RFR: JDK-8062849 -- Optimize EnumMap.equals

[Brent Christian]

Looks reasonable to me.
-Brent

On 7/28/15 9:14 AM, Steve Drach wrote:
> Please review the following simple fix for the issue reported in https://bugs.openjdk.java.net/browse/JDK-8062849 <https://bugs.openjdk.java.net/browse/JDK-8062849>.
>
> -----------------
> # HG changeset patch
> # User sdrach
> # Date 1437777193 25200
> #      Fri Jul 24 15:33:13 2015 -0700
> # Node ID e57b1569a65ec4dc8c749dedd3345abe5d493054
> # Parent  4dd09cb5f7c2a2a23a9958ea7a602dd74d5709b2
> 8062849: Optimize EnumMap.equals
> Summary: In the equals method, if the two EnumMaps are a different size return false since they can't be equal.
> Reviewed-by: brent.christian at oracle.com, paul.sandoz at oracle.com
> Contributed-by: steve.drach at oracle.com
>
> diff --git a/src/java.base/share/classes/java/util/EnumMap.java b/src/java.base/share/classes/java/util/EnumMap.java
> --- a/src/java.base/share/classes/java/util/EnumMap.java
> +++ b/src/java.base/share/classes/java/util/EnumMap.java
> @@ -681,8 +681,11 @@
>       }
>
>       private boolean equals(EnumMap<?,?> em) {
> +        if (size != em.size)
> +            return false;
> +
>           if (em.keyType != keyType)
> -            return size == 0 && em.size == 0;
> +            return size == 0;
>
>           // Key types match, compare each value
>           for (int i = 0; i < keyUniverse.length; i++) {
>