How to count inserted/deleted lines in JGit

Question

When we do git log --shortstat we get the number of lines inserted, deleted, and changed. Something like:

1 file changed, 9 insertions(+), 3 deletions(-)

Please help me with getting the number of lines inserted, deleted, and changed.

1. I am doing a repository clone to get git project on local machine. Here is the same code:

    RepoClone repoClone = new RepoClone();
    repoClone.repoCloner();
    repository = builder.setGitDir(repoClone.repoDir).setMustExist(true).build();
   

2. I am even able to get a TreeWalk:

    TreeWalk treeWalk = getCommitsTreeWalk();
   

3. I am able to retrieve file name, count of number of commits per file, LOC, and the number of developers who worked on each xml/ java file.

    while (treeWalk.next()) {
      if (treeWalk.getPathString().endsWith(".xml") || treeWalk.getPathString().endsWith(".java")) {
        jsonDataset = new JSONObject();
        countDevelopers = new HashSet<String>();
        count = 0;
        logs = new Git(repository).log().addPath(treeWalk.getPathString()).call();
        for (RevCommit rev: logs) {
          countDevelopers.add(rev.getAuthorIdent().getEmailAddress());
          count++;
        }
        jsonDataset.put("FileName", treeWalk.getPathString());
        jsonDataset.put("CountDevelopers", countDevelopers.size());
        jsonDataset.put("CountCommits", count);
        jsonDataset.put("LOC", countLines(treeWalk.getPathString()));
        commitDetails.put(jsonDataset);
      }
    }
   

4. Now, I want to retrieve the number of lines inserted and deleted for each file.

Answer 1

The following code snippet compares two commits and prints the changes. diffFormatter.scan() returns a list of DiffEntrys which each describes an added, deleted or modified file. Each of the diff entries in turn has a list of HunkHeaders which desribe the changes within that file.

// Create two commits to be compared
File file = new File( git.getRepository().getWorkTree(), "file.txt" );
writeFile( file, "line1\n" );
RevCommit oldCommit = commitChanges();
writeFile( file, "line1\nline2\n" );
RevCommit newCommit = commitChanges();

// Obtain tree iterators to traverse the tree of the old/new commit
ObjectReader reader = git.getRepository().newObjectReader();
CanonicalTreeParser oldTreeIter = new CanonicalTreeParser();
oldTreeIter.reset( reader, oldCommit.getTree() );
CanonicalTreeParser newTreeIter = new CanonicalTreeParser();
newTreeIter.reset( reader, newCommit.getTree() );

// Use a DiffFormatter to compare new and old tree and return a list of changes
DiffFormatter diffFormatter = new DiffFormatter( DisabledOutputStream.INSTANCE );
diffFormatter.setRepository( git.getRepository() );
diffFormatter.setContext( 0 );
List<DiffEntry> entries = diffFormatter.scan( newTreeIter, oldTreeIter );

// Print the contents of the DiffEntries
for( DiffEntry entry : entries ) {
  System.out.println( entry );
  FileHeader fileHeader = diffFormatter.toFileHeader( entry );
  List<? extends HunkHeader> hunks = fileHeader.getHunks();
  for( HunkHeader hunk : hunks ) {
    System.out.println( hunk );
  }
}

I think with the information provided by DiffEntry and HunkHeader you should be able to get the desired --shortstat.