java super vs extends

最新推荐文章于 2025-05-07 12:38:27 发布

转载最新推荐文章于 2025-05-07 12:38:27 发布 · 586 阅读

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extends:
  List<? extends Number> foo3 = new ArrayList();  // Number "extends" Number (in this context)
  List<? extends Number> foo3 = new ArrayList(); // Integer extends Number
  List<? extends Number> foo3 = new ArrayList();  // Double extends Number
super:
  List<? super Integer> foo3 = new ArrayList();  // Integer is a "superclass" of Integer (in this context)
  List<? super Integer> foo3 = new ArrayList();   // Number is a superclass of Integer
  List<? super Integer> foo3 = new ArrayList();   // Object is a superclass of Integer

Producer Extends, Consumer Super.