Android tricks

This post will gather all those little tricks that speed up your Android development, because I found I often get stuck because of poor documentation.

PopupMenu:

• supply x and y, otherwise it won’t show up

• set a background drawable, or it won’t react to touch events

• You need a style with two items for animation to work http://stackoverflow.com/a/7550227/315306

SQLite

• Primary key must be defined INTEGER PRIMARY KEY NOT NULL (WTF? Not null?) And be careful that if you use INT instead of INTEGER, you won’t have the autoincrement behavior

• Primary key must be explicitly enabled with PRAGMA foreign_keys = ON; (doc). Usually this is done inside onOpen(SQLiteDatabase), after checking that the database is writeable

• Use the class DatabaseUtils

ViewAnimator

• Batch removing children is tricky. First, you must post() to the animator’s Handler. Then you need to set in and out animations to null. Finally, removeViews(int start, int count) doesn’t work well, so you have to remove one child at a time, either with removeView(View view) or removeChildAt(int index)

EditText

• getText() returns a CharSequence. It never returns null,  so you must check its length to tell if it’s empty.