Certified Java Programmer Mock Exam

Question 1

Which of the following statements is not true?

a. An interface that is declared within the body of a class or interface is known as a nested interface.
b. A constant can be a member of an interface.
c. A class declaration can be a member of an interface.
d. A class that implements an interface must implement all of the methods declared within the interface.
e. None of the above.

Question 2

Which of the following are true statements?

a. Encapsulation is a form of data hiding.
b. A tightly encapsulated class is always immutable.
c. Encapsulation is always used to make programs run faster.
d. Encapsulation helps to protect data from corruption.
e. Encapsulation allows for changes to the internal design of a class while the public interface remains unchanged.

Question 3

Which of the following statements are true?

a. A constructor can invoke another constructor of the same class using the alternate constructor invocation, "this(argumentListopt);".
b. A constructor can invoke itself using the alternate constructor invocation, "this(argumentListopt);".
c. The alternate constructor invocation, "this(argumentListopt);", can legally appear anywhere in the constructor body.
d. A constructor can invoke the constructor of the direct superclass using the superclass constructor invocation, "super(argumentListopt);".
e. The number of constructor invocations that may appear in any constructor body can equal but not exceed the number of alternate constructors declared in the same class.
f. A constructor is not permitted to throw an exception.

Question 4

Which of the following statements are true?

a. An interface declaration can be a member of an interface.
b. A method declared within an interface must have a body represented by empty curly braces.
c. An interface can implement another interface.
d. An abstract class that implements an interface must implement all abstract methods declared within the interface.
e. An abstract method declaration can be a member of an interface.

Question 5

Which of the following are true statements?

a. A top-level class can not be called "tightly encapsulated" unless it is declared private.
b. Encapsulation enhances the maintainability of the code.
c. A tightly encapsulated class allows fast public access to member fields.
d. A tightly encapsulated class allows access to data only through accessor and mutator methods.
e. Encapsulation usually reduces the size of the code.
f. A tightly encapsulated class might have mutator methods that validate data before it is loaded into the internal data model.

Question 6

Suppose that the superclass constructor invocation, "super(argumentListopt);", appears explicitly in a subclass constructor. If a compile-time error is to be avoided then the arguments for the superclass constructor invocation, "super(argumentListopt);", can not refer to which of the following?

a. Static variables declared in this class or any superclass.
b. Instance variables declared in this class or any superclass.
c. Static methods declared in this class or any superclass.
d. Instance methods declared in this class or any superclass.
e. The keyword this.
f. The keyword super.

Question 7

Which of the following are modifiers that can be applied to an interface that is a member of a directly enclosing interface?

a. abstract
b. implements
c. final
d. private
e. protected
f. public

Question 8

A class can not be called "tightly encapsulated" unless which of the following is true?

a. The class is declared final.
b. All local variables are declared private.
c. All method parameters are declared final.
d. No method returns a reference to any object that is referenced by an internal data member.
e. None of the above

Question 9

Which of the following are modifiers that can be applied to an interface that is a member of a directly enclosing class?

a. abstract
b. extends
c. final
d. private
e. protected
f. public

Question 10

A class can not be called "tightly encapsulated" unless which of the following is true?

a. All of the methods are declared private.
b. All of the methods are synchronized.
c. All local variables are declared final.
d. The class is a direct subclass of Object.
e. Accessor methods are used to prevent fields from being set with invalid data.
f. None of the above

Question 11

Which of the following is a modifier that can be applied to an interface that is a member of a directly enclosing class or interface?

a. static
b. synchronized
c. transient
d. volatile
e. implements
f. None of the above.

Question 12

A class can not be called "tightly encapsulated" unless which of the following are true?

a. The data members can not be directly manipulated by external code.
b. The class is declared final.
c. It has no public mutator methods.
d. The superclass is tightly encapsulated.

Question 13

class A {
  String s1 = "A.s1"; String s2 = "A.s2";
}
class B extends A {
  String s1 = "B.s1";
  public static void main(String args[]) {
    B x = new B(); A y = (A)x;
    System.out.println(x.s1+" "+x.s2+" "+y.s1+" "+y.s2);
}}

What is the result of attempting to compile and run the program?

a. Prints: B.s1 A.s2 B.s1 A.s2
b. Prints: B.s1 A.s2 A.s1 A.s2
c. Prints: A.s1 A.s2 B.s1 A.s2
d. Prints: A.s1 A.s2 A.s1 A.s2
e. Run-time error
f. Compile-time error
g. None of the above

Question 14


class A {void m1(A a) {System.out.print("A");}}
class B extends A {void m1(B b) {System.out.print("B");}}
class C extends B {void m1(C c) {System.out.print("C");}}
class D extends C {
  void m1(D d) {System.out.print("D");}
  public static void main(String[] args) {
    A a1 = new A(); B b1 = new B();
    C c1 = new C(); D d1 = new D();
    d1.m1(a1); d1.m1(b1); d1.m1(c1);
}}

What is the result of attempting to compile and run the program?

a. Prints: AAA
b. Prints: ABC
c. Prints: DDD
d. Prints: ABCD
e. Compile-time error
f. Run-time error
g. None of the above

Question 15

class C {
  void printS1() {System.out.print("C.printS1 ");}
  static void printS2() {System.out.print("C.printS2 ");}
}
class D extends C {
  void printS1(){System.out.print("D.printS1 ");}
  void printS2() {System.out.print("D.printS2 ");}
  public static void main (String args[]) {
    C c = new D(); c.printS1(); c.printS2();
}}

What is the result of attempting to compile and run the program?

a. Prints: C.printS1 C.printS2
b. Prints: C.printS1 D.printS2
c. Prints: D.printS1 C.printS2
d. Prints: D.printS1 D.printS2
e. Run-time error
f. Compile-time error
g. None of the above

Question 16

class A {}
class B extends A {}
class C extends B {}
class D {
  void m1(A a) {System.out.print("A");}
  void m1(B b) {System.out.print("B");}
  void m1(C c) {System.out.print("C");}
  public static void main(String[] args) {
    A c1 = new C(); B c2 = new C();
    C c3 = new C(); D d1 = new D();
    d1.m1(c1); d1.m1(c2); d1.m1(c3);
}}

What is the result of attempting to compile and run the program?

a. Prints: AAA
b. Prints: ABC
c. Prints: CCC
d. Compile-time error
e. Run-time error
f. None of the above

Question 17


class E {
  void printS1(){System.out.print("E.printS1 ");}
  static void printS2() {System.out.print("E.printS2");}
}
class F extends E {
  void printS1(){System.out.print("F.printS1 ");}
  static void printS2() {System.out.print("F.printS2");}
  public static void main (String args[]) {
    E x = new F(); x.printS1(); x.printS2();
}}

What is the result of attempting to compile and run the program?

a. Prints: E.printS1 E.printS2
b. Prints: E.printS1 F.printS2
c. Prints: F.printS1 E.printS2
d. Prints: F.printS1 F.printS2
e. Run-time error
f. Compile-time error
g. None of the above

Question 18

class A {void m1(A a) {System.out.print("A");}}
class B extends A {void m1(B b) {System.out.print("B");}}
class C extends B {void m1(C c) {System.out.print("C");}}
class D {
  public static void main(String[] args) {
    A c1 = new C(); B c2 = new C();
    C c3 = new C(); C c4 = new C();
    c4.m1(c1); c4.m1(c2); c4.m1(c3);
}}

What is the result of attempting to compile and run the program?

a. Prints: AAA
b. Prints: ABC
c. Prints: CCC
d. Compile-time error
e. Run-time error
f. None of the above

Question 19

class P {
  static void printS1(){System.out.print("P.printS1 ");}
  void printS2() {System.out.print("P.printS2 ");}
  void printS1S2(){printS1();printS2();}
}
class Q extends P {
  static void printS1(){System.out.print("Q.printS1 ");}
  void printS2(){System.out.print("Q.printS2 ");}
  public static void main(String[] args) {
    new Q().printS1S2();
}}

What is the result of attempting to compile and run the program?

a. Prints: P.printS1 P.printS2
b. Prints: P.printS1 Q.printS2
c. Prints: Q.printS1 P.printS2
d. Prints: Q.printS1 Q.printS2
e. Run-time error
f. Compile-time error
g. None of the above

Question 20

class A {void m1(A a) {System.out.print("A");}}
class B extends A {void m1(B b) {System.out.print("B");}}
class C extends B {void m1(C c) {System.out.print("C");}}
class D {
  public static void main(String[] args) {
    A c1 = new C(); C c2 = new C(); c1.m1(c2);
}}

What is the result of attempting to compile and run the program?

a. Prints: A
b. Prints: B
c. Prints: C
d. Compile-time error
e. Run-time error
f. None of the above

Question 21

class R {
  private void printS1(){System.out.print("R.printS1 ");}
  protected void printS2() {System.out.print("R.printS2 ");}
  protected void printS1S2(){printS1();printS2();}
}
class S extends R {
  private void printS1(){System.out.print("S.printS1 ");}
  protected void printS2(){System.out.print("S.printS2 ");}
  public static void main(String[] args) {
    new S().printS1S2();
}}

What is the result of attempting to compile and run the program?

a. Prints: R.printS1 R.printS2
b. Prints: R.printS1 S.printS2
c. Prints: S.printS1 R.printS2
d. Prints: S.printS1 S.printS2
e. Run-time error
f. Compile-time error
g. None of the above

Question 22

class A {void m1(A a) {System.out.print("A");}}
class B extends A {void m1(B b) {System.out.print("B");}}
class C extends B {void m1(C c) {System.out.print("C");}}
class D {
  public static void main(String[] args) {
    A a1 = new A(); A b1 = new B();
    A c1 = new C(); C c4 = new C();
    a1.m1(c4); b1.m1(c4); c1.m1(c4);
}}

What is the result of attempting to compile and run the program?

a. Prints: AAA
b. Prints: ABC
c. Prints: CCC
d. Compile-time error
e. Run-time error
f. None of the above
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