Type Inference‘s Best Practice

Programming Best Practices

When to have type inference?

Better not annotate the type of a private field or a local variable as their type will usually be immediately evident in their value.

When to avoid type inference?

Better to display the type where the assigned value has a complex or non-obvious form.

All public methods should have explicit type annotations — without an explicit type, a change to the internals of a method or val could alter the public API of the class without warning, potentially breaking client code.