Best way to start a cross-platform java application?

Question

I want to rewrite a program from c++ win32 api to Java and be able to run it on Android mobile devices, Mac and, windows computers. Where should I start looking.
The application needs access to read txt files for setting up arraylists and audio playback of wav files as well as creating text forms and buttons on screen.

Answer 1

I would start by installing a program such as Eclipse or Android Studio on a computer. There's an app on the Play Store called "Tutorials for Android: Examples" (link below) that serves as a good reference point for developing apps, and includes an example of using buttons. Hope this helps.

https://play.google.com/store/apps/details?id=arjuntoshniwal.androidtutorials.advanced&hl=en&referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dtutorials+for+android:examples&pcampaignid=APPU_1_afx5Wb_mCcrR0gLjy5mYCw