Concurrent Modification Exception : adding to an ArrayList

Question

The problem occurs at

Element element = it.next();

And this code which contains that line, is inside of an OnTouchEvent

Answer 1

I solved creating a lock (Kotlin):

import java.util.concurrent.locks.ReentrantLock

Class A {
    private val listLock = ReentrantLock()
    fun doSomething(newElement){
        listLock.lock()
        list.add(newElement)
        listLock.unlock()
    }
}