Page: 2
4. Flow Control
11. Given:
class Swill {
public static void main(String[] args) {
String s = "-";
switch(TimeZone.CST) {
case EST: s += "e";
case CST: s += "c";
case MST: s += "m";
default: s += "X";
case PST: s += "p";
}
System.out.println(s);
}
}
enum TimeZone {EST, CST, MST, PST }
What is the result?
A. -c
B. -X
C. -cm
D. -cmp
E. -cmXp
F. Compilation fails.
G. An exception is thrown at runtime.
Answer:
-> E is correct. It’s legal to use enums in a switch, and normal switch fall-through logic applies; i.e., once a match is made the switch has been entered, and all remaining blocks will run if no break statement is encountered. Note: default doesn’t have to be last.
-> A, B, C, D, and F are incorrect based on the above.
(Objective 2.1)
12. Given:
class Circus {
public static void main(String[] args) {
int x = 9;
int y = 6;
for(int z = 0; z < 6; z++, y--) {
if(x > 2) x--;
label:
if(x > 5) {
System.out.print(x + " ");
--x;
continue label;
}
x--;
}
}
}
What is the result?
A. 8
B. 8 7
C. 8 7 6
D. Compilation fails.
E. An exception is thrown at runtime.
Answer:
-> D is correct. A labeled continue works only with loops. In this case, although the label is
legal, label is not a label on a loop statement, it’s a label on an if statement.
-> A, B, C, and E are incorrect based on the above. (Objective 2.2)
13. Given:
1. class Loopy {
2. public static void main(String[] args) {
3. int[] x = {7,6,5,4,3,2,1};
4. // insert code here
5. System.out.print(y + " ");
6. }
7. } }
Which, inserted independently at line 4, compiles? (Choose all that apply.)
A. for(int y : x) {
B. for(x : int y) {
C. int y = 0; for(y : x) {
D. for(int y=0, z=0; z<x.length; z++) { y = x[z];
E. for(int y=0, int z=0; z<x.length; z++) { y = x[z];
F. int y = 0; for(int z=0; z<x.length; z++) { y = x[z];
Answer:
-> A , D, and F are correct. A is an example of the enhanced for loop. D and F are examples of the basic for loop.
-> B is incorrect because its operands are swapped. C is incorrect because the enhanced
for must declare its first operand. E is incorrect syntax to declare two variables in a for statement. (Objective 2.2)
14. Given:
1. class Ring {
2. final static int x2 = 7;
3. final static Integer x4 = 8;
4. public static void main(String[] args) {
5. Integer x1 = 5;
6. String s = "a";
7. if(x1 < 9) s += "b";
8. switch(x1) {
9. case 5: s += "c";
10. case x2: s += "d";
11. case x4: s += "e";
12. }
13. System.out.println(s);
14. }
15. }
What is the result?
A. abc
B. abcde
C. Compilation fails due only to an error on line 7.
D. Compilation fails due only to an error on line 8.
E. Compilation fails due only to an error on line 10.
F. Compilation fails due only to an error on line 11.
G. Compilation fails due to errors on multiple lines.
Answer:
-> F is correct. A switch statement requires its case expressions to be constants, and wrapper variables (even final static ones) aren’t considered constants. The rest of the code is correct.
-> A, B, C, D, E, and G are incorrect based on the above. (Objective 2.1)
Page: 2
1
2