8276904: Optional.toString() is unnecessarily expensive

Reviewed-by: rriggs, smarks

Author: Eamonn McManus

src/java.base/share/classes/java/util/Optional.java

@@ -454,7 +454,7 @@ public int hashCode() {
     @Override
     public String toString() {
         return value != null
-            ? String.format("Optional[%s]", value)
+            ? ("Optional[" + value + "]")
             : "Optional.empty";
     }
 }

src/java.base/share/classes/java/util/OptionalDouble.java

@@ -328,7 +328,7 @@ public int hashCode() {
     @Override
     public String toString() {
         return isPresent
-                ? String.format("OptionalDouble[%s]", value)
+                ? ("OptionalDouble[" + value + "]")
                 : "OptionalDouble.empty";
     }
 }

src/java.base/share/classes/java/util/OptionalInt.java

@@ -326,7 +326,7 @@ public int hashCode() {
     @Override
     public String toString() {
         return isPresent
-                ? String.format("OptionalInt[%s]", value)
+                ? ("OptionalInt[" + value + "]")
                 : "OptionalInt.empty";
     }
 }

src/java.base/share/classes/java/util/OptionalLong.java

@@ -326,7 +326,7 @@ public int hashCode() {
     @Override
     public String toString() {
         return isPresent
-                ? String.format("OptionalLong[%s]", value)
+                ? ("OptionalLong[" + value + "]")
                 : "OptionalLong.empty";
     }
 }