Aug 3, 2011 | Java, Uncategorized
Your program throws ConcurrentModificationException while running and how can you prevent / solve it It happens when your program removing an item in an ArrayList, Collection or List while looping (iterating) over it. Example: for (int i = 0; i < yourArrayList.size(); i++) { if (yourArrayList.get(i).compareToIgnoreCase("apple") == 0) { yourArrayList.remove(i); } } //Exception in thread "main" java.util.ConcurrentModificationException // at java.util.AbstractList$Itr.checkForComodification(Unknown Source) // at java.util.AbstractList$Itr.next(Unknown Source) To prevent this, there are several solutions depending on you program logic. Solution 1 – Using the java.util.Iterator: import java.util.Iterator; ... Iterator<String> iterator = yourArrayList.iterator(); while (iterator.hasNext()) { String string = (String) iterator.next(); if (string.compareToIgnoreCase("apple") == 0) { iterator.remove(); } } Solution 2 – Using an temporary ArrayList to store items for removal: //Initialize an temporary array list with similar type ArrayList<String> itemToRemove = new ArrayList<String>(); //Search for items matching string "apple" for (int i = 0; i < yourArrayList.size(); i++) { if (yourArrayList.get(i).compareToIgnoreCase("apple") == 0) { itemToRemove.add(yourArrayList.get(i)); } } //Remove items stored in itemToRemove ArrayList yourArrayList.removeAll(itemToRemove); Hope it...
