Get Commit of a particular SHA-1 in jGit - jgit

Question

I have a SHA-1 of a newly cloned repository. I want the author indent of this SHA-1.
So I need to use RevWalk and iterate the whole repository? Or is there a findXX method or other code I can use to get the RevCommit or another object that has the PersonIdent?
What I tried:
public void authorInfoOf(Repository repo, AnyObjectId head) {
try {
try (RevWalk walk = new RevWalk(repo)) {
ObjectDatabase db = repo.getObjectDatabase();
ObjectLoader k = repo.newObjectReader().open(head);
ObjectReader s;
// repo.newObjectReader().open(head);
ObjectStream st = k.openStream();
// RevWalk rw2 = new RevWalk(k);
RevCommit commit = null;// walk.parseCommit(ref.getObjectId());
PersonIdent authorIndent = commit.getAuthorIdent();
System.out.println("\nCommit-Message: " + commit.getFullMessage() + " " + authorIndent.getEmailAddress());
}
} catch (Exception e) {
System.out.println("Authir info of Anybject id Err " + e);
e.printStackTrace();
}
}

Answer 1

The RevCommit represents a particular commit in a Git repository. Use RevWalk::parseCommit() to obtain the RevCommit for a specific object id/SHA-1.
For example:
try( RevWalk walk = new RevWalk( repository ) ) {
RevCommit commit = walk.parseCommit( ref.getObjectId() );
}
parseCommit returns the matching commit object for the given ObjectId.
In order to convert a SHA-1 (string) into an ObjectId, use ObjectId::fromString():
ObjectId commitId = ObjectId.fromString( "ab434..." );
See also: How to obtain the RevCommit or ObjectId from a SHA1 ID string with JGit?
In the above example, a Ref was used to reference the object id. Refs represent named references to object ids like branches, tags, or special refs like HEAD. Repository::exactRef() can be used to resolve a string to a Ref object.
For example:
Ref headRef = repository.exactRef( "HEAD" );

Answer 2

This worked for me:
public RevCommit getCommit(String idString, Repository repository, Git git){
try{
ObjectId o1 = repository.resolve(idString);
if(o1 != null){
try( RevWalk walk = new RevWalk( repository ) ) {
RevCommit commit = walk.parseCommit( o1 );
PersonIdent ai = commit.getAuthorIdent();
System.out.println("bbb >>" + ai.getEmailAddress() + "|" + ai.getTimeZone() + "|" + ai.getWhen() + ", ref :" + idString);
return commit;
}
}else{
System.err.println("Could not get commit with SHA :" + idString);
}
}catch (Exception e) {
System.out.println("err :" + e);
e.printStackTrace();
}
return null;
}