Exercises 2.2

For Exercises 1-16, determine if each is a valid Java identifier. If it is not, give a reason.

1. XRay valid

2. X-Ray invalid; - is not a legal character in an identifier

3. Jeremiah valid

4. R2_D2 valid

5. 3M invalid; identifiers cannot begin with a number

6. PDQ123 valid

7. PS.175 invalid; . is not a legal character in an identifier

8. x valid

9. 4 invalid; identifiers cannot begin with a number

10. N/4 invalid; / is not a legal character in an identifier

11. M&M invalid; $ is not a legal character in an identifier

12. Z_Z_Z_Z_Z_Z valid

13. night valid

14. ngiht valid

15. nite valid

16. to day invalid; identifiers cannot contain spaces

For Exercises 17-21, write declarations for each variable.

17. double item, number, job;

18. int shoeSize;

19. double mileage;

short cost, distance;

20. long alpha, beta;

double root;

21. String name;

isAStudent boolean;

22-26. For each variable in Exercises 17-21, tell what default value will be used to initialize it.

22. double item, number, job; -- all will be initialized to zero

23. int shoeSize; -- will be initialized to zero

24. double mileage; -- will be initialized to zero

short cost, distance; -- will be initialized to zero

25. long alpha, beta; -- will be initialized to zero

double root; -- will be initialized to zero

26. String name; -- will be initialized to null

isAStudent boolean; -- -- will be initialized to false

For Exercises 27-28, write declarations for each variable so that it has the specified type and initial value.

27.

int numberOfDeposits = 0,

numberOfChecks = 0;

double totalDeposits = 0.0,

totalChecks = 0.0,

serviceCharge = 0.25;

28.

char symbol_1 = ' ' , symbol_2 = ';' ;

boolean debug = true;

For Exercises 29-32, write constant declarations to associate each name with the specified literal:

29. const double RATE = 1.25;

30. const double REGULAR_HOURS = 40.0, OVERTIME_FACTOR = 1.5;

31. const int YEAR = 1776;

const char FEMALE = 'F',

BLANK = ' ';

32. const int ZERO = 0;

const char ASTERISK = '*',

APOSTROPHE = '\'';

33. const int YEAR = 2001;

const double MAXIMUM_SALARY = 99999.99;

int prime, number;

char initial;