OCJP Study 17

OCJP(Java 6) 기출문제 연습 17(161~170)

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

QUESTION 161
Given:
public void testIfA() {
if (testIfB("True")) { //Linea 12
System.out.println("True");
} else {
System.out.println("Not true");
}
}
public Boolean testIfB(String str) {
return Boolean.valueOf(str); //Linea 19
}
What is the result when method testIfA is invoked?

A. True
B. Not true
C. An exception is thrown at runtime.
D. Compilation fails because of an error at line 12.
E. Compilation fails because of an error at line 19.

A

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QUESTION 162
Which can appropriately be thrown by a programmer using Java SE technology to create a desktop application?

A. ClassCastException
B. NullPointerException
C. NoClassDefFoundError
D. NumberFormatException
E. ArrayIndexOutOfBoundsException

D

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QUESTION 162
Which two code fragments are most likely to cause a StackOverflowError? (Choose two.)

A. int []x = {1,2,3,4,5};
for(int y = 0; y < 6; y++)
System.out.println(x[y]);
B. static int[] x = {7,6,5,4};
static { x[1] = 8;
x[4] = 3; }
C. for(int y = 10; y < 10; y++)
doStuff(y);
D. void doOne(int x) { doTwo(x); }
void doTwo(int y) { doThree(y); }
void doThree(int z) { doTwo(z); }
E. for(int x = 0; x < 1000000000; x++)
doStuff(x);
F. void counter(int i) { counter(++i); }

D,F

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QUESTION 164
Given:
public static void main(String[] args) {
Integer i = new Integer(1) + new Integer(2);
switch(i) {
case 3: System.out.println("three"); break;
default: System.out.println("other"); break;
}
}
What is the result?

A. three
B. other
C. An exception is thrown at runtime.
D. Compilation fails because of an error on line 12.
E. Compilation fails because of an error on line 13.
F. Compilation fails because of an error on line 15.

A

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QUESTION 165
Given:
public class Tahiti {
Tahiti t;
public static void main(String[] args) {
Tahiti t = new Tahiti();
Tahiti t2 = t.go(t);
t2 = null;
// more code here 11
}
Tahiti go(Tahiti t) {
Tahiti t1 = new Tahiti();
Tahiti t2 = new Tahiti();
t1.t = t2;
t2.t = t1;
t.t = t2;
return t1;
}
}
When line 11 is reached, how many objects are eligible for garbage collection?

A. 0
B. 1
C. 2
D. 3
E. Compilation fails.

A

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QUESTION 165
Given:
public class Commander {
public static void main(String[] args) {
String myProp = /* insert code here Linea 13 */
System.out.println(myProp);
}
}
and the command line: java -Dprop.custom=gobstopper Commander
Which two, placed on line 13, will produce the output gobstopper? (Choose two.)

A. System.load("prop.custom");
B. System.getenv("prop.custom");
C. System.property("prop.custom");
D. System.getProperty("prop.custom");
E. System.getProperties().getProperty("prop.custom");

D,E

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QUESTION 167
Given:
public class ItemTest {
private final int id;
public ItemTest(int id) {
this.id = id;
}
public void updateId(int newId) {
id = newId;
}
public static void main(String[] args) {
ItemTest fa = new ItemTest(42);
fa.updateId(69);
System.out.println(fa.id);
}
}
What is the result?

A. Compilation fails.
B. An exception is thrown at runtime.
C. The attribute id in the ItemTest object remains unchanged.
D. The attribute id in the ItemTest object is modified to the new value.
E. A new ItemTest object is created with the preferred value in the id attribute.

A

The final field ItemTest.id cannot be assigned

QUESTION 167
A developer is creating a class Book, that needs to access class Paper.
The Paper class is deployed in a JAR named myLib.jar.
Which three, taken independently, will allow the developer to use the Paper class while compiling the Book class? (Choose three.)

A. The JAR file is located at $JAVA_HOME/jre/classes/myLib.jar.
B. The JAR file is located at $JAVA_HOME/jre/lib/ext/myLib.jar..
C. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/ myLib.jar/Paper.class.
D. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/ myLib.jar.
E. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac - cp /foo/myLib.jar/ Paper Book.java.
F. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -d /foo/myLib.jar Book.java
G. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac - classpath /foo/ myLib.jar Book.java

B,D,G

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QUESTION 169
Given:
public class Yippee {
public static void main(String[] args) {
for (int x = 1; x < args.length; x++) {
System.out.print(args[x] + " ");
}
}
}
and two separate command line invocations: java Yippee java Yippee 1 2 3 4
What is the result?

A. No output is produced. 1 2 3
B. No output is produced. 2 3 4
C. No output is produced. 1 2 3 4
D. An exception is thrown at runtime. 1 2 3
E. An exception is thrown at runtime. 2 3 4
F. An exception is thrown at runtime. 1 2 3 4

B

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QUESTION 170
Click the Exhibit button.
class Foo {
private int x;
public Foo( int x ){ this.x = x;}
public void setX( int x ) { this.x = x; }
public int getX(){ return x;}
}
public class Gamma {
static Foo fooBar(Foo foo) {
foo = new Foo(100);
return foo;
}
public static void main(String[] args) {
Foo foo = new Foo( 300 );
System.out.println( foo.getX() + "-");
Foo fooFoo = fooBar(foo);
System.out.println(foo.getX() + "-");
System.out.println(fooFoo.getX() + "-");
foo = fooBar( fooFoo);
System.out.println( foo.getX() + "-");
System.out.println(fooFoo.getX());
}
}
What is the output of the program shown in the exhibit?

A. 300-100-100-100-100
B. 300-300-100-100-100
C. 300-300-300-100-100
D. 300-300-300-300-100

B

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