OCJP Study 21

OCJP(Java 6) 기출문제 연습 21(201~210)

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

QUESTION 201
Given:
11. String test = "This is a test";
12. String[] tokens = test.split("\s");
13. System.out.println(tokens.length);
What is the result?

A. 0
B. 1
C. 4
D. Compilation fails.
E. An exception is thrown at runtime.

D

Invalid escape sequence (valid ones are \b \t \n \f \r \" \' \\ )

QUESTION 202
Given:
import java.io.*;
class Animal {
Animal() {
System.out.print("a");
}
}
class Dog extends Animal implements Serializable {
Dog() {
System.out.print("d");
}
}
public class Beagle extends Dog {
}
If an instance of class Beagle is created, then Serialized, then deSerialized, what is the result?

A. ad
B. ada
C. add
D. adad
E. Compilation fails.
F. An exception is thrown at runtime.

B

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QUESTION 203
Given:
11. double input = 314159.26;
12. NumberFormat nf = NumberFormat.getInstance(Locale.ITALIAN);
13. String b;
14. //insert code here
Which code, inserted at line 14, sets the value of b to 314.159,26?

A. b = nf.parse( input );
B. b = nf.format( input );
C. b = nf.equals( input );
D. b = nf.parseObject( input );

B

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QUESTION 204
A team of programmers is involved in reviewing a proposed design for a new utility class.
After some discussion, they realize that the current design allows other classes to access methods in the utility class that should be accessible only to methods within the utility class itself.
What design issue has the team discovered?

A. Tight coupling
B. Low cohesion
C. High cohesion
D. Loose coupling
E. Weak encapsulation
F. Strong encapsulation

E

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QUESTION 205
Given a method that must ensure that its parameter is not null:
11. public void someMethod(Object value) {
12. // check for null value
...
20. System.out.println(value.getClass());
21. }
What, inserted at line 12, is the appropriate way to handle a null value?

A. assert value == null;
B. assert value != null, "value is null";
C. if (value == null) { throw new AssertionException("value is null"); }
D. if (value == null) { throw new IllegalArgumentException("value is null"); }

D

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QUESTION 206 Given:
class Alpha {
public void foo() { System.out.print("Afoo "); }
}
public class Beta extends Alpha {
public void foo() { System.out.print("Bfoo "); }
public static void main(String[] args) {
Alpha a = new Beta();
Beta b = (Beta)a;
a.foo();
b.foo();
}
}
What is the result?

A. Afoo Afoo
B. Afoo Bfoo
C. Bfoo Afoo
D. Bfoo Bfoo
E. Compilation fails.
F. An exception is thrown at runtime.

D

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QUESTION 207
Given:
1. public class Target {
2. private int i = 0;
3. public int addOne() {
4. return ++i;
5. }
6. }
And:
1. public class Client {
2. public static void main(String[] args){
3. System.out.println(new Target().addOne());
4. }
5. }
Which change can you make to Target without affecting Client?

A. Line 4 of class Target can be changed to return i++;
B. Line 2 of class Target can be changed to private int i = 1;
C. Line 3 of class Target can be changed to private int addOne(){
D. Line 2 of class Target can be changed to private Integer i = 0;

D

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QUESTION 208
Given:
class Animal {
public String noise() {
return "peep";
}
}
class Dog extends Animal {
public String noise() {
return "bark";
}
}
class Cat extends Animal {
public String noise() {
return "meow";
}
} ...
30. Animal animal = new Dog();
31. Cat cat = (Cat)animal;
32. System.out.println(cat.noise());
What is the result?

A. peep
B. bark
C. meow
D. Compilation fails.
E. An exception is thrown at runtime.

E

Exception in thread "main" java.lang.ClassCastException: Dog cannot be cast to Cat
at Client.main(Client.java:12)

QUESTION 209
Given:
abstract class A {
abstract void a1();
void a2() {
}
}
class B extends A {
void a1() {
}
void a2() {
}
}
class C extends B {
void c1() {
}
}
And:
A x = new B();
C y = new C();
A z = new C();
What are four valid examples of polymorphic method calls? (Choose four.)

A. x.a2();
B. z.a2();
C. z.c1();
D. z.a1();
E. y.c1();
F. x.a1();

A,B,D,F

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QUESTION 210
Given:
class Employee {
String name;
double baseSalary;
Employee(String name, double baseSalary) {
this.name = name;
this.baseSalary = baseSalary;
}
}
public class SalesPerson extends Employee {
double commission;
public SalesPerson(String name, double baseSalary, double commission) {
// insert code here Line 13
}
}
Which two code fragments, inserted independently at line 13, will compile? (Choose two.)

A. super(name, baseSalary);
B. this.commission = commission;
C. super(); this.commission = commission;
D. this.commission = commission; super();
E. super(name, baseSalary); this.commission = commission;
F. this.commission = commission; super(name, baseSalary);
G. super(name, baseSalary, commission);

A,E

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