OCJP Study 18

OCJP(Java 6) 기출문제 연습 18(171~180)

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

QUESTION 171
Given classes defined in two different files:
1. package packageA;
2. public class Message {
3. String getText() {
4. return "text";
5. }
6. }
And:
1. package packageB;
2.
3. public class XMLMessage extends packageA.Message {
4. String getText() {
5. return "<msg>text</msg>";
6. }
7.
8. public static void main(String[] args) {
9. System.out.println(new XMLMessage().getText());
10. }
11.}
What is the result of executing XMLMessage.main?

A. text
B. Compilation fails.
C. <msg>text</msg>"
D. An exception is thrown at runtime.

C

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QUESTION 172
Given:
interface Fish {
}
class Perch implements Fish {
}
class Walleye extends Perch {
}
class Bluegill {
}
public class Fisherman {
public static void main(String[] args) {
Fish f = new Walleye();
Walleye w = new Walleye();
Bluegill b = new Bluegill();
if (f instanceof Perch)
System.out.print("f-p ");
if (w instanceof Fish)
System.out.print("w-f ");
if (b instanceof Fish)
System.out.print("b-f ");
}
}
What is the result?

A. w-f
B. f-p w-f
C. w-f b-f
D. f-p w-f b-f
E. Compilation fails.
F. An exception is thrown at runtime.

B

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QUESTION 173
Given:
1. package com.company.application;
2.
3. public class MainClass {
4. public static void main(String[] args) {
5. }
6. }
And MainClass exists in the /apps/com/company/application directory.
Assume the CLASSPATH environment variable is set to "." (current directory).
Which two java commands entered at the command line will run MainClass? (Choose two.)

A. java MainClass if run from the /apps directory
B. java com.company.application.MainClass if run from the /apps directory
C. java -classpath /apps com.company.application.MainClass if run from any directory
D. java -classpath . MainClass if run from the /apps/com/company/application directory
E. java -classpath /apps/com/company/application:. MainClass if run from the /apps directory
F. java com.company.application.MainClass if run from the /apps/com/company/application directory

B,C

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QUESTION 174
Given
class Foo {
static void alpha() {
/* more code here */
}
void beta() {
/* more code here */
}
}
Which two statements are true? (Choose two.)

A. Foo.beta() is a valid invocation of beta().
B. Foo.alpha() is a valid invocation of alpha().
C. Method beta() can directly call method alpha().
D. Method alpha() can directly call method beta().

B,C

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QUESTION 175
Given:
1. public class TestSeven extends Thread {
2. private static int x;
3. public synchronized void doThings() {
4. int current = x;
5. current++;
6. x = current;
7. }
8. public void run() {
9. doThings();
10. }
11.}
Which statement is true?

A. Compilation fails.
B. An exception is thrown at runtime.
C. Synchronizing the run() method would make the class thread-safe.
D. The data in variable "x" are protected from concurrent access problems.
E. Declaring the doThings() method as static would make the class thread-safe.
F. Wrapping the statements within doThings() in a synchronized(new Object()) { } block would make the class thread-safe.

E

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QUESTION 176
Given that the current directory is empty, and that the user has read and write privileges to the current directory, and the following:
1. import java.io.*;
2. public class Maker {
3. public static void main(String[] args) {
4. File dir = new File("dir");
5. File f = new File(dir, "f");
6. }
7. }
Which statement is true?

A. Compilation fails.
B. Nothing is added to the file system.
C. Only a new file is created on the file system.
D. Only a new directory is created on the file system.
E. Both a new file and a new directory are created on the file system.

B

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QUESTION 177
Given:
NumberFormat nf = NumberFormat.getInstance();
nf.setMaximumFractionDigits(4);
nf.setMinimumFractionDigits(2);
String a = nf.format(3.1415926);
String b = nf.format(2);
Which two statements are true about the result if the default locale is Locale.US? (Choose two.)

A. The value of b is 2.
B. The value of a is 3.14.
C. The value of b is 2.00.
D. The value of a is 3.141.
E. The value of a is 3.1415.
F. The value of a is 3.1416.
G. The value of b is 2.0000.

C,F

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QUESTION 178
Which three statements concerning the use of the java.io.Serializable interface are true? (Choose three.)

A. Objects from classes that use aggregation cannot be serialized.
B. An object serialized on one JVM can be successfully deserialized on a different JVM.
C. The values in fields with the volatile modifier will NOT survive serialization and deserialization.
D. The values in fields with the transient modifier will NOT survive serialization and deserialization.
E. It is legal to serialize an object of a type that has a supertype that does NOT implement java.io. Serializable.

B,D,E

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QUESTION 179
Given:
12. String csv = "Sue,5,true,3";
13. Scanner scanner = new Scanner( csv );
14. scanner.useDelimiter(",");
15. int age = scanner.nextInt();
What is the result?

A. Compilation fails.
B. After line 15, the value of age is 5.
C. After line 15, the value of age is 3.
D. An exception is thrown at runtime.

D

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QUESTION 180
Given that c is a reference to a valid java.io.Console object, which two code fragments read a line of text from the console? (Choose two.)

A. String s = c.readLine();
B. char[] c = c.readLine();
C. String s = c.readConsole();
D. char[] c = c.readConsole();
E. String s = c.readLine("%s", "name ");
F. char[] c = c.readLine("%s", "name ");

A,E

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