two

Question 1

Which of the following Java operators can be used with boolean variables? (Choose all that 
apply)
A.  ==
B.  +
C.  --
D.  !
E.  %
F.  <=

Answer 1

A, D. Option A is the equality operator and can be used on numeric primitives, bool-ean values, and object references. Options B and C are both arithmetic operators and
cannot be applied to a boolean value. Option D is the logical complement operator
and is used exclusively with boolean values. Option E is the modulus operator, which
can only be used with numeric primitives. Finally, option F is a relational operator that
compares the values of two numbers.

Question 2

What data type (or types) will allow the following code snippet to compile? (Choose all that 
apply)
byte x = 5;
byte y = 10;
\_\_\_\_\_ z = x + y;
A.  int
B.  long
C.  boolean
D.  double
E.  short
F.  byte

Answer 2

A, B, D. The value x + y is automatically promoted to int, so int and data types that
can be promoted automatically from int will work. Options A, B, D are such data
types. Option C will not work because boolean is not a numeric data type. Options E
and F will not work without an explicit cast to a smaller data type.

Question 3

What is the output of the following application?
1: public class CompareValues {
2: public static void main(String[] args) {
3: int x = 0;
4: while(x++ < 10) {}
5: String message = x > 10 ? “Greater than” : false;
6: System.out.println(message+”,”+x);
7: }
8: }
A. Greater than,10
B. false,10
C. Greater than,11
D. false,11
E. The code will not compile because of line 4.
F. The code will not compile because of line 5.

Answer 3

F. In this example, the ternary operator has two expressions, one of them a String and
the other a boolean value. The ternary operator is permitted to have expressions that
don’t have matching types, but the key here is the assignment to the String reference.
The compiler knows how to assign the first expression value as a String, but the sec-ond boolean expression cannot be set as a String; therefore, this line will not compile.

Question 4

What change would allow the following code snippet to compile? (Choose all that apply)
3: long x = 10;
4: int y = 2 * x;
A. No change; it compiles as is.
B. Cast x on line 4 to int.
C. Change the data type of x on line 3 to short.
D. Cast 2 * x on line 4 to int.
E. Change the data type of y on line 4 to short.
F. Change the data type of y on line 4 to long.

Answer 4

B, C, D, F. The code will not compile as is, so option A is not correct. The value 2 * x
is automatically promoted to long and cannot be automatically stored in y, which is
in an int value. Options B, C, and D solve this problem by reducing the long value to
int. Option E does not solve the problem and actually makes it worse by attempting
to place the value in a smaller data type. Option F solves the problem by increasing the
data type of the assignment so that long is allowed.

Question 5

What is the output of the following code snippet?
3: java.util.List list = new java.util.ArrayList();
4: list.add(10);
5: list.add(14);
6: for(int x : list) {
7: System.out.print(x + “, “);
8: break;
9: }
A. 10, 14,
B. 10, 14
C. 10,
D. The code will not compile because of line 7.
E. The code will not compile because of line 8.
F. The code contains an infinite loop and does not terminate.

Answer 5

C. This code does not contain any compilation errors or an infinite loop, so options D,
E, and F are incorrect. The break statement on line 8 causes the loop to execute once
and finish, so option C is the correct answer.

Question 6

What is the output of the following code snippet?
3: int x = 4;
4: long y = x * 4 - x++;
5: if(y<10) System.out.println(“Too Low”);
6: else System.out.println(“Just right”);
7: else System.out.println(“Too High”);
A. Too Low
B. Just Right
C. Too High
D. Compiles but throws a NullPointerException.
E. The code will not compile because of line 6.
F. The code will not compile because of line 7.

Answer 6

F. The code does not compile because two else statements cannot be chained together
without additional if-then statements, so the correct answer is option F. Option E is
incorrect as Line 6 by itself does not cause a problem, only when it is paired with Line
7. One way to fix this code so it compiles would be to add an if-then statement on
line 6. The other solution would be to remove line 7.

Question 7

What is the output of the following code?
1: public class TernaryTester {
2: public static void main(String[] args) {
3: int x = 5;
4: System.out.println(x > 2 ? x < 4 ? 10 : 8 : 7);
5: }}
A. 5
B. 4
C. 10
D. 8
E. 7
F. The code will not compile because of line 4.

Answer 7

D. As you learned in the section “Ternary Operator,” although parentheses are not
required, they do greatly increase code readability, such as the following equivalent
statement:
System.out.println((x > 2) ? ((x < 4) ? 10 : 8) : 7)
We apply the outside ternary operator f rst, as it is possible the inner ternary expression
may never be evaluated. Since (x>2) is true, this reduces the problem to:
System.out.println((x < 4) ? 10 : 8)
Since x is greater than 2, the answer is 8, or option D in this case.

Question 8

What is the output of the following code snippet?
3: boolean x = true, z = true;
4: int y = 20;
5: x = (y != 10) ^ (z=false);
6: System.out.println(x+", "+y+", "+z);
A.  true, 10, true
B.  true, 20, false
C.  false, 20, true
D.  false, 20, false
E.  false, 20, true
F.  The code will not compile because of line 5.

Answer 8

B. This example is tricky because of the second assignment operator embedded in line
5. The expression (z=false) assigns the value false to z and returns false for the
entire expression. Since y does not equal 10, the left-hand side returns true; therefore,
the exclusive or (^) of the entire expression assigned to x is true. The output reflects
these assignments, with no change to y, so option B is the only correct answer. The
code compiles and runs without issue, so option F is not correct.

Question 9

How many times will the following code print “Hello World”?
3: for(int i=0; i<10 ; ) {
4: i = i++;
5: System.out.println(“Hello World”);
6: }
A. 9
B. 10
C. 11
D. The code will not compile because of line 3.
E. The code will not compile because of line 5.
F. The code contains an infinite loop and does not terminate.

Answer 9

F. In this example, the update statement of the for loop is missing, which is fine as the
statement is optional, so option D is incorrect. The expression inside the loop incre-ments i but then assigns i the old value. Therefore, i ends the loop with the same value that it starts with: 0. The loop will repeat infinitely, outputting the same statement over
and over again because i remains 0 after every iteration of the loop.

Question 10

What is the output of the following code?

3: byte a = 40, b = 50;
4: byte sum = (byte) a + b;
5: System.out.println(sum);

A.  40
B.  50
C.  90
D.  The code will not compile because of line 4.
E.  An undefined value.

Answer 10

D. Line 4 generates a possible loss of precision compiler error. The cast operator has
the highest precedence, so it is evaluated first, casting a to a byte. Then, the addition is
evaluated, causing both a and b to be promoted to int values. The value 90 is an int
and cannot be assigned to the byte sum without an explicit cast, so the code does not
compile. The code could be corrected with parentheses around (a + b), in which case
option C would be the correct answer.

Question 11

What is the output of the following code?
1: public class ArithmeticSample {
2: public static void main(String[] args) {
3: int x = 5 * 4 % 3;
4: System.out.println(x);
5: }}
A. 2
B. 3
C. 5
D. 6
E. The code will not compile because of line.

Answer 11

A. The * and % have the same operator precedence, so the expression is evaluated
from left-to-right. The result of 5 * 4 is 20, and 20 % 3 is 2 (20 divided by 3 is 18, the
remainder is 2). The output is 2 and option A is the correct answer.

Question 12

What is the output of the following code snippet?
3: int x = 0;
4: String s = null;
5: if(x == s) System.out.println(“Success”);
6: else System.out.println(“Failure”);
A. Success
B. Failure
C. The code will not compile because of line 4.
D. The code will not compile because of line 5.

Answer 12

D. The variable x is an int and s is a reference to a String object. The two data types
are incomparable because neither variable can be converted to the other variable’s type.
The compiler error occurs on line 5 when the comparison is attempted, so the answer
is option D.

Question 13

What is the output of the following code snippet?
3: int x1 = 50, x2 = 75;
4: boolean b = x1 >= x2;
5: if(b = true) System.out.println(“Success”);
6: else System.out.println(“Failure”);
A. Success
B. Failure
C. The code will not compile because of line 4.
D. The code will not compile because of line 5.

Answer 13

A. The code compiles successfully, so options C and D are incorrect. The value of b
after line 4 is false. However, the if-then statement on line 5 contains an assignment,
not a comparison. The variable b is assigned true on line 3, and the assignment opera-tor returns true, so line 5 executes and displays Success, so the answer is option A.

Question 14

What is the output of the following code snippet?
3: int c = 7;
4: int result = 4;
5: result += ++c;
6: System.out.println(result);
A.  8
B.  11
C.  12
D.  15
E.  16
F.  The code will not compile because of line 5.

Answer 14

C. The code compiles successfully, so option F is incorrect. On line 5, the pre-incre-ment operator is used, so c is incremented to 4 and the new value is returned to the
expression. The value of result is computed by adding 4 to the original value of 8,
resulting in a new value of 12, which is output on line 6. Therefore, option C is the
correct answer.

Question 15

What is the output of the following code snippet?
3: int x = 1, y = 15;
4: while x < 10
5: y––;
6: x++;
7: System.out.println(x+”, “+y);
A. 10, 5
B. 10, 6
C. 11, 5
D. The code will not compile because of line 3.
E. The code will not compile because of line 4.
F. The code contains an infinite loop and does not terminate.

Answer 15

E. This is actually a much simpler problem than it appears to be. The while statement
on line 4 is missing parentheses, so the code will not compile, and option E is the cor-rect answer. If the parentheses were added, though, option F would be the correct
answer since the loop does not use curly braces to include x++ and the boolean expres-sion never changes. Finally, if curly braces were added around both expressions, the
output would be 10, 6 and option B would be correct.

Question 16

What is the output of the following code snippet?
3: do {
4: int y = 1;
5: System.out.print(y++ + “ “);
6: } while(y <= 10);
A. 1 2 3 4 5 6 7 8 9
B. 1 2 3 4 5 6 7 8 9 10
C. 1 2 3 4 5 6 7 8 9 10 11
D. The code will not compile because of line 6.
E. The code contains an infinite loop and does not terminate.

Answer 16

D. The variable y is declared within the body of the do-while statement, so it is out of
scope on line 6. Line 6 generates a compiler error, so option D is the correct answer.

Question 17

What is the output of the following code snippet?
3: boolean keepGoing = true;
4: int result = 15, i = 10;
5: do {
6:   i--;
7:   if(i==8) keepGoing = false;
8:   result -= 2;
9: } while(keepGoing);
10: System.out.println(result);
A.  7
B.  9
C.  10
D.  11
E.  15
F.  The code will not compile because of line 8.

Answer 17

D. The code compiles without issue, so option F is incorrect. After the first execu-tion of the loop, i is decremented to 9 and result to 13. Since i is not 8, keepGoing is
false, and the loop continues. On the next iteration, i is decremented to 8 and result
to 11. On the second execution, i does equal 8, so keepGoing is set to false. At the
conclusion of the loop, the loop terminates since keepGoing is no longer true. The
value of result is 11, and the correct answer is option D.

Question 18

What is the output of the following code snippet?
3: int count = 0;
4: ROW_LOOP: for(int row = 1; row <=3; row++)
5: for(int col = 1; col <=2 ; col++) {
6: if(row * col % 2 == 0) continue ROW_LOOP;
7: count++;
8: }
9: System.out.println(count);
A. 1
B. 2
C. 3
D. 4
E. 6
F. The code will not compile because of line 6.

Answer 18

A. The expression on line 5 is true when row * col is an even number. On the first
iteration, row = 1 and col = 1, so the expression on line 6 is false, the continue is
skipped, and count is incremented to 1. On the second iteration, row = 1 and col = 2, so the expression on line 6 is true and the continue ends the outer loop with
count still at 1. On the third iteration, row = 2 and col = 1, so the expression on line
6 is true and the continue ends the outer loop with count still at 1. On the fourth
iteration, row = 3 and col = 1, so the expression on line 6 is false, the continue is
skipped, and count is incremented to 2. Finally, on the fifth and final iteration, row
= 3 and col = 2, so the expression on line 6 is true and the continue ends the outer
loop with count still at 2. The result of 2 is displayed, so the answer is option B.

Question 19

What is the result of the following code snippet?
3: int m = 9, n = 1, x = 0;
4: while(m > n) {
5:   m--;
6:   n += 2;
7:   x += m + n;
8: }
9: System.out.println(x);
A.  11
B.  13
C.  23
D.  36
E.  50
F.  The code will not compile because of line 7.

Answer 19

D. Prior to the first iteration, m = 9, n = 1, and x = 0. After the iteration of the first
loop, m is updated to 8, n to 3, and x to the sum of the new values for m + n, 0 + 11 =
11. After the iteration of the second loop, m is updated to 7, n to 5, and x to the sum
of the new values for m + n, 11 + 12 = 23. After the iteration of the third loop, m is
updated to 6, n to 7, and x to the sum of the new values for m + n, 23 + 13 = 36. On
the fourth iteration of the loop, m > n evaluates to false, as 6 < 7 is not true. The
loop ends and the most recent value of x, 36, is output, so the correct answer is option
D.

Question 20

What is the result of the following code snippet?
3: final char a = ‘A’, d = ‘D’;
4: char grade = ‘B’;
5: switch(grade) {
6: case a:
7: case ‘B’: System.out.print(“great”);
8: case ‘C’: System.out.print(“good”); break;
9: case d:
10: case ‘F’: System.out.print(“not good”);
11: }
A. great
B. greatgood
C. The code will not compile because of line 3.
D. The code will not compile because of line 6.
E. The code will not compile because of lines 6 and 9.

Answer 20

B. The code compiles and runs without issue, so options C, D, and E are not correct. The
value of grade is ‘B’ and there is a matching case statement that will cause “great” to
be printed. There is no break statement after the case, though, so the next case state-ment will be reached, and “good” will be printed. There is a break after this case state-ment, though, so the switch statement will end. The correct answer is thus option B.