Collection<Integer> c = new ArrayList<>(); ArrayList<Integer> list = (ArrayList<Integer>) c; // =========================================================== Collection<Integer> values = new HashMap<Integer,Integer> ().values(); ArrayList<Integer> list1 =(ArrayList<Integer>) values;
输出:Exception in thread "main" java.lang.ClassCastException: java.base/java.util.HashMap$Values cannot be cast to java.base/java.util.ArrayList