Java : Exception in thread "main" java.util.ConcurrentModificationException
When Exception in thread "main" java.util.ConcurrentModificationException occurs.
package com.ekiras.demo;
import java.util.ArrayList;
import java.util.List;
public class Test {
public static void main(String args[]){
// create a new list
List<String> list = new ArrayList<String>();
// add 50 items to the list
for(int itr=0;itr<50;itr++)
list.add("user-"+(itr+1));
// try to remove item from list while iterating the list
for(String str : list){
if(str.equals("user-15")){
list.remove(str);
}
}
}
}
The above code will give the following error.
Exception in thread "main" java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859) at java.util.ArrayList$Itr.next(ArrayList.java:831) at testing.Test.main(Test.java:18)
How to avoid ConcurrentModificationException
- Create the list of type CopyOnWriteArrayList, this will create a new copy of list for every operation performed and then replace it with original.
List<String> list = new CopyOnWriteArrayList<String>();
- Create a new copy of the list for iterating the list
for(String str : new ArrayList<String>(list))
- Use the Iterator to iterate the list and modify its contents.
Iterator<String> iterator = list.iterator(); while(iterator.hasNext()){ String str = iterator.next(); if(str.equals("user-15")){ iterator.remove(); } }
Java : Exception in thread "main" java.util.ConcurrentModificationException
![Java : Exception in thread "main" java.util.ConcurrentModificationException]()
Reviewed by Ekansh Rastogi
on
19:28
Rating: 5