How to keep a diary private on Android
Short answer: Lock the diary app itself with a PIN, hide its preview in recent apps, make it lock again when you leave, and keep notifications free of your writing.
Six settings that matter
- An app PIN. Your phone lock does not help when someone borrows your unlocked phone.
- Fingerprint as a shortcut, PIN as the fallback.
- Hide the recent apps preview. Otherwise your last page shows in the app switcher.
- Lock again after leaving. Right away or after a minute.
- No text in notifications or widgets. A reminder should never quote your entry.
- Keep backups somewhere only you can open.
Privacy in Inkleaf
Inkleaf has a 4-digit PIN with optional fingerprint, hides the recent apps preview while locked, locks again right away, after 1 or 5 minutes, and its widget and reminders never show what you wrote. Everything stays on your phone.