately switching over to [Kotlin](https://kotlinlang.org/docs/reference/), where once again it is fine to compare Strings using `==` ;) – RobCo Jan 16 '19 at 16:18
Exactly because of the bug in string comparison it will probably crash with a word that does start with `B` too. – Ole V.V. Jan 16 '19 at 16:55

score 0 · Answer 2 · answered Jan 16 '19 at 16:04

0

First, for string comparison, use String.equals() and not ==. Second, if you want to remove objects from a list :

do a reverse browsing
or create an intermediary array containing objects to remove

answered Jan 16 '19 at 16:04

Bruno

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My Java application crashes because of this method

2 Answers2