RFR: 8258422: Cleanup unnecessary null comparison before instanceof check in java.base [v3]

[Andrey Turbanov]

On Wed, 16 Dec 2020 18:27:35 GMT, Aleksei Efimov <aefimov at openjdk.org> wrote:

>> Let's take advantage of "flow scoping" to eliminate some of these casts. A few examples follow.
>
> Hi Andrey,
> 
> Could you, please, also take a look at `java.net.Socket`:
> java/net/Socket.java:        if (bindpoint != null && (!(bindpoint instanceof InetSocketAddress)))
> java/net/Socket.java-            throw new IllegalArgumentException("Unsupported address type");
> And `HttpURLConnection`:
>     sun/net/www/protocol/http/HttpURLConnection.java:                    if (a != null && c instanceof HttpURLConnection) {
>     sun/net/www/protocol/http/HttpURLConnection.java-                        ((HttpURLConnection)c).setAuthenticator(a);
> The following cmd was used to find them: `rgrep -A 1 "= null .* instanceof "`

@AlekseiEfimov in both cases removing `null` check will change semantic of the code. Comparison is not redundant.

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PR: https://git.openjdk.java.net/jdk/pull/20