Using JGIT, how can I get line numbers of added / deleted lines

Question

Assuming the following code snippet is bound to a Git repository:

int test(){ int a = 3; int b = 4; int c = a + b; return c; } 

and later updated to

 int test(){ return 7; } 

I currently have a method that uses the JGit API to access the Git repository, as indicated above, and outputs a line that looks like the following:

 int test(){ -int a = 3; -int b = 4; -int c = a + b; -return c; +return 7; } 

Now my requirements have changed and would like to know the line numbers of only the changed lines. So I would like something like the following:

 2 -int a = 3; 3 -int b = 4; 4 -int c = a + b; 5 -return c; 2 +return 7; 

Basically, the same information as the GitHub application when creating the update.

Any help would be greatly appreciated :)

fragment of how strings are calculated - / +:

  String oldHash = "ee3e216ab5047748a22e9ec5ad3e92834704f0cc"; Git git = null; try { //the path where the repo is. git = Git.open(new File("C:\\Users\\Administrator\\Documents\\GitHub\\Trial")); } catch (IOException e1) { e1.printStackTrace(); } Repository repository = git.getRepository(); ObjectId old = null; ObjectId head = null; //a new reader to read objects from getObjectDatabase() ObjectReader reader = repository.newObjectReader(); //Create a new parser. CanonicalTreeParser oldTreeIter = new CanonicalTreeParser(); CanonicalTreeParser newTreeIter = new CanonicalTreeParser(); List<DiffEntry> diffs = null; try { //parse a git repository string and return an ObjectId old = repository.resolve(oldHash + "^{tree}"); head = repository.resolve("HEAD^{tree}"); //Reset this parser to walk through the given tree oldTreeIter.reset(reader, old); newTreeIter.reset(reader, head); diffs = git.diff()//Returns a command object to execute a diff command .setNewTree(newTreeIter) .setOldTree(oldTreeIter) .call();//returns a DiffEntry for each path which is different } catch (RevisionSyntaxException | IOException | GitAPIException e) { // TODO Auto-generated catch block e.printStackTrace(); } //DiffLineCountFilter d = new DiffLineCountFilter(); //out is the stream the formatter will write to ByteArrayOutputStream out = new ByteArrayOutputStream(); //Create a new formatter with a default level of context. DiffFormatter df = new DiffFormatter(out); //Set the repository the formatter can load object contents from. df.setRepository(git.getRepository()); ArrayList<String> diffText = new ArrayList<String>(); //A DiffEntry is 'A value class representing a change to a file' therefore for each file you have a diff entry for(DiffEntry diff : diffs) { try { //Format a patch script for one file entry. df.format(diff); RawText r = new RawText(out.toByteArray()); r.getLineDelimiter(); diffText.add(out.toString()); out.reset(); } catch (IOException e) { e.printStackTrace(); } } 

Answer 1

Just a hint for those who may have this problem. I was not able to get the line numbers of the added and deleted lines, but I was able to get a line containing only the added and deleted lines, without other lines that were not changed.

This was simply done by adding a line:

  df.setContext(0); 

in the above snippet right before the line

  df.format(diff); 

Answer 2

You need to make the difference between the indices of row A and the indices of row B from the diff result:

 int linesAdded = 0; int linesDeleted = 0; int filesChanged = 0; try { repo = new FileRepository(new File("repo/.git")); RevWalk rw = new RevWalk(repo); RevCommit commit = rw.parseCommit(repo.resolve("486817d67b")); // Any ref will work here (HEAD, a sha1, tag, branch) RevCommit parent = rw.parseCommit(commit.getParent(0).getId()); DiffFormatter df = new DiffFormatter(DisabledOutputStream.INSTANCE); df.setRepository(repo); df.setDiffComparator(RawTextComparator.DEFAULT); df.setDetectRenames(true); List<DiffEntry> diffs; diffs = df.scan(parent.getTree(), commit.getTree()); filesChanged = diffs.size(); for (DiffEntry diff : diffs) { for (Edit edit : df.toFileHeader(diff).toEditList()) { linesDeleted += edit.getEndA() - edit.getBeginA(); linesAdded += edit.getEndB() - edit.getBeginB(); } } } catch (IOException e1) { throw new RuntimeException(e1); }