OCJP Study 05

OCJP(Java 6) 기출문제 연습 5(41~50)

PC나 스마트폰에서도 동일하게 실행되므로 장소를 가리지 않고 OCJP(JAVA 6) 국제 자격증을 목표로 학습할 수 있다.

QUESTION 41
Given:

int x = 0;
int y = 10;
do {

y--;

++x;
} while (x < 5);
System.out.print(x + "," + y);

What is the result?

A. 5,6
B. 5,5
C. 6,5
D. 6,6

B

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QUESTION 42
Given:

public class Donkey2 {

public static void main(String[] args) {
boolean assertsOn = true;
assert (assertsOn) : assertsOn = true;
if(assertsOn) {

System.out.println("assert is on");
}
}
}

If class Donkey is invoked twice, the first time without assertions enabled, and the second time with assertions enabled, what are the results?

A.
no output
B.
no output
assert is on
C.
assert is on
D.
no output
An AssertionError is thrown.
E.
assert is on
An AssertionError is thrown.

C

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QUESTION 43

Click the Exhibit button.
Given:

public void method() {
Aa= new A();
a.method1();
}

Which statement is true if a TestException is thrown on line 3 of class B?

1. public class A{
2. public void method1() {
3. try {
4.
Bb= new B();
5.
b.method2();
6.
//more code here
7. } catch (TestException te){
8.
throw new RuntimeException(te);
9. }
10. }
11.}
1.
public class B{
2. public void method2() throws TestException {
3. //more code here
4. }
5.
}
1. class TestException extends Exception {
2. }

A. Line 33 must be called within a try block.
B. The exception thrown by method1 in class A is not required to be caught.
C. The method declared on line 31 must be declared to throw a RuntimeException.
D. On line 5 of class A, the call to method2 of class B does not need to be placed in a try/catch block.

B

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QUESTION 44
Given:

Float pi = new Float(3.14f);
if (pi > 3) {

System.out.print("pi is bigger than 3. ");
}
else {

System.out.print("pi is not bigger than 3. ");
}
finally {

System.out.println("Have a nice day.");
}

What is the result?

A. Compilation fails.
B. pi is bigger than 3.
C. An exception occurs at runtime.
D. pi is bigger than 3. Have a nice day.
E. pi is not bigger than 3. Have a nice day.

A

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QUESTION 45
Given:

1. public class Boxer1{
2. Integer i;
3. int x;
4. public Boxer1(int y) {
5. x = i+y;
6. System.out.println(x);
7. }
8. public static void main(String[] args) {
9. new Boxer1(new Integer(4));
10. }
11.}
What is the result?

A. The value "4" is printed at the command line.
B. Compilation fails because of an error in line 5.
C. Compilation fails because of an error in line 9.
D. A NullPointerException occurs at runtime.
E. A NumberFormatException occurs at runtime.
F. An IllegalStateException occurs at runtime.

D

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QUESTION 46
Given:

1.
public class Person {
2. private String name;
3. public Person(String name) { this.name = name; }
4. public boolean equals(Person p) {
5. return p.name.equals(this.name);
6. }
7. }
Which statement is true?

A.
The equals method does NOT properly override the Object.equals method.
B.
Compilation fails because the private attribute p.name cannot be accessed in line 5.
C.
To work correctly with hash-based data structures, this class must also implement the hashCode method.
D.
When adding Person objects to a java.util.Set collection, the equals method in line 4 will prevent duplicates.

A

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QUESTION 47

Which two statements are true about the hashCode method? (Choose two.)

A.
The hashCode method for a given class can be used to test for object equality and object inequality for that class.
B.
The hashCode method is used by the java.util.SortedSet collection class to order the elements within that set.
C.
The hashCode method for a given class can be used to test for object inequality, but NOT object equality, for that class.
D.
The only important characteristic of the values returned by a hashCode method is that the distribution of values must follow a Gaussian distribution.
E.
The hashCode method is used by the java.util.HashSet collection class to group the elements within that set into hash buckets for swift retrieval.

C,E

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QUESTION 48

Given a pre-generics implementation of a method:

11. public static int sum(List list) {
12. int sum = 0;
13. for ( Iterator iter = list.iterator(); iter.hasNext(); ) {
14. int i = ((Integer)iter.next()).intValue();
15. sum += i;
16. }
17. return sum;
18. }
What three changes allow the class to be used with generics and avoid an unchecked warning? (Choose three.)

A. Remove line 14.
B. Replace line 14 with "int i = iter.next();".
C. Replace line 13 with "for (int i : intList) {".
D. Replace line 13 with "for (Iterator iter : intList) {".
E. Replace the method declaration with "sum(List<int> intList)".
F. Replace the method declaration with "sum(List<integer> intList)".

A,C,F

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QUESTION 49
Given:

23. Object [] myObjects = {
24. new Integer(12),
25. new String("foo"),
26. new Integer(5),
27. new Boolean(true)
28. };
29. Arrays.sort(myObjects);
30. for(int i=0; i<myobjects.length; i++){
31. System.out.print(myObjects[i].toString());
32. System.out.print(" ");
33. }
What is the result?

A. Compilation fails due to an error in line 23.
B. Compilation fails due to an error in line 29.
C. A ClassCastException occurs in line 29.
D. A ClassCastException occurs in line 31.
E. The value of all four objects prints in natural order.

C

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QUESTION 50

Given a class Repetition:

1. package utils;
2.
3. public class Repetition {
4. public static String twice(String s) { return s + s; }
5. }
and given another class Demo:

1. public class Demo {
2. public static void main(String[] args) {
3. System.out.println(twice("pizza"));
4. }
5. }
Which code should be inserted at line 1 of Demo.java to compile and run Demo to print "pizzapizza"?

A. import utils.*;
B. static import utils.*;
C. import utils.Repetition.*;
D. static import utils.Repetition.*;
E. import utils.Repetition.twice();
F. import static utils.Repetition.twice;
G. static import utils.Repetition.twice;

F

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