Re: JDK 10 RFR of 8182710: File.listRoots() always returns the root of CD drive

[Roger Riggs]

Pretty code; though the part about creating an array to create a BitSet 
is a bit non-obvious.

But how much garbage does it create and extra runtime doing all that 
fancy stuff.

Now if BitSet had a constructor from the bits in a long...

Roger


On 6/29/2017 3:25 AM, Langer, Christoph wrote:
Looks good.

Best regards
Christoph

-----Original Message-----
From: core-libs-dev [mailto:core-libs-dev-boun...@openjdk.java.net] On
Behalf Of Brian Burkhalter
Sent: Mittwoch, 28. Juni 2017 19:49
To: core-libs-dev <core-libs-dev@openjdk.java.net>
Subject: Re: JDK 10 RFR of 8182710: File.listRoots() always returns the root of
CD drive

I rather like that. How about this (without "ds")?

     public File[] listRoots() {
         return BitSet
             .valueOf(new long[] {listRoots0()})
             .stream()
             .mapToObj(i -> new File((char)('A' + i) + ":" + slash))
             .filter(f -> access(f.getPath()) && f.exists())
             .toArray(File[]::new);
     }

Thanks,

Brian

On Jun 27, 2017, at 10:54 PM, Tagir Valeev <amae...@gmail.com> wrote:

Just an alternative which looks more readable to me (no explicit bit
twiddling):
-        int ds = listRoots0();
-        return IntStream
-            .range(0, 26)
-            .filter(i -> ((ds >> i) & 1) != 0)
+       long[] ds = {listRoots0()};
+       return BitSet
+            .valueOf(ds)
+            .stream()

Probably a matter of taste though.