This code can be used to add comments in Word file using Java. More details are available here: https://kb.aspose.com/words/java/how-to-add-comments-in-word-using-java/

How to Add Comments in Word using Java.java

import com.aspose.words.License;

import com.aspose.words.Document;
import com.aspose.words.DocumentBuilder;
import com.aspose.words.Comment;
import com.aspose.words.Paragraph;
import com.aspose.words.Run;
import java.util.Date;

public class HowToAddCommentsInWordUsingJava
{
    public static void main(String[] args) throws Exception { //main function for AddImageInWord class

    	// Initialize a license to avoid trial version watermark in the output Word file after adding image
    	License license = new License(); 
    	license.setLicense("Aspose.Words.lic");

    	// Load the Word document where comments are to be added 
    	Document DocumentForComment = new Document("input.docx");
    	DocumentBuilder builder = new DocumentBuilder(DocumentForComment);

    	// Move the cursor to the beginning of the document for adding comments 
    	builder.moveToDocumentStart();
    
    	// Insert comment to first paragraph of document by providing Author, Initial, time and comment text
    	Comment comment = new Comment(DocumentForComment, "Aspose.Words", "AW", new Date());
    	builder.getCurrentParagraph().appendChild(comment);
    	comment.getParagraphs().add(new Paragraph(DocumentForComment));
    	comment.getFirstParagraph().getRuns().add(new Run(DocumentForComment, "Comment text."));

    	// Save the Document with comments
    	DocumentForComment.save("OutputDocumentWithComments.docx");
    }
}