Use try-with-resource to close resources in CheckoutCommand

Change-Id: Ia4d4f9bff03a03d116b80022d7691df67bf8b51b
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java

@@ -208,7 +208,7 @@ public class CheckoutCommand extends GitCommand<Ref> {
 			}
 
 			if (createBranch) {
-				Git git = new Git(repo);
+				try (Git git = new Git(repo)) {
 					CreateBranchCommand command = git.branchCreate();
 					command.setName(name);
 					if (startCommit != null)
@@ -219,6 +219,7 @@ public class CheckoutCommand extends GitCommand<Ref> {
 						command.setUpstreamMode(upstreamMode);
 					command.call();
 				}
+			}
 
 			Ref headRef = repo.getRef(Constants.HEAD);
 			String shortHeadRef = getShortBranchName(headRef);
@@ -243,11 +244,14 @@ public class CheckoutCommand extends GitCommand<Ref> {
 							JGitText.get().refNotResolved, name));
 			}
 
-			RevWalk revWalk = new RevWalk(repo);
+			RevCommit headCommit = null;
+			RevCommit newCommit = null;
+			try (RevWalk revWalk = new RevWalk(repo)) {
 				AnyObjectId headId = headRef.getObjectId();
-			RevCommit headCommit = headId == null ? null : revWalk
+				headCommit = headId == null ? null
-					.parseCommit(headId);
+						: revWalk.parseCommit(headId);
-			RevCommit newCommit = revWalk.parseCommit(branch);
+				newCommit = revWalk.parseCommit(branch);
+			}
 			RevTree headTree = headCommit == null ? null : headCommit.getTree();
 			DirCacheCheckout dco;
 			DirCache dc = repo.lockDirCache();
@@ -376,26 +380,20 @@ public class CheckoutCommand extends GitCommand<Ref> {
 	 */
 	protected CheckoutCommand checkoutPaths() throws IOException,
 			RefNotFoundException {
-		RevWalk revWalk = new RevWalk(repo);
 		DirCache dc = repo.lockDirCache();
-		try {
+		try (RevWalk revWalk = new RevWalk(repo);
-			TreeWalk treeWalk = new TreeWalk(revWalk.getObjectReader());
+				TreeWalk treeWalk = new TreeWalk(revWalk.getObjectReader())) {
 			treeWalk.setRecursive(true);
 			if (!checkoutAllPaths)
 				treeWalk.setFilter(PathFilterGroup.createFromStrings(paths));
-			try {
 			if (isCheckoutIndex())
 				checkoutPathsFromIndex(treeWalk, dc);
 			else {
 				RevCommit commit = revWalk.parseCommit(getStartPointObjectId());
 				checkoutPathsFromCommit(treeWalk, dc, commit);
 			}
-			} finally {
-				treeWalk.release();
-			}
 		} finally {
 			dc.unlock();
-			revWalk.release();
 		}
 		return this;
 	}