Program style guide - Objects First with Java: A Practical Introduction Using BlueJ - page 534

J.4.6 Always include a superclass constructor call
In constructors of subclasses, do not rely on automatic insertion of a superclass call. Include the
super() call explicitly, even if it would work without it.

J.4.7 Initialize all fields in the constructor

J.5 Code idioms

J.5.1 Use iterators with collections
To iterate over a complete collection, use a for-each loop. When the collection must be changed
during iteration, use an Iterator with a while loop or a for loop, not an integer index.