5

pre review checklist

Sebastian edited this page 2022-06-29 11:47:34 +00:00

Table of Contents

• Java
• Thread safety
• Visibility
• Constructors and Dependencies
• Exceptions
• Blocking
• Locks
• Android UI
• Icon Drawables

Java

Thread safety

• Classes should be immutable where possible
• Classes that may be used by multiple threads must be thread-safe
• If a class is not thread-safe, annotate it @NotThreadSafe
• Fields that are used by multiple threads must be volatile or guarded by locks
• If a field or method is guarded by a lock, add a comment, e.g. // Locking: foo

Visibility

• Minimise the visibility of classes, fields and methods
• Fields should usually be private, with getters and setters if needed
• Fields should be final where possible
• Inner classes should be static where possible

Constructors and Dependencies

• Never allow this to escape the constructor
• Complex dependencies should be injected or constructed by factories
• Avoid static methods, except for simple and ubiquitous tasks
• Use executors rather than creating threads where possible

Exceptions

• Use checked exceptions rather than special return values to indicate errors
• Unchecked exceptions should only be used for programming errors
• If you catch an InterruptedException in a synchronous method, interrupt the current thread so the caller learns about the interrupt
• RuntimeExceptions thrown by our own code are expected to crash the app, and RuntimeExceptions thrown by libraries should either be caught immediately or allowed to escape and crash the app - but shouldn't be allowed to propagate through layers of our own code before being caught.

Blocking

• Don't call blocking methods from the UI thread
• Don't call blocking methods from event handlers

Locks

• Avoid using locks where possible
• Use dedicated lock objects rather than synchronized
• Don't call into other classes while holding locks
• Don't start database transactions while holding locks

Android UI

Icon Drawables

• Use app:srcCompat instead of android:src to define drawables in XML files
• Use setImageResource() to set icons instead of setImageDrawable()
• If you need to set a drawable directly, but can't use setImageResource(), use VectorDrawableCompat.create() to get the drawable
• Don't use vector(-only) drawables for notification icons (unless that's supported now)
• Test icon display on API < 21