Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 168

The answers to the chapter review questions can be found in the Appendix.

1 Which of the following Java operators can be used with boolean variables? (Choose all that apply.)==+--!%~Cast with (boolean)

2 What data type (or types) will allow the following code snippet to compile? (Choose all that apply.)byte apples = 5; short oranges = 10; _____ bananas = apples + oranges;intlongbooleandoubleshortbyte

3 What change, when applied independently, would allow the following code snippet to compile? (Choose all that apply.)3: long ear = 10; 4: int hearing = 2 * ear;No change; it compiles as is.Cast ear on line 4 to int.Change the data type of ear on line 3 to short.Cast 2 * ear on line 4 to int.Change the data type of hearing on line 4 to short.Change the data type of hearing on line 4 to long.

4 What is the output of the following code snippet?3: boolean canine = true, wolf = true; 4: int teeth = 20; 5: canine = (teeth != 10) ^ (wolf=false); 6: System.out.println(canine+", "+teeth+", "+wolf);true, 20, truetrue, 20, falsefalse, 10, truefalse, 20, falseThe code will not compile because of line 5.None of the above.

5 Which of the following operators are ranked in increasing or the same order of precedence? Assume the + operator is binary addition, not the unary form. (Choose all that apply.)+, *, %, --++, (int), *=, ==, !(short), =, !, **, /, %, +, ==!, ||, &^, +, =, +=

6 What is the output of the following program?1: public class CandyCounter { 2: static long addCandy(double fruit, float vegetables) { 3: return (int)fruit+vegetables; 4: } 5: 6: public static void main(String[] args) { 7: System.out.print(addCandy(1.4, 2.4f) + ", "); 8: System.out.print(addCandy(1.9, (float)4) + ", "); 9: System.out.print(addCandy((long)(int)(short)2, (float)4)); } }4, 6, 6.03, 5, 63, 6, 64, 5, 6The code does not compile because of line 9.None of the above.

7 What is the output of the following code snippet?int ph = 7, vis = 2; boolean clear = vis> 1 & (vis < 9 || ph < 2); boolean safe = (vis> 2) && (ph++> 1); boolean tasty = 7 <= --ph; System.out.println(clear + "-" + safe + "-" + tasty);true-true-truetrue-true-falsetrue-false-truetrue-false-falsefalse-true-truefalse-true-falsefalse-false-truefalse-false-false

8 What is the output of the following code snippet?4: int pig = (short)4; 5: pig = pig++; 6: long goat = (int)2; 7: goat -= 1.0; 8: System.out.print(pig + " - " + goat);4 - 14 - 25 - 15 - 2The code does not compile due to line 7.None of the above.

9 What are the unique outputs of the following code snippet? (Choose all that apply.)int a = 2, b = 4, c = 2; System.out.println(a> 2 ? --c : b++); System.out.println(b = (a!=c ? a : b++)); System.out.println(a> b ? b < c ? b : 2 : 1);123456The code does not compile.

10 What are the unique outputs of the following code snippet? (Choose all that apply.)short height = 1, weight = 3; short zebra = (byte) weight * (byte) height; double ox = 1 + height * 2 + weight; long giraffe = 1 + 9 % height + 1; System.out.println(zebra); System.out.println(ox); System.out.println(giraffe);123456The code does not compile.

11 What is the output of the following code?11: int sample1 = (2 * 4) % 3; 12: int sample2 = 3 * 2 % 3; 13: int sample3 = 5 * (1 % 2); 14: System.out.println(sample1 + ", " + sample2 + ", " + sample3);0, 0, 51, 2, 102, 1, 52, 0, 53, 1, 103, 2, 6The code does not compile.

12 The _________ operator increases a value and returns the original value, while the _______ operator decreases a value and returns the new value.post-increment, post-incrementpre-decrement, post-decrementpost-increment, post-decrementpost-increment, pre-decrementpre-increment, pre-decrementpre-increment, post-decrement

13 What is the output of the following code snippet?boolean sunny = true, raining = false, sunday = true; boolean goingToTheStore = sunny & raining ^ sunday; boolean goingToTheZoo = sunday && !raining; boolean stayingHome = !(goingToTheStore && goingToTheZoo); System.out.println(goingToTheStore + "-" + goingToTheZoo + "-" +stayingHome);true-false-falsefalse-true-falsetrue-true-truefalse-true-truefalse-false-falsetrue-true-falseNone of the above

14 Which of the following statements are correct? (Choose all that apply.)The return value of an assignment operation expression can be void.The inequality operator (!=) can be used to compare objects.The equality operator (==) can be used to compare a boolean value with a numeric value.During runtime, the & and | operators may cause only the left side of the expression to be evaluated.The return value of an assignment operation expression is the value of the newly assigned variable.In Java, 0 and false may be used interchangeably.The logical complement operator (!) cannot be used to flip numeric values.

15 Which operators take three operands or values? (Choose all that apply.)=&&*=? :&++/

16 How many lines of the following code contain compiler errors?int note = 1 * 2 + (long)3; short melody = (byte)(double)(note *= 2); double song = melody; float symphony = (float)((song == 1_000f) ? song * 2L : song);01234

17 Given the following code snippet, what are the values of the variables after it is executed? (Choose all that apply.)int ticketsTaken = 1; int ticketsSold = 3; ticketsSold += 1 + ticketsTaken++; ticketsTaken *= 2; ticketsSold += (long)1;ticketsSold is 8.ticketsTaken is 2.ticketsSold is 6.ticketsTaken is 6.ticketsSold is 7.ticketsTaken is 4.The code does not compile.

18 Which of the following can be used to change the order of operation in an expression? (Choose all that apply.)[ ]< >( )\ /{ }" "

19 What is the result of executing the following code snippet? (Choose all that apply.)3: int start = 7; 4: int end = 4; 5: end += ++start; 6: start = (byte)(Byte.MAX_VALUE + 1);start is 0.start is -128.start is 127.end is 8.end is 11.end is 12.The code does not compile.The code compiles but throws an exception at runtime.

20 Which of the following statements about unary operators are true? (Choose all that apply.)Unary operators are always executed before any surrounding numeric binary or ternary operators.The - operator can be used to flip a boolean value.The pre-increment operator (++) returns the value of the variable before the increment is applied.The post-decrement operator (--) returns the value of the variable before the decrement is applied.The ! operator cannot be used on numeric values.None of the above

21 What is the result of executing the following code snippet?int myFavoriteNumber = 8; int bird = ~myFavoriteNumber; int plane = -myFavoriteNumber; var superman = bird == plane ? 5 : 10; System.out.println(bird + "," + plane + "," + --superman);-7,-8,9-7,-8,10-8,-8,4-8,-8,5-9,-8,9-9,-8,10None of the above