Copyonwritearraylist Operation Java.lang.UnsupportedOperationException

Problem One: Copyonwritearraylist cannot be cast to ArrayList
Workaround: Pass copyonwritearraylist into the ArrayList
ArrayList<T> arrayList = new ArrayList<T>(list);

Issue two: Copyonwritearraylist does not support Collections.sort
The workaround:

new ArrayList<T>(list);        Collections.sort（arrayList ，new Comparator<T>() {            publicintcompare(T o1, T o2) {}       }）；

Question three: Copyonwritearraylist does not support
while (Iterator.hasnext ()) {
Iterator.remove ();
}
Reason: Copyonwritearraylist did a "snapshot" before doing the iteration, so the ITER is immutable at this point, that is to say that calling Iter.remove () in this traversal throws an exception
The workaround:

        CopyOnWriteArrayList<T> t1 ;        Iteratoriterator = t1.iterator();        while (iterator{                T t= iterator.next();                t1.remove(t);            }

Copyonwritearraylist Operation Java.lang.UnsupportedOperationException