AI Did the Grunt Work: Porting an RTF Parser from Android to HarmonyOS

Cross-platform code migration—historically a multi-day slog of language translation, build fixing, and debugging—now fits in an afternoon, provided the output is checked. The AI faithfully carried over the original Android bugs, so human verification remains the unavoidable final step.

HarmonyOS natively supports PDF, TXT, EPUB, MOBI, and AZW3, but not RTF, DjVu, or DOCX. Porting an existing parser from another platform normally means translating C/Java/JavaScript code, fixing build issues, and debugging the result—days of tedious work. This walkthrough shows how AI compressed that into a few hours.

The developer chose RTF because it is a simple, cross-platform ASCII-based format. After asking Doubao for open-source RTF parsers, they landed on LibreraReader, a pure-Java reader using the BSD-licensed RtfParserKit. They then used Trae to strip the RTF-related code out of LibreraReader into a new Android project, fix a bug where images came out as 16-byte files, then convert that entire Android project to a HarmonyOS app in ArkTS. Both conversions took about an hour of AI computation, plus debugging.

Two bugs surfaced: odd alphanumeric strings mixed into text and missing images. Trae traced both to an off-by-one error in readCommand() that had been copied from the Java version. A second test found missing bold/italic and dead hyperlinks, which turned out to be a pre-existing flaw in the original Android code that AI had faithfully ported. AI fixed that too, and the final app renders rich RTF correctly.