Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-6557661

Problem with least upper bound

    XMLWordPrintable

Details

    • generic
    • generic

    Description

      One of these assignments should fail:

      import java.util.*;

      public class X {
          <T> Map<T,T> foo(T t1, T t2, T t3) {
              return null;
          }
          <U extends Object, V extends U> void bar(U u, V v, List<? extends V> lv) {
              Map<Object,Object> map1 = foo(u, v, lv.get(0));
              Map<U,U> map2 = foo(u, v, lv.get(0));
          }
      }

      X.java:9: incompatible types
      found : java.util.Map<java.lang.Object,java.lang.Object>
      required: java.util.Map<U,U>
              Map<U,U> map2 = foo(u, v, lv.get(0));
                                 ^
      1 error

      javac rejects the latter which seems incorrect. Eclipse gets it the
      other way around.

      Similar problem with this example:

      import java.util.*;

      public class X {
          <T> Map<T,T> foo(T t1, T t2, T t3) {
              return null;
          }
          <U extends Object, V extends U> void bar(U u, V v) {
              Map<Object,Object> map1 = foo(u, v, null);
              Map<U,U> map2 = foo(u, v, null);
          }
      }

      X.java:9: incompatible types
      found : java.util.Map<java.lang.Object,java.lang.Object>
      required: java.util.Map<U,U>
              Map<U,U> map2 = foo(u, v, null);
                                 ^
      1 error

      And:

      import java.util.*;

      public class X {
          <T> Map<T,T> foo(T t1, T t2) {
              return null;
          }
          <U extends Object, V extends U> void bar(U u, V v) {
              Map<Object,Object> map1 = foo(u, v);
              Map<U,U> map2 = foo(u, v);
          }
      }

      X.java:9: incompatible types
      found : java.util.Map<java.lang.Object,java.lang.Object>
      required: java.util.Map<U,U>
              Map<U,U> map2 = foo(u, v);
                                 ^
      1 error

      Attachments

        Issue Links

          Activity

            People

              Unassigned Unassigned
              ahe Peter Ahe
              Votes:
              0 Vote for this issue
              Watchers:
              0 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:
                Imported:
                Indexed: