answer 9)

3 ) 2

no error will be triggered.

like in c/c++, arrays are always referenced from 0. java allows an array to be populated at creation time. the size of array is taken from the number of initializers. if you put a size within any of the square brackets you will get an error.

answer 10)

3) 0

arrays are always initialised when they are created. as this is an array of ints it will be initalised with zeros.

answer 11)

3) error mine must be declared abstract
 

a class that contains an abstract method must itself be declared as abstract. it may however contain non abstract methods. any class derived from an abstract class must either define all of the abstract methods or be declared abstract itself.

answer 12)

3) one, two, default

code will continue to fall through a case statement until it encounters a break.

answer 13)

2) default, zero

although it is normally placed last the default statement does not have to be the last item as you fall through the case block. because there is no case label found matching the expression the default label is executed and the code continues to fall through until it encounters a break.

answer 14)

2,3

example 1 will not compile because if must always test a boolean. this can catch out c/c++ programmers who expect the test to be for either 0 or not 0.