SCJP Questions 151-160

Question 151
Click the Exhibit button.
1. public class SimpleCalc {
2. public int value;
3. public void calculate() { value += 7; }
4. }
And:
1. public class MultiCalc extends SimpleCalc {
2. public void calculate() { value -= 3; }
3. public void calculate(int multiplier) {
4. calculate();
5. super.calculate();
6. value *=multiplier;
7. }
8. public static void main(String[] args) {
9. MultiCalc calculator = new MultiCalc();
10. calculator.calculate(2);
11. System.out.println(”Value is: “+ calculator.value);
12. }
13. }
What is the result?
A. Value is: 8
B. Compilation fails.
C. Value is: 12
D. Value is: -12
E. The code runs with no output.
F. An exception is thrown at runtime.
Answer: A

Question 152
Given:
10. public class Hello {
11. String title;
12. int value;
13. public Hello() {
14. title += “ World”;
15. }
16. public Hello(int value) {
17. this.value = value;
18. title = “Hello”;
19. Hello();
20. }
21. }
and:
30. Hello c = new Hello(5);
31. System.out.println(c.title);
What is the result?
A. Hello
B. Hello World
C. Compilation fails.
D. Hello World 5
E. The code runs with no output.
F. An exception is thrown at runtime.
Answer: C

Question 153
Click the Exhibit button.
1. public class Car {
2. private int wheelCount;
3. private String vin;
4. public Car(String vin) {
5. this.vin = vin;
6. this.wheelCount = 4;
7. }
8. public String drive() {
9. return “zoom-zoom”;
10. }
11. public String getInfo() {
12. return “VIN: “+ vin + “wheels: “+ wheelCount;
13. }
14. }
And:
1. public class MeGo extends Car {
2. public MeGo(String vin) {
3. this.wheelCount = 3;
4. }
5. }
What two must the programmer do to correct the compilation errors?
(Choose two.)
A. insert a call to this() in the Car constructor
B. insert a call to this() in the MeGo constructor
C. insert a call to super() in the MeGo constructor
D. insert a call to super(vin) in the MeGo constructor
E. change the wheelCount variable in Car to protected
F. change line 3 in the MeGo class to super.wheelCount = 3;
Answer: DE

Question 154
Click the Exhibit button.
1. public class Employee {
2. String name;
3. double baseSalary;
4. Employee(String name, double baseSalary) {
5. this.name = name;
6. this.baseSalary = baseSalary;
7. }
8. }
And:
1. public class Salesperson extends Employee {
2. double commission;
3. public Salesperson(String name, double baseSalary,
4. double commission) {
5. // insert code here
6. }
7. }
Which code, inserted at line 7, completes the Salesperson constructor?
A. this.commission = commission;
B. superb();
commission = commission;
C. this.commission = commission;
superb();
D. super(name, baseSalary);
this.commission = commission;
E. super();
this.commission = commission;
F. this.commission = commission;
super(name, baseSalary);
Answer: D

Question 155
Given:
1. public class Blip {
2. protected int blipvert(int x) { return 0; }
3. }
4. class Vert extends Blip {
5. // insert code here
6. }
Which five methods, inserted independently at line 5, will compile?
(Choose five.)
A. public int blipvert(int x) { return 0; }
B. private int blipvert(int x) { return 0; }
C. private int blipvert(long x) { return 0; }
D. protected long blipvert(int x) { return 0; }
E. protected int blipvert(long x) { return 0; }
F. protected long blipvert(long x) { return 0; }
G. protected long blipvert(int x, int y) { return 0; }
Answer: ACEFG

Question156
Given:
10. public class Foo {
11. public int a;
12. public Foo() { a = 3; }
13. public void addFive() { a += 5; }
14. }
and:
20. public class Bar extends Foo {
21. public int a;
22. public Bar() { a = 8; }
23. public void addFive() { this.a +=5; }
24. }
invoked with:
30. Foo foo = new Bar();
31. foo.addFive();
32. System.out.println(”Value: “+ foo.a);
What is the result?
A. Value: 3
B. Value: 8
C. Value: 13
D. Compilation fails.
E. The code runs with no output.
F. An exception is thrown at runtime.
Answer: A

Question 157
Given:
10. public class SuperCaic {
11. protected static int multiply(int a, int b) { return a * b; }
12. }
and:
20. public class SubCalc extends SuperCalc {
21. public static int multiply(int a, int b) {
22. int c = super.multiply(a, b);
23. return c;
24. }
25. }
and:
30. SubCalc sc = new SubCalc();
31. System.out.println(sc.multiply(3,4));
32. System.out.println(SubCalc.multiply(2,2));
What is the result?
A. 12
4
B. The code runs with no output.
C. An exception is thrown at runtime.
D. Compilation fails because of an error in line 21.
E. Compilation fails because of an error in line 22.
F. Compilation fails because of an error in line 31.
Answer: E

Question 158
Given:
1. public class Team extends java.util.LinkedList {
2. public void addPlayer(Player p) {
3. add(p);
4. }
5. public void compete(Team opponent) { /* more code here */ }
6. }
7. class Player { /* more code here */ }
Which two are true? (Choose two.)
A. This code will compile.
B. This code demonstrates proper design of an is-a relationship.
C. This code demonstrates proper design of a has-a relationship.
D. A Java programmer using the Team class could remove Player
objects from a Team object.
Answer: AD

Question 159
Which four are true? (Choose four.)
A. Has-a relationships should never be encapsulated.
B. Has-a relationships should be implemented using inheritance.
C. Has-a relationships can be implemented using instance variables.
D. Is-a relationships can be implemented using the extends keyword.
E. Is-a relationships can be implemented using the implements
keyword.
F. The relationship between Movie and Actress is an example of an is-a
relationship.
G. An array or a collection can be used to implement a one-to-many
has-a relationship.
Answer: CDEG

Question 160
Which two are true about has-a and is-a relationships? (Choose two.)
A. Inheritance represents an is-a relationship.
B. Inheritance represents a has-a relationship.
C. Interfaces must be used when creating a has-a relationship.
D. Instance variables can be used when creating a has-a relationship.
Answer: AD

SCJP Questions 141-150

Question 141
Given:
10. abstract class A {
11. abstract void al();
12. void a2() { }
13. }
14. class B extends A {
15. void a1() { }
16. void a2() { }
17. }
18. class C extends B { void c1() { } }
and:
A x = new B(); C y = new C(); A z = new C();
Which four are 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();
Answer: ABDF

Question 142
Given:
10. interface A { void x(); }
11. class B implements A { public void x() { } public voidy() { } }
12. class C extends B { public void x() {} }
And:
20. java.util.List<A> list = new java.util.ArrayList<A>();
21. list.add(new B());
22. list.add(new C());
23. for (A a:list) {
24. a.x();
25. a.y();;
26. }
What is the result?
A. The code runs with no output.
B. An exception is thrown at runtime.
C. Compilation fails because of an error in line 20.
D. Compilation fails because of an error in line 21.
E. Compilation fails because of an error in line 23.
F. Compilation fails because of an error in line 25.
Answer: F

Question 143
Given:
1. class SuperClass {
2. public A getA() {
3. return new A();
4. }
5. }
6. class SubClass extends SuperClass {
7. public B getA() {
8. return new B();
9. }
10. }
Which is true?
A. Compilation will succeed if A extends B.
B. Compilation will succeed if B extends A.
C. Compilation will always fail because of an error in line 7.
D. Compilation will always fail because of an error in line 8.
Answer: B

Question 144
Given:
1. interface A { public void aMethod(); }
2. interface B { public void bMethod(); }
3. interface C extends A,B { public void cMethod(); }
4. class D implements B {
5. public void bMethod() { }
6. }
7. class E extends D implements C {
8. public void aMethod() { }
9. public void bMethod() { }
10. public void cMethod() { }
11. }
What is the result?
A. Compilation fails because of an error in line 3.
B. Compilation fails because of an error in line 7.
C. Compilation fails because of an error in line 9.
D. If you define D e = new E(), then e.bMethod() invokes the version
of bMethod() defined in Line 5.
E. If you define D e = (D)(new E()), then e.bMethod() invokes the
version of bMethod() defined in Line 5.
F. If you define D e = (D)(new E()), then e.bMethod() invokes the
version of bMethod() defined in Line 9.
Answer: F

Question 145
Given:
10. interface A { public int getValue() }
11. class B implements A {
12. public int getValue() { return 1; }
13. }
14. class C extends B {
15. // insert code here
16. }
Which three code fragments, inserted individually at line 15, make use
of polymorphism? (Choose three.)
A. public void add(C c) { c.getValue(); }
B. public void add(B b) { b.getValue(); }
C. public void add(A a) { a.getValue(); }
D. public void add(A a, B b) { a.getValue(); }
E. public void add(C c1, C c2) { c1.getValue(); }
Answer: BCD

Question 146
Given:
1. class ClassA {
2. public int numberOfinstances;
3. protected ClassA(int numberOfinstances) {
4. this.numberOflnstances = numberOfinstances;
5. }
6. }
7. public class ExtendedA extends ClassA {
8. private ExtendedA(int numberOfinstances) {
9. super(numberOflnstances);
10. }
11. public static void main(String[] args) {
12. ExtendedA ext = new ExtendedA(420);
13. System.out.print(ext.numberOflnstances);
14. }
15. }
Which is true?
A. 420 is the output.
B. An exception is thrown at runtime.
C. All constructors must be declared public.
D. Constructors CANNOT use the private modifier.
E. Constructors CANNOT use the protected modifier.
Answer: A

Question 147
147. Given:
1. public class Base {
2. public static final String FOO = “foo”;
3. public static void main(String[] args) {
4. Base b = new Base();
5. Sub s = new Sub();
6. System.out.print(Base.FOO);
7. System.out.print(Sub.FOO);
8. System.out.print(b.FOO);
9. System.out.print(s.FOO);
10. System.out.print(((Base)s).FOO);
11. } }
12. class Sub extends Base {public static final String FOO=bar;}
What is the result?
A. foofoofoofoofoo
B. foobarfoobarbar
C. foobarfoofoofoo
D. foobarfoobarfoo
E. barbarbarbarbar
F. foofoofoobarbar
G. foofoofoobarfoo
Answer: D

Question 148
Which three statements are true? (Choose three.)
A. A final method in class X can be abstract if and only if X is abstract.
B. A protected method in class X can be overridden by any subclass of
X.
C. A private static method can be called only within other static
methods in class X.
D. A non-static public final method in class X can be overridden in any
subclass of X.
E. A public static method in class X can be called by a subclass of X
without explicitly referencing the class X.
F. A method with the same signature as a private final method in class
X can be implemented in a subclass of X.
G. A protected method in class X can be overridden by a subclass of A
only if the subclass is in the same package as X.
Answer: BEF

Question 149
Given:
1. class Pizza {
2. java.util.ArrayList toppings;
3. public final void addTopping(String topping) {
4. toppings.add(topping);
5. }
6. }
7. public class PepperoniPizza extends Pizza {
8. public void addTopping(String topping) {
9. System.out.println(”Cannot add Toppings”);
10. }
11. public static void main(String[] args) {
12. Pizza pizza = new PepperoniPizza();
13. pizza.addTopping(”Mushrooms”);
14. }
15. }
What is the result?
A. Compilation fails.
B. Cannot add Toppings
C. The code runs with no output.
D. A NullPointerException is thrown in Line 4.
Answer: A

Question 150
Given:
1. class Super {
2. private int a;
3. protected Super(int a) { this.a = a; }
4. }
.....
11. class Sub extends Super {
12. public Sub(int a) { super(a); }
13. public Sub() { this.a= 5; }
14. }
Which two, independently, will allow Sub to compile? (Choose two.)
A. Change line 2 to:
public int a;
B. Change line 2 to:
protected int a;
C. Change line 13 to:
public Sub() { this(5); }
D. Change line 13 to:
public Sub() { super(5); }
E. Change line 13 to:
public Sub() { super(a); }
Answer: CD

SCJP Questions 131-14

Question 131
Click the Exhibit button.
1. class Computation extends Thread {
2.
3. private int num;
4. private boolean isComplete;
5. private int result;
6.
7. public Computation(int num) { this.num = num; }
8.
9. public synchronized void run() {
10. result = num * 2;
11. isComplete = true;
12. notify();
13. }
14.
15. public synchronized int getResult() {
16. while (!isComplete) {
17. try {
18. wait();
19. } catch (InterruptedException e) { }
20. }
21. return result;
22. }
23.
24. public static void main(String[] args) {
25. Computation[] computations = new Computation [4];
26. for (int i = 0; i < computations.length; i++) {
27. computations[i] = new Computation(i);
28. computations[i] .start();
29. }
30. for (Computation c : computations)
31. System.out.print(c.getResult() +“ “);
32. }
33. }
What is the result?
A. The code will deadlock.
B. The code may run with no output.
C. An exception is thrown at runtime.
D. The code may run with output “0 6”.
E. The code may run with output “2 0 6 4’.
F. The code may ruin with output “0 2 4 6”.
Answer: F

Question 132
Given:
7. void waitForSignal() {
8. Object obj = new Object();
9. synchronized (Thread.currentThread()) {
10. obj.wait();
11. obj.notify();;
12. }
13. }
Which is true?
A. This code may throw an InterruptedException.
B. This code may throw an IllegalStateException.
C. This code may throw a TimeoutException after ten minutes.
D. This code will not compile unless “obj.wait()” is replaced with
“((Thread) obj).wait()”.
E. Reversing the order of obj.wait() and obj.notify() may cause this
method to complete normally.
F. A call to notify() or notifyAll() from another thread may cause this
method to complete normally.
Answer: B

Question 133
Given:
foo and bar are public references available to many other threads. foo
refers to a Thread and bar is an Object. The thread foo is currently
executing bar.wait(). From another thread, which statement is the
most reliable way to ensue that foo will stop executing wait()?
A. foo.notify();
B. bar.notify();
C. foo.notifyAll();
D. Thread.notify();
E. bar.notiFYAll();
F. Object.notify();
Answer: E

Question 134
Which two are true? (Choose two.)
A. An encapsulated, public class promotes re-use.
B. Classes that share the same interface are always tightly
encapsulated.
C. An encapsulated class allows subclasses to overload methods, but
does NOT allow overriding methods.
D. An encapsulated class allows a programmer to change an
implementation without affecting outside code.
Answer: AD

Question 135
Given:
1. package test;
2.
3. class Target {
4. public String name = “hello”;
5. }
What can directly access and change the value of the variable name?
A. any class
B. only the Target class
C. any class in the test package
D. any class that extends Target
Answer: C

Question 136
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;
Answer: D

Question 137
Given:
1. package geometry;
2. public class Hypotenuse {
3. public InnerTriangle it = new InnerTriangle();
4. class InnerTriangle {
5. public int base;
6. public int height;
7. }
8. }
Which is true about the class of an object that can reference the
variable base?
A. It can be any class.
B. No class has access to base.
C. The class must belong to the geometry package.
D. The class must be a subclass of the class Hypotenuse.
Answer: C

Question 138
Given:
11. class ClassA {}
12. class ClassB extends ClassA {}
13. class ClassC extends ClassA {}
and:
21. ClassA p0 = new ClassA();
22. ClassB p1 = new ClassB();
23. ClassC p2 = new ClassC();
24. ClassA p3 = new ClassB();
25. ClassA p4 = new ClassC();
Which three are valid? (Choose three.)
A. p0 = p1;
B. p1 =p2;
C. p2 = p4;
D. p2 = (ClassC)p1;
E. p1 = (ClassB)p3;
F. p2 = (ClassC)p4;
Answer: AEF

Question 139
Given:
11. class Animal { public String noise() { return “peep”; } }
12. class Dog extends Animal {
13. public String noise() { return “bark”; }
14. }
15. class Cat extends Animal {
16. public String noise() { return “meow”; }
17. }
.....
30. Animal animal = new Dog();
31. Cat cat = (Cat)animal;
32. System.out.printIn(cat.noise());
What is the result?
A. peep
B. bark
C. meow
D. Compilation fails.
E. An exception is thrown at runtime.
Answer: E

Question 140
Given:
11. abstract class Vehicle { public int speed() { return 0; } }
12. class Car extends Vehicle { public int speed() { return 60; } }
13. class RaceCar extends Car { public int speed() { return 150; }}
......
21. RaceCar racer = new RaceCar();
22. Car car = new RaceCar();
23. Vehicle vehicle = new RaceCar();
24. System.out.println(racer.speed() + “, ‘ + car.speed()
25. + “, “+ vehicle.speed());
What is the result?
A. 0, 0,0
B. 150, 60, 0
C. Compilation fails.
D. 150, 150, 150
E. An exception is thrown at runtime.
Answer: D

SCJP Questions 121-130

Question 121
Given:
1. public class TestOne {
2. public static void main (String[] args) throws Exception {
3. Thread.sleep(3000);
4. System.out.println(”sleep”);
5. }
6. }
What is the result?
A. Compilation fails.
B. An exception is thrown at runtime.
C. The code executes normally and prints “sleep”.
D. The code executes normally, but nothing is printed.
Answer: C

Question 122
Given:
1. public class TestOne implements Runnable {
2. public static void main (String[] args) throws Exception {
3. Thread t = new Thread(new TestOne());
4. t.start();
5. System.out.print(”Started”);
6. t.join();
7. System.out.print(”Complete”);
8. }
9. public void run() {
10. for (int i= 0; i< 4; i++) {
11. System.out.print(i);
12. }
13. }
14. }
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 “Started0l23Complete”.
Answer: E

Question 123
Click the Exhibit button.
Given:
1. public class TwoThreads {
2
3. private static Object resource = new Object();
4.
5. private static void delay(long n) {
6. try { Thread.sleep(n); }
7. catch (Exception e) { System.out.print(”Error “); }
8. }
9
10. public static void main(String[] args) {
11. System.out.print(”StartMain “);
12. new Thread1().start();
13. delay(1000);
14. Thread t2 = new Thread2();
15. t2.start();
16. delay(1000);
17. t2.interrupt
18. delay(1000);
19. System.out.print(”EndMain “);
20. }
21.
22. static class Thread 1 extends Thread {
23. public void run() {
24. synchronized (resource) {
25. System.out.print(”Startl “);
26. delay(6000);
27. System.out.print(”End1 “);
28. }
29. }
30. }
31.
32. static class Thread2 extends Thread {
33. public void run() {
34. synchronized (resource) {
35. System.out.print(”Start2 “);
36. delay(2000);
37. System.out.print(”End2 “);
38. }
39. }
40. }
41. }
Assume that sleep(n) executes in exactly m milliseconds, and all other
code executes in an insignificant amount of time. What is the output if
the main() method is run?
A. Compilation fails.
B. Deadlock occurs.
C. StartMain Start1 Error EndMain End1
D. StartMain Start1 EndMain End1 Start2 End2
E. StartMain Start1 Error Start2 EndMain End2 End1
F. StartMain Start1 Start2 Error End2 EndMain End1
G. StartMain Start1 EndMain End1 Start2 Error End2
Answer: G

Question 124
Given:
public class NamedCounter {
private final String name;
private int count;
public NamedCounter(String name) { this.name = name; }
public String getName() { return name; }
public void increment() { coount++; }
public int getCount() { return count; }
public void reset() { count = 0; }
}
Which three changes should be made to adapt this class to be used
safely by multiple threads? (Choose three.)
A. declare reset() using the synchronized keyword
B. declare getName() using the synchronized keyword
C. declare getCount() using the synchronized keyword
D. declare the constructor using the synchronized keyword
E. declare increment() using the synchronized keyword
Answer: ACE

Question 125
Click the Exhibit button:
1. public class Threads 1 {
2. intx=0;
3. public class Runner implements Runnable {
4. public void run() {
5. int current = 0;
6. for(int=i=0;i<4;i++){
7. current = x;
8. System.out.print(current + “, “);
9. x = current + 2;
10. }
11. }
12. }
13.
14. public static void main(String[] args) {
15. new Threads1().go();
16. }
17.
18. public void go() {
19. Runnable r1 = new Runner();
20. new Thread(r1).start();
21. new Thread(r1 ).start();
22. }
23. }
Which two are possible results? (Choose two.)
A. 0, 2, 4, 4, 6, 8, 10, 6,
B. 0, 2, 4, 6, 8, 10, 2, 4,
C. 0, 2, 4, 6, 8, 10, 12, 14,
D. 0, 0, 2, 2, 4, 4, 6, 6, 8, 8, 10, 10, 12, 12, 14, 14,
E. 0, 2, 4, 6, 8, 10, 12, 14, 0, 2, 4, 6, 8, 10, 12, 14,
Answer: AC

Question 126
Click the Exhibit button.
1. import java.util.*;
2.
3. public class NameList {
4. private List names = new ArrayList();
5. public synchronized void add(String name) { names.add(name); }
6. public synchronized void printAll() {
7. for (int i = 0; i <names.size(); i++) {
8. System.out.print(names.get(i) +“ “);
9. }
10. }
11. public static void main(String[] args) {
12. final NameList sl = new NameList();
13.for(int i=0;i<2;i++) {
14. new Thread() {
15. public void ruin() {
16. sl.add(”A”);
17. sl.add(”B”);
18. sl.add(”C”);
19. sl.printAll();
20. }
21. }.start();
22. }
23. }
24. }
Which two statements are true if this class is compiled and run?
(Choose two.)
A. An exception may be thrown at runtime.
B. The code may run with no output, without exiting.
C. The code may run with no output, exiting normally.
D. The code may rum with output “A B A B C C “, then exit.
E. The code may rum with output “A B C A B C A B C “, then exit.
F. The code may ruin with output “A A A B C A B C C “, then exit.
G. The code may ruin with output “A B C A A B C A B C “, then exit.
Answer: EG

Question 127
Given:
1. public class TestFive {
2. private int x;
3. public void foo() {
4 int current = x;
5. x = current + 1;
6. }
7. public void go() {
8. for(int i=0;i<5;i++) {
9. new Thread() {
10. public void run() {
11. foo();
12. System.out.print(x + “, “);
13. } }.start();
14. }}}
Which two changes, taken together, would guarantee the output: 1, 2,
3, 4, 5, ? (Choose two.)
A. Move the line 12 print statement into the foo() method.
B. Change line 7 to public synchronized void go() {.
C. Change the variable declaration on line 3 to private volatile int x;.
D. Wrap the code inside the foo() method with a synchronized( this )
block.
E. Wrap the for loop code inside the go() method with a synchronized
block synchronized(this) { // for loop code here }.
Answer: AD

Question 128
Which three will compile and rim 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 */ }
}
Answer: CEF

Question 129
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. }
1 1.}
Which 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.
Answer: E

Question 130
Click the Exhibit button.
10. public class Transfers {
11. public static void main(String[] args) throws Exception {
12. Record r1 = new Record();
13. Record r2 = new Record();
14. doTransfer(r1, r2, 5);
15. doTransfer(r2, r1, 2);
16. doTransfer(r1, r2, 1);
17. // print the result
18. System.out.println(”rl = “ + r1.get() +“, r2=” + r2.get());
19. }
20. private static void doTransfer(
21. final Record a, final Record b, final int amount) {
22. Thread t = new Thread() {
23. public void run() {
24. new Clerk().transfer(a, b, amount);
25. }
26. };
27. t.start();
28. }
29. }
30. class Clerk {
31. public synchronized void transfer(Record a, Record b, int amount){
32. synchronized (a) {
33. synchronized (b) {
34. a.add(-amount);
35. b.add(amount);
36. }
37. }
38. }
39. }
40. class Record {
41.int num=10;
42. public int get() { return num; }
43. public void add(int n) { num = num + n; }
44. }
If Transfers.main() is run, which three are true? (Choose three.)
A. The output may be “r1 = 6, r2 = 14”.
B. The output may be “r1 = 5, r2 = 15”.
C. The output may be “r1 = 8, r2 = 12”.
D. The code may run (and complete) with no output.
E. The code may deadlock (without completing) with no output.
F. M IllegalStateException or InterruptedException may be thrown at
runtime.
Answer: ABE

SCJP Questions 111-120

Question 111
Given:
11. String test = “Test A. Test B. Test C.”;
12. // insert code here
13. String[] result = test.split(regex);
Which regular expression inserted at line 12 will correctly split test into
“Test A,” “Test B,” and “Test C”?
A. String regex = “”;
B. String regex = “ “;
C. String regex = “.*“.
D. String regex = “\\s”
E. String regex = “\\.\\s*”;
F. String regex = “\\w[ \.] +“;
Answer: E

Question 112
Given:
12. System.out.format(”Pi is approximately %d.”, Math.PI);
What is the result?
A. Compilation fails.
B. Pi is approximately 3.
C. Pi is approximately 3.141593.
D. An exception is thrown at runtime.
Answer: D

Question 113
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.
Answer: D

Question 114
Which two code fragments will execute the method doStuff() in a
separate thread? (Choose two.)
A. new Thread() {
public void run() { doStuff(); }
}
B. new Thread() {
public void start() { doStuff(); }
}
C. new Thread() {
public void start() { doStuff(); }
} .run();
D. new Thread() {
public void run() { doStuff(); }
} .start();
E. new Thread(new Runnable() {
public void run() { doStuff(); }
} ).run();
F. new Thread(new Runnable() {
public void run() { doStuff(); }
}).start();
Answer: DF

Question 115
Given:
1. public class Threads3 implements Runnable {
2. public void run() {
3. System.out.print(”running”);
4. }
5. public static void main(String[] args) {
6. Thread t = new Thread(new Threads3());
7. t.run();
8. t.run();
9. t.start();
10. }
11. }
What is the result?
A. Compilation fails.
B. An exception is thrown at runtime.
C. The code executes and prints “running”.
D. The code executes and prints “runningrunning”.
E. The code executes and prints “runningrunningrunning”.
Answer: E

Question 116
Given:
1. public class Threads4 {
2. public static void main (String[] args) {
3. new Threads4().go();
4. }
5. public void go() {
6. Runnable r = new Runnable() {
7. public void run() {
8. System.out.print(”foo”);
9. }
10. };
11. Thread t = new Thread(r);
12. t.start();
13. t.start();
14. }
15. }
What is the result?
A. Compilation fails.
B. An exception is thrown at runtime.
C. The code executes normally and prints ‘foo”.
D. The code executes normally, but nothing is printed.
Answer: B

Question 117
Given:
1. public class Threads5 {
2. public static void main (String[] args) {
3. new Thread(new Runnable() {
4. public void run() {
5. System.out.print(”bar”);
6. }}).start();
7. }
8. }
What is the result?
A. Compilation fails.
B. An exception is thrown at runtime.
C. The code executes normally and prints “bar”.
D. The code executes normally, but nothing prints.
Answer: C

Question 118
Given:
11. Runnable r = new Runnable() {
12. public void run() {
13. System.out.print(”Cat”);
14. }
15. };
16. Threadt=new Thread(r) {
17. public void run() {
18. System.out.print(”Dog”);
19. }
20. };
21. t.start();
What is the result?
A. Cat
B. Dog
C. Compilation fails.
D. The code runs with no output.
E. An exception is thrown at runtime.
Answer: B

Question 119
Click the Exhibit button.
Given:
10. public class Starter extends Thread {
11. private int x= 2;
12. public static void main(String[] args) throws Exception {
13. new Starter().makeItSo();
14. }
15. public Starter() {
16. x=5;
17. start();
18. }
19. public void makeItSo() throws Exception {
20. join();
21. x=x- 1;
22. System.out.println(x);
23. }
24. public void run() { x *= 2; }
25. }
What is the output if the main() method is rum?
A. 4
B. 5
C. 8
D. 9
E. Compilation fails.
F. An exception is thrown at runtime.
G. It is impossible to determine for certain.
Answer: D

Question 120
Given:
1. public class Threads2 implements Runnable {
2.
3. public void nun() {
4. System.out.println(”run.”);
5. throw new RuntimeException(”Problem”);
6. }
7. public static void main(String[] args) {
8. Thread t = new Thread(new Threads2());
9. t.start();
10. System.out.println(”End of method.”);
11. }
12. }
Which two can be results? (Choose two.)
A. java.lang.RuntimeException: Problem
B. run.
java.lang.RuntimeException: Problem
C. End of method.
java.lang.RuntimeException: Problem
D. End of method.
run.
java.lang.RuntimeException: Problem
E. run.
java.lang.RuntimeException: Problem
End of method.
Answer: DE

SCJP Questions 101-110

Question 100
Assuming that the serializeBanana() and the deserializeBanana()
methods will correctly use Java serialization and given:
13. import java.io.*;
14. class Food implemertts Serializable {int good = 3;}
15. class Fruit externds Food {int juice = 5;}
16. public class Banana extends Fruit {
17. int yellow = 4;
18. public static void main(String [] args) {
19. Banana b = new Banana(); Banana b2 = new Banana();
20. b.serializeBanana(b); // assume correct serialization
21. b2 = b.deserializeBanana(); // assume correct
22. System.out.println(”restore “+b2.yellow+ b2.juice+b2.good);
24. }
25. // more Banana methods go here
50. }
‘What is the result?
A. restore 400
B. restore 403
C. restore 453
D. Compilation fails.
E. An exception is thrown at runtime.
Answer: C

Question 101
Assuming that the serializeBanana2() and the deserializeBanana2()
methods will correctly use Java serialization and given:
13. import java.io.*;
14. class Food {Food() { System.out.print(”1”); } }
15. class Fruit extends Food implements Serializable {
16. Fruit() { System.out.print(”2”); } }
17. public class Banana2 extends Fruit { int size = 42;
18. public static void main(String [] args) {
19. Banana2 b = new Banana2();
20. b.serializeBanana2(b); // assume correct serialization
21. b = b.deserializeBanana2(b); // assume correct
22. System.out.println(” restored “+ b.size + “ “); }
23. // more Banana2 methods
24. }
What is the result?
A. Compilation fails.
B. 1 restored 42
C. 12 restored 42
D. 121 restored 42
E. 1212 restored 42
F. An exception is thrown at runtime.
Answer: D

Question 102
Given:
10. public class Foo implements java.io.Serializable {
11. private int x;
12. public int getX() { return x; }
12.publicFoo(int x){this.x=x; }
13. private void writeObject( ObjectOutputStream s)
14. throws IOException {
15. // insert code here
16. }
17. }
Which code fragment, inserted at line 15, will allow Foo objects to be
correctly serialized and deserialized?
A. s.writeInt(x);
B. s.serialize(x);
C. s.writeObject(x);
D. s.defaultWriteObject();
Answer: D

Question 103
Given:
12. NumberFormat nf= NumberFormat.getInstance();
13. nf.setMaximumFractionDigits(4);
14. nf.setMinimumFractionDigits(2);
15. String a = nf.format(3.1415926);
16. String b = nf.format(2);
Which two 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.
Answer: CF

Question 104
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 3 14.159,26?
A. b = nf.parse( input);
B. b = nf.format( input);
C. b = nf.equals( input);
D. b = nf.parseObject( input);
Answer: B

Question 105
Given:
14. DateFormat df;
15. Date date = new Date();
16. //insert code here
17. String s = df.format( date);
Which two, inserted independently at line 16, allow the code to
compile? (Choose two.)
A. df= new DateFormat();
B. df= Date.getFormatter();
C. df= date.getFormatter();
D. df= date.getDateFormatter();
E. df= Date.getDateFormatter();
F. df= DateFormat.getInstance();
G. df = DateFormat.getDateInstance();
Answer: FG

Question 106
Given:
12. Date date = new Date();
13. df.setLocale(Locale.ITALY);
14. String s = df.format(date);
The variable df is an object of type DateFormat that has been
initialized in line 11. What is the result if this code is run on December
14, 2000?
A. The value of s is 14-dic-2004.
B. The value of s is Dec 14, 2000.
C. An exception is thrown at runtime.
D. Compilation fails because of an error in line 13.
Answer: D

Question 107
Given:
33. Date d = new Date(0);
34. String ds = “December 15, 2004”;
35. // insert code here
36. try {
37. d = df.parse(ds);
38. }
39. catch(ParseException e) {
40. System.out.println(”Unable to parse “+ ds);
41. }
42. // insert code here too
Which will create the appropriate DateFormat object and add a day to
the Date object?
A. 35. DateFormat df= DateFormat.getDateFormat();
42. d.setTime( (60 * 60 * 24) + d.getTime());
B. 35. DateFormat df= DateFormat.getDateJnstance();
42. d.setTime( (1000 * 60 * 60 * 24) + d.getTime());
C. 35. DateFormat df= DateFormat.getDateFormat();
42. d.setLocalTime( (1000*60*60*24) + d.getLocalTime());
D. 35. DateFormat df= DateFormat.getDateJnstance();
42. d.setLocalTime( (60 * 60 * 24) + d.getLocalTime());
Answer: B

Question 108
Given a valid DateFormat object named df, and
16. Date d = new Date(0L);
17. String ds = “December 15, 2004”;
18. // insert code here
What updates d’s value with the date represented by ds?
A. 18. d = df.parse(ds);
B. 18. d = df.getDate(ds);
C. 18. try {
19. d = df.parse(ds);
20. } catch(ParseException e) { };
D. 18. try {
19. d = df.getDate(ds);
20. } catch(ParseException e) { };
Answer: C

Question 109
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.
Answer: D

Question 110
Given:
11. String test= “a1b2c3”;
12. String[] tokens = test.split(”\\d”);
13. for(String s: tokens) System.out.print(s +“ “);
What is the result?
A. a b c
B. 1 2 3
C. a1b2c3
D. a1 b2 c3
E. Compilation fails.
F. The code runs with no output.
G. An exception is thrown at runtime.
Answer: A

SCJP Questions 91-100

Question 91
Given:
11. public String makinStrings() {
12. String s = “Fred”;
13. s = s + “47”;
14. s = s.substring(2, 5);
15. s = s.toUpperCase();
16. return s.toString();
17. }
How many String objects will be created when this method is invoked?
A. 1
B. 2
C. 3
D. 4
E. 5
F. 6
Answer: C

Question 92
Given:
1. public class TestString3 {
2. public static void main(String[] args) {
3. // insert code here
5. System.out.println(s);
6. }
7. }
Which two code fragments, inserted independently at line 3, generate
the output 4247? (Choose two.)
A. String s = “123456789”;
s = (s-”123”).replace(1,3,”24”) - “89”;
B. StringBuffer s = new StringBuffer(”123456789”);
s.delete(0,3).replace( 1,3, “24”).delete(4,6);
C. StringBuffer s = new StringBuffer(”123456789”);
s.substring(3,6).delete( 1 ,3).insert( 1, “24”);
D. StringBuilder s = new StringBuilder(”123456789”);
s.substring(3,6).delete( 1 ,2).insert( 1, “24”);
E. StringBuilder s = new StringBuilder(”123456789”);
s.delete(0,3).delete( 1 ,3).delete(2,5).insert( 1, “24”);
Answer: BE

Question 93
Given:
11. public class Yikes {
12.
13. public static void go(Long n) {System.out.println(”Long “);}
14. public static void go(Short n) {System.out.println(”Short “);}
15. public static void go(int n) {System.out.println(”int “);}
16. public static void main(String [] args) {
17. short y= 6;
18. long z= 7;
19. go(y);
20. go(z);
21. }
22. }
What is the result?
A. int Long
B. Short Long
C. Compilation fails.
D. An exception is thrown at runtime.
Answer: A

Question 94
Given:
12. public class Wow {
13. public static void go(short n) {System.out.println(”short”); }
14. public static void go(Short n) {System.out.println(”SHORT”);}
15. public static void go(Long n) {System.out.println(” LONG”); }
16. public static void main(String [] args) {
17. Short y= 6;
18.int z=7;
19. go(y);
20. go(z);
21. }
22. }
What is the result?
A. short LONG
B. SHORT LONG
C. Compilation fails.
D. An exception is thrown at runtime.
Answer: C

Question 95
Given:
10. class MakeFile {
11. public static void main(String[] args) {
12. try {
13. File directory = new File(”d”);
14. File file = new File(directory,”f”);
15. if(!file.exists()) {
16. file.createNewFile();
17. }
18. } catch (IOException e) {
19. e.printStackTrace
20. }
21. }
22. }
The current directory does NOT contain a directory named “d.”
Which three are true? (Choose three.)
A. Line 16 is never executed.
B. An exception is thrown at runtime.
C. Line 13 creates a File object named “d.”
D. Line 14 creates a File object named “f.’
E. Line 13 creates a directory named “d” in the file system.
F. Line 16 creates a directory named “d” and a file ‘f’ within it in the
file system.
G. Line 14 creates a file named ‘f’ inside of the directory named “d” in
the file system.
Answer: BCD

Question 96
When comparing java.io.BufferedWriter to java.io.FileWriter, which
capability exists as a method in only one of the two?
A. closing the stream
B. flushing the stream
C. writing to the stream
D. marking a location in the stream
E. writing a line separator to the stream
Answer: E

Question 97
Given:
12. import java.io.*;
13. public class Forest implements Serializable {
14. private Tree tree = new Tree();
15. public static void main(String [] args) {
16. Forest f= new Forest();
17. try {
18. FileOutputStream fs = new FileOutputStream(”Forest.ser”);
19. ObjectOutputStream os = new ObjectOutputStream(fs);
20. os.writeObject(f); os.close();
21. } catch (Exception ex) { ex.printStackTrace(); }
22. } }
23.
24. class Tree { }
What is the result?
A. Compilation fails.
B. An exception is thrown at runtime.
C. An instance of Forest is serialized.
D. A instance of Forest and an instance of Tree are both serialized.
Answer: B

Question 98
Click the Exhibit button.
1. import java.io.*;
2. public class Foo implements Serializable {
3. public int x, y;
4. public Foo( int x, int y) { this.x = x; this.y = y; }
5.
6. private void writeObject( ObjectOutputStream s)
7. throws IOException {
8. s.writeInt(x); s.writeInt(y)
9. }
10.
11. private void readObject( ObjectInputStream s)
12. throws IOException, ClassNotFoundException {
13.
14. // insert code here
15.
16. }
17. }
Which code, inserted at line 14, will allow this class to correctly
serialize and deserialize?
A. s.defaultReadObject();
B. this = s.defaultReadObject();
C. y = s.readInt(); x = s.readInt();
D. x = s.readInt(); y = s.readInt();
Answer: D

Question 99
Which three concerning the use of the java.io.Serializable interface are
true? (Choose three.)
A. Objects from classes that use aggregation cannot be serialized.
B. Art 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.
Answer: BDE

Question 100
Assuming that the serializeBanana() and the deserializeBanana()
methods will correctly use Java serialization and given:
13. import java.io.*;
14. class Food implemertts Serializable {int good = 3;}
15. class Fruit externds Food {int juice = 5;}
16. public class Banana extends Fruit {
17. int yellow = 4;
18. public static void main(String [] args) {
19. Banana b = new Banana(); Banana b2 = new Banana();
20. b.serializeBanana(b); // assume correct serialization
21. b2 = b.deserializeBanana(); // assume correct
22. System.out.println(”restore “+b2.yellow+ b2.juice+b2.good);
24. }
25. // more Banana methods go here
50. }
‘What is the result?
A. restore 400
B. restore 403
C. restore 453
D. Compilation fails.
E. An exception is thrown at runtime.
Answer: C