Use String.isEmpty() instead of comparing to ""

Use of String.equals("") can be replaced with with String.length() == 0
(for JDK5 and lower) or String.isEmpty() (for JDK6 and higher)

Change-Id: Id1462d22c5d249485d87993263a9239809e73c55
Signed-off-by: Carsten Hammer <carsten.hammer@t-online.de>
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/TestRepository.java

 				firstParentId = parents.get(0);
 
 			ObjectId cid;
-			if (changeId.equals(""))
+			if (changeId.isEmpty())
 				cid = ChangeIdUtil.computeChangeId(c.getTreeId(), firstParentId,
 						c.getAuthor(), c.getCommitter(), message);
 			else

org.eclipse.jgit.pgm.test/src/org/eclipse/jgit/lib/CLIRepositoryTestCase.java

 	protected void assertStringArrayEquals(String expected, String[] actual) {
 		// if there is more than one line, ignore last one if empty
 		assertEquals(1,
-				actual.length > 1 && actual[actual.length - 1].equals("")
+				actual.length > 1 && actual[actual.length - 1].isEmpty()
 						? actual.length - 1 : actual.length);
 		assertEquals(expected, actual[0]);
 	}

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Blame.java

 			}
 		}
 
-		if (beginStr.equals("")) //$NON-NLS-1$
+		if (beginStr.isEmpty())
 			begin = 0;
 		else if (beginStr.startsWith("/")) //$NON-NLS-1$
 			begin = findLine(0, beginStr);
 		else
 			begin = Math.max(0, Integer.parseInt(beginStr) - 1);
 
-		if (endStr.equals("")) //$NON-NLS-1$
+		if (endStr.isEmpty())
 			end = blame.getResultContents().size();
 		else if (endStr.startsWith("/")) //$NON-NLS-1$
 			end = findLine(begin, endStr);

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Main.java

 			if (s == null && protocol.equals("https")) { //$NON-NLS-1$
 				s = System.getenv("HTTPS_PROXY"); //$NON-NLS-1$
 			}
-			if (s == null || s.equals("")) { //$NON-NLS-1$
+			if (s == null || s.isEmpty()) {
 				continue;
 			}
 

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Status.java

 		if (!porcelain) {
 			outw.println(CLIText.formatLine(MessageFormat.format(pattern,
 					arguments)));
-			if (!pattern.equals("")) //$NON-NLS-1$
+			if (!pattern.isEmpty())
 				outw.println(CLIText.formatLine("")); //$NON-NLS-1$
 			outw.flush();
 		}

org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java

 								if (!(rev instanceof RevBlob))
 									throw new IncorrectObjectTypeException(rev,
 											Constants.TYPE_BLOB);
-							} else if (item.equals("")) { //$NON-NLS-1$
+							} else if (item.isEmpty()) {
 								rev = rw.peel(rev);
 							} else
 								throw new RevisionSyntaxException(revstr);
 					if (time.equals("upstream")) { //$NON-NLS-1$
 						if (name == null)
 							name = new String(revChars, done, i);
-						if (name.equals("")) //$NON-NLS-1$
+						if (name.isEmpty())
 							// Currently checked out branch, HEAD if
 							// detached
 							name = Constants.HEAD;
 					} else {
 						if (name == null)
 							name = new String(revChars, done, i);
-						if (name.equals("")) //$NON-NLS-1$
+						if (name.isEmpty())
 							name = Constants.HEAD;
 						if (!Repository.isValidRefName("x/" + name)) //$NON-NLS-1$
 							throw new RevisionSyntaxException(MessageFormat
 				if (rev == null) {
 					if (name == null)
 						name = new String(revChars, done, i);
-					if (name.equals("")) //$NON-NLS-1$
+					if (name.isEmpty())
 						name = Constants.HEAD;
 					rev = parseSimple(rw, name);
 					name = null;