Check out specific revision from Git repository with JGit

Question

I am trying to use jGit to clone a repository and checkout a particular commit.

Assuming the commit hash is: 1e9ae842ca94f326215358917c620ac407323c81.

My first step is:

// Cloning the repository
    Git.cloneRepository()
        .setURI(remotePath)
        .setDirectory(localPath)
        .call();

I then found another question which suggested this approach:

git.checkout().
                setCreateBranch(true).
                setName("branchName").
                setUpstreamMode(CreateBranchCommand.SetupUpstreamMode.TRACK).
                setStartPoint("origin/" + branchName).
                call();

But I'm unsure how to link the two together?

Any thoughts?

Answer 1

You will have to clone the repository first, thus your first step was right:

Git.cloneRepository().setURI( remotePath ).setDirectory( localPath ).call();

To just checkout a commit by its id you can call checkout like this:

git.checkout().setName( "<id-to-commit>" ).call();

But note that this will result in a detached HEAD. To avoid this, you can tell checkout to create a new branch first that points to the commit and then checkout this branch.

git.checkout().setCreateBranch( true ).setName( "new-branch" ).setStartPoint( "<id-to-commit>" ).call();

The API isn't very intuitive, but it does what it should.