src/java.base/share/classes/java/lang/Class.java

*** 57,66 ****
--- 57,68 ----
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.StringJoiner;
+ import java.util.stream.Stream;
+ import java.util.stream.Collectors;
  
  import jdk.internal.HotSpotIntrinsicCandidate;
  import jdk.internal.loader.BootLoader;
  import jdk.internal.loader.BuiltinClassLoader;
  import jdk.internal.misc.Unsafe;
*** 198,208 ****
       * The string is formatted as a list of type modifiers, if any,
       * followed by the kind of type (empty string for primitive types
       * and {@code class}, {@code enum}, {@code interface}, or
       * <code>@</code>{@code interface}, as appropriate), followed
       * by the type's name, followed by an angle-bracketed
!      * comma-separated list of the type's type parameters, if any.
       *
       * A space is used to separate modifiers from one another and to
       * separate any modifiers from the kind of type. The modifiers
       * occur in canonical order. If there are no type parameters, the
       * type parameter list is elided.
--- 200,211 ----
       * The string is formatted as a list of type modifiers, if any,
       * followed by the kind of type (empty string for primitive types
       * and {@code class}, {@code enum}, {@code interface}, or
       * <code>@</code>{@code interface}, as appropriate), followed
       * by the type's name, followed by an angle-bracketed
!      * comma-separated list of the type's type parameters, if any,
!      * including informative bounds on the type parameters, if any.
       *
       * A space is used to separate modifiers from one another and to
       * separate any modifiers from the kind of type. The modifiers
       * occur in canonical order. If there are no type parameters, the
       * type parameter list is elided.
*** 260,283 ****
                  sb.append(getName());
              }
  
              TypeVariable<?>[] typeparms = component.getTypeParameters();
              if (typeparms.length > 0) {
!                 StringJoiner sj = new StringJoiner(",", "<", ">");
!                 for(TypeVariable<?> typeparm: typeparms) {
!                     sj.add(typeparm.getTypeName());
!                 }
!                 sb.append(sj.toString());
              }
  
              for (int i = 0; i < arrayDepth; i++)
                  sb.append("[]");
  
              return sb.toString();
          }
      }
  
      /**
       * Returns the {@code Class} object associated with the class or
       * interface with the given string name.  Invoking this method is
       * equivalent to:
       *
--- 263,294 ----
                  sb.append(getName());
              }
  
              TypeVariable<?>[] typeparms = component.getTypeParameters();
              if (typeparms.length > 0) {
!                 sb.append(Stream.of(typeparms).map(t -> typeVarBounds(t)).
!                           collect(Collectors.joining(",", "<", ">")));
              }
  
              for (int i = 0; i < arrayDepth; i++)
                  sb.append("[]");
  
              return sb.toString();
          }
      }
  
+     String typeVarBounds(TypeVariable<?> typeVar) {
+         Type[] bounds = typeVar.getBounds();
+         if (bounds.length == 1 && bounds[0].equals(Object.class)) {
+             return typeVar.getName();
+         } else {
+             return typeVar.getName() + " extends " +
+                 Stream.of(bounds).map(e -> e.getTypeName()).
+                 collect(Collectors.joining(" & "));
+         }
+     }
+ 
      /**
       * Returns the {@code Class} object associated with the class or
       * interface with the given string name.  Invoking this method is
       * equivalent to:
       *