super keyword in generics

Asked Jun 16 '14 at 19:50

Active Jun 16 '14 at 20:13

Viewed 44 times

  Set<? super TreeMap> setOfAllSuperTypeOfTreeMap  = new HashSet<SortedMap>();

  SortedMap<String,String> sm = new TreeMap<String,String>();
  TreeMap<String,String> tm = new TreeMap<String,String>();
  setOfAllSuperTypeOfTreeMap.add(sm); //???I do not understand at all. How then could new HashSet<SortedMap> be ok?
  setOfAllSuperTypeOfTreeMap.add(tm);

I do not understand at all. How then could new HashSet be declared at all? And what good does it do since SortedMaps can not be added anyway.

edited Jun 16 '14 at 20:13

asked Jun 16 '14 at 19:50

Paul

watch this: https://www.youtube.com/watch?v=V1vQf4qyMXg#t=1339 – Alexandre Santos Jun 16 '14 at 19:54
Did the duplicate answer your question? – awksp Jun 16 '14 at 20:17

super keyword in generics

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