Add snippet that shows how to use all available tags/branches/remotes…

…/HEADs to list information about all commits in the repository

README.md

@@ -98,6 +98,7 @@ Please make sure to take a look at the nicely written [introduction](http://www.
 * [List files in a directory as-of a specific commit or a tag](https://github.com/centic9/jgit-cookbook/blob/master/src/main/java/org/dstadler/jgit/api/ListFilesOfCommitAndTag.java)
 * [Iterate over files of a commit recursively](https://github.com/centic9/jgit-cookbook/blob/master/src/main/java/org/dstadler/jgit/api/WalkTreeRecursive.java)
 * [Iterate over files of a commit non-recursively](https://github.com/centic9/jgit-cookbook/blob/master/src/main/java/org/dstadler/jgit/api/WalkTreeNonRecursive.java)
+* [Find all commits that are reachable via tags, branches, remotes, HEADs, ...](https://github.com/centic9/jgit-cookbook/blob/master/src/main/java/org/dstadler/jgit/api/WalkAllCommits.java)
 
 ##### GitServlet
 

src/main/java/org/dstadler/jgit/api/WalkAllCommits.java

@@ -0,0 +1,57 @@
+package org.dstadler.jgit.api;
+
+/*
+   Copyright 2016 Dominik Stadler
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+ */
+
+import org.dstadler.jgit.helper.CookbookHelper;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+import java.io.IOException;
+import java.util.Collection;
+
+
+/**
+ * Simple snippet which shows how to use RevWalk to iterate over all commits
+ * across all branches/tags/remotes in the given repository
+ *
+ * See the original discussion at http://stackoverflow.com/a/40803945/411846
+ */
+public class WalkAllCommits {
+
+    public static void main(String[] args) throws IOException {
+        try (Repository repository = CookbookHelper.openJGitCookbookRepository()) {
+            // get a list of all known heads, tags, remotes, ...
+            Collection<Ref> allRefs = repository.getAllRefs().values();
+
+            // a RevWalk allows to walk over commits based on some filtering that is defined
+            try (RevWalk revWalk = new RevWalk( repository )) {
+                for( Ref ref : allRefs ) {
+                    revWalk.markStart( revWalk.parseCommit( ref.getObjectId() ));
+                }
+                System.out.println("Walking all commits starting with " + allRefs.size() + " refs: " + allRefs);
+                int count = 0;
+                for( RevCommit commit : revWalk ) {
+                    System.out.println("Commit: " + commit);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits");
+            }
+        }
+    }
+}

src/test/java/org/dstadler/jgit/api/ApiTest.java

@@ -29,6 +29,7 @@ public void runSamples() throws Exception {
         ReadUserConfig.main(null);
         ResolveRef.main(null);
         ShowBranchTrackingStatus.main(null);
+        WalkAllCommits.main(null);
         WalkRev.main(null);
         WalkFromToRev.main(null);
         WalkTreeNonRecursive.main(null);