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In Java, how do I convert List<?> to List<T> using a general purpose method so that I can replace patterns like the following with a single method call: List untypedList = new ArrayList(); // or returned from a legacy method List<Integer> typedList = new ArrayList<Integer>(); for (Object item: untypedList) typedList.add((Integer)item); Note that the above code does not generate any type-safety warnings and, ideally, your solution shouldn't generate any such warnings, either. Will the following solution work provided that list Class<L> has a public default constructor? public class ListUtil { public static <T, L extends List<T>> L typedList(List<?> untypedList, Class<T> itemClass, Class<L> listClass) { L list = null; try { list = listClass.newInstance(); } catch (InstantiationException e) { } catch (IllegalAccessException e) { } for (Object item: untypedList) list.add(itemClass.cast(item)); return list; } } (Note that listClass.newInstance() throws InstantiationException or IllegalAccessException if an instance of Class<L> does not have a public default constructor. What problems may arise if the method does not properly handle these exceptions?) Notes: T is the type of each item in the resulting list. L is the type of the list that I wish to create (which extends List<T> ). untypedList is the "untyped" input list, effectively the same as List<Object> . itemClass represents the runtime class of T . listClass represents the runtime class of L .

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