[JGIT PATCH 09/13] Replace inefficient new String(String) constructor to silence FindBugs

FindBugs keeps reporting that our usage of new String(String)
is not the most efficient way to construct a string.

http://thread.gmane.org/gmane.comp.version-control.git/113739/focus=113787

I had a specific reason for forcing a new String object here.

The line in question, p, is from the packed-refs file and
contains the entire SHA-1 in hex form at the beginning of it.
We've converted that into binary as an ObjectId, it uses 1/4 the
space of the string portion.

The Ref object, its ObjectId, and its name string, are going to be
cached in a Map, probably long-term.  We're better off shedding the
80 bytes of memory used to hold the hex SHA-1 then risk substring()
deciding its "faster" to reuse the char[] then to make a copy of it.

Another way to force this new unique String instance with its own
private char[] is to use a StringBuilder and append onto it the
ref name.  This shouldn't be a warning for FindBugs, but it would
accomplish the same goal of producing 1 clean copy, with no extra
transient temporary array.

Signed-off-by: Shawn O. Pearce <redacted>
CC: Yann Simon <redacted>
CC: Matthias Sohn <redacted>
---
 .../src/org/spearce/jgit/lib/RefDatabase.java      |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java b/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java
index 87f26bf..bccf2d0 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java

@@ -447,7 +447,8 @@ private synchronized void refreshPackedRefs() {
 
 					final int sp = p.indexOf(' ');
 					final ObjectId id = ObjectId.fromString(p.substring(0, sp));
-					final String name = new String(p.substring(sp + 1));
+					final String name = new StringBuilder(p.length() - (sp + 1))
+							.append(p, sp + 1, p.length()).toString();
 					last = new Ref(Ref.Storage.PACKED, name, name, id);
 					newPackedRefs.put(last.getName(), last);
 				}

-- 
1.6.3.rc1.205.g37f8