You can clone() it: Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/util/ArrayList.html#clone()
Before using sort() on it: Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/util/List.html#sort(java.util.Comparator)
W/ a Comparator: Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/util/Comparator.html#compare(T,T)