OCJP Study 08

OCJP(Java 6) 기출문제 연습 8(71~80)

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

QUESTION 71
Given:
3. import java.util.*;
4. public class G1 {
5. public void takeList(List<? extends String> list) {
6. // insert code here
7. }
8. }
Which three code fragments, inserted independently at line 6, will compile? (Choose three.)

A. list.add("foo");
B. Object o = list;
C. String s = list.get(0);
D. list = new ArrayList<String>();
E. list = new ArrayList<Object>();

B,C,D

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QUESTION 72
Given that the elements of a PriorityQueue are ordered according to natural ordering, and:
import java.util.*;
public class GetInLine {
public static void main(String[] args) {
PriorityQueue<String> pq = new PriorityQueue<String>();
pq.add("banana");
pq.add("pear");
pq.add("apple");
System.out.println(pq.poll() + " " + pq.peek());
}
}
What is the result?

A. apple pear
B. banana pear
C. apple apple
D. apple banana
E. banana banana

D

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QUESTION 73
Given:
enum Example { ONE, TWO, THREE }
Which statement is true?

A. The expressions (ONE == ONE) and ONE.equals(ONE) are both guaranteed to be true.
B. The expression (ONE < TWO) is guaranteed to be true and ONE.compareTo(TWO) is guaranteed to be less than one.
C. The Example values cannot be used in a raw java.util.HashMap; instead, the programmer must use a java.util.EnumMap.
D. The Example values can be used in a java.util.SortedSet, but the set will NOT be sorted because enumerated types do NOT implement java.lang.Comparable.

A

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QUESTION 74
Given:
import java.util.*;
public class Mapit {
public static void main(String[] args) {
Set<Integer> set = new HashSet<Integer>();
Integer i1 = 45;
Integer i2 = 46;
set.add(i1);
set.add(i1);
set.add(i2); System.out.print(set.size() + " ");
set.remove(i1); System.out.print(set.size() + " ");
i2 = 47;
set.remove(i2); System.out.print(set.size() + " ");
}
}
What is the result?

A. 2 1 0
B. 2 1 1
C. 3 2 1
D. 3 2 2
E. Compilation fails.
F. An exception is thrown at runtime.

B

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QUESTION 75
Given:
import java.util.*;
public class Explorer1 {
public static void main(String[] args) {
TreeSet<integer> s = new TreeSet<integer>();
TreeSet<integer> subs = new TreeSet<integer>();
for(int i = 606; i < 613; i++)
if(i%2 == 0) s.add(i);
subs = (TreeSet)s.subSet(608, true, 611, true);
s.add(609);
System.out.println(s + " " + subs);
}
}
What is the result?

A. Compilation fails.
B. An exception is thrown at runtime.
C. [608, 609, 610, 612] [608, 610]
D. [608, 609, 610, 612] [608, 609, 610]
E. [606, 608, 609, 610, 612] [608, 610]
F. [606, 608, 609, 610, 612] [608, 609, 610]

F

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QUESTION 76
Given:
import java.util.*;
public class Quest {
public static void main(String[] args) {
String[] colors = {"blue", "red", "green", "yellow", "orange"};
Arrays.sort(colors);
int s2 = Arrays.binarySearch(colors, "orange");
int s3 = Arrays.binarySearch(colors, "violet");
System.out.println(s2 + " " + s3);
}
}
What is the result?

A. 2 -1
B. 2 -4
C. 2 -5
D. 3 -1
E. 3 -4
F. 3 -5
G. Compilation fails.
H. An exception is thrown at runtime.

C

Next item index: (-(number of itens)-1)
ZZZ

QUESTION 77
Given:
HashMap props = new HashMap();
props.put("key45", "some value");
props.put("key12", "some other value");
props.put("key39", "yet another value");
Set s = props.keySet();
//insert code here
What, inserted at line 39, will sort the keys in the props HashMap?

A. Arrays.sort(s);
B. s = new TreeSet(s);
C. Collections.sort(s);
D. s = new SortedSet(s);

B

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QUESTION 78
Which two statements are true? (Choose two.)

A. It is possible to synchronize static methods.
B. When a thread has yielded as a result of yield(), it releases its locks.
C. When a thread is sleeping as a result of sleep(), it releases its locks.
D. The Object.wait() method can be invoked only from a synchronized context.
E. The Thread.sleep() method can be invoked only from a synchronized context.
F. When the thread scheduler receives a notify() request, and notifies a thread, that thread immediately releases its lock.

A,D

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QUESTION 79
Given:
public class TestOne implements Runnable {
public static void main (String[] args) throws Exception {
Thread t = new Thread(new TestOne());
t.start();
System.out.print("Started");
t.join();
System.out.print("Complete");
}
public void run() {
for (int i = 0; i < 4; i++) {
System.out.print(i);
}
}
}
What can be a result?

A. Compilation fails.
B. An exception is thrown at runtime.
C. The code executes and prints "StartedComplete".
D. The code executes and prints "StartedComplete0123".
E. The code executes and prints "Started0123Complete".

E

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QUESTION 80
Which three will compile and run without exception? (Choose three.)

A. private synchronized Object o;
B. void go() {
synchronized() { /* code here */ }
C. public synchronized void go() { /* code here */ }
D. private synchronized(this) void go() { /* code here */ }
E. void go() {
synchronized(Object.class) { /* code here */ }
F. void go() {
Object o = new Object();
synchronized(o) { /* code here */ }

C,E,F

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