How to make List read-only

Sometimes we need that no element should be added or deleted from our collections.

Then we should follow this stratigity

List<String> list=new ArrayList<>();

fillDataInList(list);

list = Collections.unmodifiableList(list);

simillary for set and map

set=Collections.unmodifiableSet(set);

map = Collections.unmodifiableMap(map);

And remember  if you try to add element  this will not give compiler error but java.lang.UnsupportedOperationException

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