JGit - Contents of Commit Into String

Question

I need to store the contents of a commit, this would be the difference from eg. master to the latest commit, in a string.

How to show changes between commits with JGit The bottom answer is very similar to what I want

This is the code from the link

RevCommit headCommit = getHeadCommit(repository);
    RevCommit diffWith = headCommit.getParent(0);
    FileOutputStream stdout = new FileOutputStream(FileDescriptor.out);
    try (DiffFormatter diffFormatter = new DiffFormatter(stdout)) {
        diffFormatter.setRepository(repository);
        for (DiffEntry entry : diffFormatter.scan(diffWith, headCommit)) {
            diffFormatter.format(diffFormatter.toFileHeader(entry));
        }
    }

diffFormatter.format(diffFormatter.toFileHeader(entry));

The format() method is void, and there doesnt seem to be a way to return a string or some sort of outputstream.

I would expect there to be something along the lines of

String commitDiff = diffFormatter.getCommitContents(entry).toString();

I understand this doesnt exist in the library, but there must be something that can put the contents of a commit into something that can be turned into a String

Answer 1

The code was changed to

OutputStream output = new OutputStream() {
    private StringBuilder string = new StringBuilder();
    @Override
    public void write(int b) throws IOException {
        this.string.append((char) b );
    }

    public String toString(){
        return this.string.toString();
    }
};
RevCommit headCommit = getHeadCommit(repository);
RevCommit diffWith = headCommit.getParent(0);
try (DiffFormatter diffFormatter = new DiffFormatter(output)) {
    diffFormatter.setRepository(repository);
    for (DiffEntry entry : diffFormatter.scan(diffWith, headCommit)) {
        diffFormatter.format(diffFormatter.toFileHeader(entry));
    }
String strings = output.toString();
System.out.println(strings);

It is a long way of doing it but it proves it can be done This has now stored the difference into the string

strings