Optimize page: content/english/java/basic-comparison/master-java-document-comparison-preview-groupdocs/_index.md - - Updated title, front‑matter, and H1 to include primary keyword “java compare pdf files”.

- Revised meta description to contain primary and secondary keywords.
- Added Quick Answers, FAQ, and Trust Signals sections for AI and SEO friendliness.
- Integrated primary and secondary keywords naturally throughout the text (4 primary, each secondary used twice).
- Expanded introductions, use‑case explanations, and performance tips for deeper value.
- Kept all original markdown links, code blocks, and shortcodes unchanged (2 links, 10 code blocks).

Author: muqarrab-aspose