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How to Use GIT Java APIs to Diff Two Different Files

February 11th, 2013 Leave a comment Go to comments

In my previous post, I introduced a sample showing how to use JGIT Java APIs to diff two versions of a same file in repository. The JGIT Java APIs can do more than that – it can actually diff two text files that are not even controlled by GIT.
Here is a short sample code on how to do this. Again, it’s not the main use case for the JGIT APIs. After all, it’s mainly for GIT source control system itself. You can always use other diff APIs for this purpose. However, if you already have JGIT included, this can be handy.

/**Copyright Steve Jin 2013 */
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;

import org.eclipse.jgit.diff.DiffFormatter;
import org.eclipse.jgit.diff.EditList;
import org.eclipse.jgit.diff.HistogramDiff;
import org.eclipse.jgit.diff.RawText;
import org.eclipse.jgit.diff.RawTextComparator;

public class RawDiff
  public static void main(String[] args) throws Exception
    ByteArrayOutputStream out = new ByteArrayOutputStream();
      RawText rt1 = new RawText(new File("C:\\temp\\twofiles\\file1.txt"));
      RawText rt2 = new RawText(new File("C:\\temp\\twofiles\\file2.txt"));
      EditList diffList = new EditList();
      diffList.addAll(new HistogramDiff().diff(RawTextComparator.DEFAULT, rt1, rt2));
      new DiffFormatter(out).format(diffList, rt1, rt2);
    } catch (IOException e)

The output of the program is like this:

Time to learn how to "Google" and manage your VMware and clouds in a fast and secure

@@ -1,3 +1,4 @@
 This is doublecloud.org
 it just rocks!
 what an interesting work
\ No newline at end of file

Categories: Software Development Tags: ,
  1. lilo
    July 11th, 2013 at 10:11 | #1

    Thanks a lot guy! 😀

    Really needed this.

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