CS II Chapter 13 Quiz, CS II Chapter 12 Quiz, CS II Chapter 11 Quiz, CS II Chapter 19 Quiz, 18

Analyze the following code: public class Test { public static void main(String[] args) throws MyException { System.out.println("Welcome to Java"); } } class MyException extends Error { } A. You should not declare a class that extends Error, because Error raises a fatal error that terminates the program. B. You cannot declare an exception in the main method. C. You declared an exception in the main method, but you did not throw it. D. The program has a compile error

A

Analyze the following program. public class Test { public static void main(String[] args) { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; System.out.println("Welcome to Java"); } catch (Exception ex) { System.out.println(ex); } } } A. An exception is raised due to Integer.parseInt(s); B. An exception is raised due to 2 / i; C. The program has a compile error. D. The program compiles and runs without exceptions

A

Assume Calendar calendar = new GregorianCalendar(). __________ returns the month of the year. A. calendar.get(Calendar.MONTH) B. calendar.get(Calendar.MONTH_OF_YEAR) C. calendar.get(Calendar.WEEK_OF_MONTH) D. calendar.get(Calendar.WEEK_OF_YEAR)

A

What exception type does the following program throw? public class Test { public static void main(String[] args) { System.out.println(1 / 0); } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. ClassCastException E. No exception

A

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { method(); System.out.println("After the method call"); } catch (NumberFormatException ex) { System.out.println("NumberFormatException"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } } static void method() { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; System.out.println("Welcome to Java"); } } A. The program displays NumberFormatException. B. The program displays NumberFormatException followed by After the method call. C. The program displays NumberFormatException followed by RuntimeException. D. The program has a compile error. E. The program displays RuntimeException

A

Which class contains the method for checking whether a file exists? A. File B. PrintWriter C. Scanner D. System

A

Which of the following statements are correct? I: File file = new File("input.txt"); try (Scanner input = new Scanner(file)) { String line = input.nextLine(); } II: try (File file = new File("input.txt"); Scanner input = new Scanner(file);) { String line = input.nextLine(); } III: File file; try (file = new File("input.txt"); Scanner input = new Scanner(file);) { String line = input.nextLine(); } IV: File file; Scanner input; try (file = new File("input.txt"); input = new Scanner(file);) { String line = input.nextLine(); } A. I B. II C. III D. IV

A

Which of the following statements is incorrect? A. Integer i = 4.5; B. Double i = 4.5; C. Object i = 4.5; D. Number i = 4.5;

A

Which of the following statements regarding abstract methods is false? A. An abstract class can have instances created using the constructor of the abstract class. B. An abstract class can be extended. C. A subclass of a non-abstract superclass can be abstract. D. A subclass can override a concrete method in a superclass to declare it abstract. E. An abstract class can be used as a data type

A

Which method can be used to create an output object for file temp.txt? A. new PrintWriter("temp.txt") B. new PrintWriter(temp.txt) C. new PrintWriter(new File("temp.txt")) D. new PrintWriter(File("temp.txt"))

A and C

Which of the following statements are true? A. A class should describe a single entity and all the class operations should logically fit together to support a coherent purpose. B. A class should always contain a no-arg constructor. C. The constructors must always be public. D. The constructors may be protected

A and D

Suppose you enter 34.3, the ENTER key, 57.8, the ENTER key, abc, the Enter key. Analyze the following code. 1 Scanner input = new Scanner(System.in); 2 double v1 = input.nextDouble(); 3 double v2 = input.nextDouble(); 4 String line = input.nextLine(); A. After line 2 is executed, v1 is 34.3. B. After line 3 is executed, v2 is 57.8. C. After line 4 is executed, line contains an empty string. D. After line 4 is executed, line is null. E. After line 4 is executed, line contains character "abc"

A, B and C

Suppose you enter 34.3, the ENTER key, 57.8, the ENTER key. Analyze the following code. 1 Scanner input = new Scanner(System.in); 2 double v1 = input.nextDouble(); 3 double v2 = input.nextDouble(); 4 String line = input.nextLine(); A. After line 2 is executed, v1 is 34.3. B. After line 3 is executed, v2 is 57.8. C. After line 4 is executed, line contains an empty string. D. After line 4 is executed, line is null. E. After line 4 is executed, line contains character "\n"

A, B and C

Which of the following statements are correct? I: try (PrintWriter output = new PrintWriter("output.txt")) { output.println("Welcome to Java"); } II: try (PrintWriter output = new PrintWriter("output.txt");) { output.println("Welcome to Java"); } III: PrintWriter output; try (output = new PrintWriter("output.txt");) { output.println("Welcome to Java"); } IV: try (PrintWriter output = new PrintWriter("output.txt");) { output.println("Welcome to Java"); } finally { output.close(); } A. I B. II C. III D. IV

A, B and C

The GeometricObject and Circle classes are defined in this chapter. Analyze the following code. Which statements are correct? public class Test { public static void main(String[] args) { GeometricObject x = new Circle(3); GeometricObject y = (Circle)(x.clone()); System.out.println(x); System.out.println(y); } } A. The program has a compile error because the clone() method is protected in the Object class. B. After you override the clone() method and make it public in the Circle class, the problem can compile and run just fine, but y is null if Circle does not implement the Cloneable interface. C. To enable a Circle object to be cloned, the Circle class has to override the clone() method and implement the java.lang.Cloneable interface. D. If GeometricObject implements Cloneable and Circle overrides the clone() method, the clone() method will work fine to clone Circle objects

A, B, C and D

Which of the following statements are true? A. Inheritance models the is-a relationship between two classes. B. A strong is-a relationship describes a direct inheritance relationship between two classes. C. A weak is-a relationship describes that a class has certain properties. D. A strong is-a relationship can be represented using class inheritance. E. A weak is-a relationship can be represented using interfaces

A, B, C, D and E

Which of the following statements are true? A. To override a method, the method must be defined in the subclass using the same signature and compatible return type as in its superclass. B. Overloading a method is to provide more than one method with the same name but with different signatures to distinguish them. C. It is a compile error if two methods differ only in return type in the same class. D. A private method cannot be overridden. If a method defined in a subclass is private in its superclass, the two methods are completely unrelated. E. A static method cannot be overridden. If a static method defined in the superclass is redefined in a subclass, the method defined in the superclass is hidden

A, B, C, D and E

An instance of _________ are unchecked exceptions. A. RuntimeException B. Exception C. Error D. Throwable E. NumberFormatException

A, C and E

Which of the following statements are true? A. A method can be overloaded in the same class. B. A method can be overridden in the same class. C. If a method overloads another method, these two methods must have the same signature. D. If a method overrides another method, these two methods must have the same signature. E. A method in a subclass can overload a method in the superclass

A, D and E

Analyze the following code: public class Test { public static void main(String[] args) { new B(); } } class A { int i = 7; public A() { System.out.println("i from A is " + i); } public void setI(int i) { this.i = 2 * i; } } class B extends A { public B() { setI(20); // System.out.println("i from B is " + i); } @Override public void setI(int i) { this.i = 3 * i; } } A. The constructor of class A is not called. B. The constructor of class A is called and it displays "i from A is 7". C. The constructor of class A is called and it displays "i from A is 40". D. The constructor of class A is called and it displays "i from A is 60"

B

Analyze the following code: public class Test { public static void main(String[] args) { try { int zero = 0; int y = 2/zero; try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException } catch(Exception e) { } } catch(RuntimeException e) { System.out.println(e); } } } A. A try-catch block cannot be embedded inside another try-catch block. B. A good programming practice is to avoid nesting try-catch blocks, because nesting makes programs difficult to read. You can rewrite the program using only one try-catch block. C. The program has a compile error because Exception appears before RuntimeException. D. None of the above.

B

Object-oriented programming allows you to derive new classes from existing classes. This is called ____________. A. encapsulation B. inheritance C. abstraction D. generalization

B

Suppose you create a class Square to be a subclass of GeometricObject. Analyze the following code: class Square extends GeometricObject { double length; Square(double length) { GeometricObject(length); } } A. The program compiles fine, but you cannot create an instance of Square because the constructor does not specify the length of the Square. B. The program has a compile error because you attempted to invoke the GeometricObject class's constructor illegally. C. The program compiles fine, but it has a runtime error because of invoking the Square class's constructor illegally

B

Suppose you enter 34.3 57.8 789, then press the ENTER key. Analyze the following code. Scanner input = new Scanner(System.in); int v1 = input.nextInt(); int v2 = input.nextInt(); String line = input.nextLine(); A. After the last statement is executed, v1 is 34. B. The program has a runtime error because 34.3 is not an integer. C. After the last statement is executed, line contains characters '7', '8', '9', '\n'. D. After the last statement is executed, line contains characters '7', '8', '9'

B

The getValue() method is overridden in two ways. Which one is correct? I: public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); } } class B { public String getValue() { return "Any object"; } } class A extends B { public Object getValue() { return "A string"; } } II: public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); } } class B { public Object getValue() { return "Any object"; } } class A extends B { public String getValue() { return "A string"; } }

B

The java.util.Calendar and java.util.GregorianCalendar classes are introduced in Chapter 11. Analyze the following code. Which of the following statements is correct? 1. import java.util.*; 2. public class Test { 3. public static void main(String[] args) { 4. Calendar[] calendars = new Calendar[10]; 5. calendars[0] = new Calendar(); 6. calendars[1] = new GregorianCalendar(); 7. } 8. } A. The program has a compile error on Line 4 because java.util.Calendar is an abstract class. B. The program has a compile error on Line 5 because java.util.Calendar is an abstract class. C. The program has a compile error on Line 6 because Calendar[1] is not of a GregorianCalendar type. D. The program has no compile errors

B

What exception type does the following program throw? public class Test { public static void main(String[] args) { int[] list = new int[5]; System.out.println(list[5]); } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. ClassCastException E. No exception

B

What is displayed on the console when running the following program? public class Test { public static void main (String[] args) { try { System.out.println("Welcome to Java"); return; } finally { System.out.println("The finally clause is executed"); } } } A. Welcome to Java B. Welcome to Java followed by The finally clause is executed in the next line C. The finally clause is executed D. None of the above

B

What is displayed on the console when running the following program? public class Test { public static void main (String[] args) { try { System.out.println("Welcome to Java"); } finally { System.out.println("The finally clause is executed"); } } } A. Welcome to Java B. Welcome to Java followed by The finally clause is executed in the next line C. The finally clause is executed D. None of the above

B

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { System.out.println("Welcome to Java"); int i = 0; int y = 2 / i; System.out.println("Welcome to HTML"); } finally { System.out.println("The finally clause is executed"); } } } A. Welcome to Java, then an error message. B. Welcome to Java followed by The finally clause is executed in the next line, then an error message. C. The program displays three lines: Welcome to Java, Welcome to HTML, The finally clause is executed, then an error message. D. None of the above.

B

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { System.out.println("Welcome to Java"); int i = 0; int y = 2/i; System.out.println("Welcome to Java"); } catch (RuntimeException ex) { System.out.println("Welcome to Java"); } finally { System.out.println("End of the block"); } } } A. The program displays Welcome to Java three times followed by End of the block. B. The program displays Welcome to Java two times followed by End of the block. C. The program displays Welcome to Java three times. D. The program displays Welcome to Java two times

B

What is wrong in the following program? public class Test { public static void main (String[] args) { try { System.out.println("Welcome to Java"); } } } A. You cannot have a try block without a catch block. B. You cannot have a try block without a catch block or a finally block. C. A method call that does not declare exceptions cannot be placed inside a try block. D. Nothing is wrong

B

Which class do you use to write data into a text file? A. File B. PrintWriter C. Scanner D. System

B

Which method can be used to read a whole line from the file? A. next B. nextLine C. nextInt D. nextDouble

B

Which method can be used to write data? A. close B. print C. exist D. rename

B

Which of the following declares an abstract method in an abstract Java class? A. public abstract method(); B. public abstract void method(); C. public void abstract method(); D. public void method() {} E. public abstract void method() {}

B

Which of the following is not an advantage of Java exception handling? A. Java separates exception handling from normal processing tasks. B. Exception handling improves performance. C. Exception handling makes it possible for the caller's caller to handle the exception. D. Exception handling simplifies programming because the error-reporting and error-handling code can be placed at the catch block

B

Which of the following returns the path separator character? A. File.pathSeparator B. File.pathSeparatorChar C. File.separator D. File.separatorChar E. None of the above

B

Which of the following statements creates an instance of File on Window for the file c:\temp.txt? A. new File("c:\temp.txt") B. new File("c:\\temp.txt") C. new File("c:/temp.txt") D. new File("c://temp.txt")

B

Analyze the following code: public class Test extends A { public static void main(String[] args) { Test t = new Test(); t.print(); } } class A { String s; A(String s) { this.s = s; } public void print() { System.out.println(s); } } A. The program does not compile because Test does not have a default constructor Test(). B. The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor. The program would compile if the constructor in the class A were removed. C. The program would compile if a default constructor A(){ } is added to class A explicitly. D. The program compiles, but it has a runtime error due to the conflict on the method name print.

B and C

Which of the following statements are true? A. A subclass is a subset of a superclass. B. A subclass is usually extended to contain more functions and more detailed information than its superclass. C. "class A extends B" means A is a subclass of B. D. "class A extends B" means B is a subclass of A

B and C

Analyze the following code: public class A extends B { } class B { public B(Strign s) { } } A. The program has a compile error because A does not have a default constructor. B. The program has a compile error because the default constructor of A invokes the default constructor of B, but B does not have a default constructor. C. The program would compile fine if you add the following constructor into A: A(String s) { } D. The program would compile fine if you add the following constructor into A: A(String s) { super(s); }

B and D

Analyze the following code: public class Test1 { public Object max(Object o1, Object o2) { if ((Comparable)o1.compareTo(o2) >= 0) { return o1; } else { return o2; } } } A. The program has a compile error because Test1 does not have a main method. B. The program has a compile error because o1 is an Object instance and it does not have the compareTo method. C. The program has a compile error because you cannot cast an Object instance o1 into Comparable. D. The program would compile if ((Comparable)o1.compareTo(o2) >= 0) is replaced by (((Comparable)o1).compareTo(o2) >= 0)

B and D

Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a no-arg constructor. Which of the following is correct? A. A a = new A(); B. A a = new B(); C. B b = new A(); D. B b = new B();

B and D

Suppose A is an interface, B is a concrete class with a no-arg constructor that implements A. Which of the following is correct? A. A a = new A(); B. A a = new B(); C. B b = new A(); D. B b = new B();

B and D

An instance of _________ describes system errors. If this type of error occurs, there is little you can do beyond notifying the user and trying to terminate the program gracefully. A. RuntimeException B. Exception C. Error D. Throwable E. NumberFormatException

C

Analyze the following code. Which of the following statements is correct? public class Test { public static void main(String[] args) { Number x = new Integer(3); System.out.println(x.intValue()); System.out.println(x.compareTo(new Integer(4))); } } A. The program has a compile error because an Integer instance cannot be assigned to a Number variable. B. The program has a compile error because intValue is an abstract method in Number. C. The program has a compile error because x does not have the compareTo method. D. The program compiles and runs fine

C

The java.lang.Number and its subclasses are introduced in Chapter 11. Analyze the following code. Number numberRef = new Integer(0); Double doubleRef = (Double)numberRef; Which of the following statements is correct? A. There is no such class named Integer. You should use the class Int. B. The compiler detects that numberRef is not an instance of Double. C. A runtime class casting exception occurs, since numberRef is not an instance of Double. D. The program runs fine, since Integer is a subclass of Double. E. You can convert an int to double, so you can cast an Integer instance to a Double instance

C

The relationship between an interface and the class that implements it is A. Composition B. Aggregation C. Inheritance D. None

C

To create an InputStream to read from a file on a Web server, you use the method __________ in the URL class. A. getInputStream(); B. obtainInputStream(); C. openStream(); D. connectStream();

C

What exception type does the following program throw? public class Test { public static void main(String[] args) { String s = "abc"; System.out.println(s.charAt(3)); } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. ClassCastException E. No exception

C

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { System.out.println("Welcome to Java"); int i = 0; double y = 2.0 / i; System.out.println("Welcome to HTML"); } finally { System.out.println("The finally clause is executed"); } } } A. Welcome to Java. B. Welcome to Java followed by The finally clause is executed in the next line. C. The program displays three lines: Welcome to Java, Welcome to HTML, The finally clause is executed. D. None of the above.

C

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { System.out.println("Welcome to Java"); int i = 0; int y = 2/i; System.out.println("Welcome to Java"); } catch (RuntimeException ex) { System.out.println("Welcome to Java"); } finally { System.out.println("End of the block"); } System.out.println("End of the block"); } } A. The program displays Welcome to Java three times followed by End of the block. B. The program displays Welcome to Java two times followed by End of the block. C. The program displays Welcome to Java two times followed by End of the block two times. D. You cannot catch RuntimeException errors

C

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { method(); System.out.println("After the method call"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } catch (Exception ex) { System.out.println("Exception"); } } static void method() throws Exception { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; System.out.println("Welcome to Java"); } catch (NumberFormatException ex) { System.out.println("NumberFormatException"); throw ex; } catch (RuntimeException ex) { System.out.println("RuntimeException"); } } } A. The program displays NumberFormatException twice. B. The program displays NumberFormatException followed by After the method call. C. The program displays NumberFormatException followed by RuntimeException. D. The program has a compile error

C

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { method(); System.out.println("After the method call"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } catch (Exception ex) { System.out.println("Exception"); } } static void method() throws Exception { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; System.out.println("Welcome to Java"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } catch (Exception ex) { System.out.println("Exception"); } } } A. The program displays RuntimeException twice. B. The program displays Exception twice. C. The program displays RuntimeException followed by After the method call. D. The program displays Exception followed by RuntimeException. E. The program has a compile error

C

What is the best suitable relationship between Employee and Faculty? A. Composition B. Aggregation C. Inheritance D. None

C

What is the output of running class C? class A { public A() { System.out.println( "The default constructor of A is invoked"); } } class B extends A { public B() { System.out.println( "The default constructor of B is invoked"); } } public class C { public static void main(String[] args) { B b = new B(); } } A. Nothing displayed B. "The default constructor of B is invoked" C. "The default constructor of A is invoked" followded by "The default constructor of B is invoked" D. "The default constructor of B is invoked" followed by "The default constructor of A is invoked" E. "The default constructor of A is invoked"

C

Which class do you use to read data from a text file? A. File B. PrintWriter C. Scanner D. System

C

Which method can be used to create an input object for file temp.txt? A. new Scanner("temp.txt") B. new Scanner(temp.txt) C. new Scanner(new File("temp.txt")) D. new Scanner(File("temp.txt"))

C

Which of the following class definitions defines a legal abstract class? A. class A { abstract void unfinished() { } } B. class A { abstract void unfinished(); } C. abstract class A { abstract void unfinished(); } D. public class abstract A { abstract void unfinished(); }

C

Which of the statements regarding the super keyword is incorrect? A. You can use super to invoke a super class constructor. B. You can use super to invoke a super class method. C. You can use super.super.p to invoke a method in superclass's parent class. D. You cannot invoke a method in superclass's parent class

C

Analyze the following code: public class Test { public static void main(String[] args) { Object a1 = new A(); Object a2 = new Object(); System.out.println(a1); System.out.println(a2); } } class A { int x; @Override public String toString() { return "A's x is " + x; } } A. The program cannot be compiled, because System.out.println(a1) is wrong and it should be replaced by System.out.println(a1.toString()); B. When executing System.out.println(a1), the toString() method in the Object class is invoked. C. When executing System.out.println(a2), the toString() method in the Object class is invoked. D. When executing System.out.println(a1), the toString() method in the A class is invoked

C and D

Given the following code, find the compile error. public class Test { public static void main(String[] args) { m(new GraduateStudent()); m(new Student()); m(new Person()); m(new Object()); } public static void m(Student x) { System.out.println(x.toString()); } } class GraduateStudent extends Student { } class Student extends Person { @Override public String toString() { return "Student"; } } class Person extends Object { @Override public String toString() { return "Person"; } } A. m(new GraduateStudent()) causes an error B. m(new Student()) causes an error C. m(new Person()) causes an error D. m(new Object()) causes an error

C and D

The Rational class in this chapter is defined as a subclass of java.lang.Number. Which of the following expressions is correct? A. Rational.doubleValue(); B. Rational.doubleValue("5/4"); C. new Rational(5, 4).doubleValue(); D. new Rational(5, 4).toDoubleValue(); E. new Rational(5, 4).intValue();

C and E

Which of the following are incorrect? A. An abstract class contains constructors. B. The constructors in an abstract class should be protected. C. The constructors in an abstract class are private. D. You may declare a final abstract class. E. An interface may contain constructors

C, D and E

Analyze the following code. Which of the following statements is correct? public class Test { public static void main(String[] args) { Number x = new Integer(3); System.out.println(x.intValue()); System.out.println((Integer)x.compareTo(new Integer(4))); } } A. The program has a compile error because an Integer instance cannot be assigned to a Number variable. B. The program has a compile error because intValue is an abstract method in Number. C. The program has a compile error because x cannot be cast into Integer. D. The program has a compile error because the member access operator (.) is executed before the casting operator. E. The program compiles and runs fine

D

Analyze the following code: public class Test { public static void main(String[] args) { new B(); } } class A { int i = 7; public A() { setI(20); System.out.println("i from A is " + i); } public void setI(int i) { this.i = 2 * i; } } class B extends A { public B() { // System.out.println("i from B is " + i); } @Override public void setI(int i) { this.i = 3 * i; } } A. The constructor of class A is not called. B. The constructor of class A is called and it displays "i from A is 7". C. The constructor of class A is called and it displays "i from A is 40". D. The constructor of class A is called and it displays "i from A is 60".

D

Analyze the following code: public class Test { public static void main(String[] args) { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; } catch (Exception ex) { System.out.println("NumberFormatException"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } } } A. The program displays NumberFormatException. B. The program displays RuntimeException. C. The program displays NumberFormatException followed by RuntimeException. D. The program has a compile error

D

Analyze the following code: public class Test { public static void main(String[] args) { B b = new B(); b.m(5); System.out.println("i is " + b.i); } } class A { int i; public void m(int i) { this.i = i; } } class B extends A { public void m(String s) { } } A. The program has a compile error, because m is overridden with a different signature in B. B. The program has a compile error, because b.m(5) cannot be invoked since the method m(int) is hidden in B. C. The program has a runtime error on b.i, because i is not accessible from b. D. The method m is not overridden in B. B inherits the method m from A and defines an overloaded method m in B

D

Assume Calendar calendar = new GregorianCalendar(). __________ returns the week of the year. A. calendar.get(Calendar.MONTH) B. calendar.get(Calendar.MONTH_OF_YEAR) C. calendar.get(Calendar.WEEK_OF_MONTH) D. calendar.get(Calendar.WEEK_OF_YEAR)

D

Assume an employee can work for only one company. What is the best suitable relationship between Company and Employee? A. None B. Aggregation C. Inheritance D. Composition

D

Show the output of running the class Test in the following code lines: interface A { } class C { } class B extends D implements A { } public class Test { public static void main(String[] args) { B b = new B(); if (b instanceof A) System.out.println("b is an instance of A"); if (b instanceof C) System.out.println("b is an instance of C"); } } class D extends C { } A. Nothing. B. b is an instance of A. C. b is an instance of C. D. b is an instance of A followed by b is an instance of C

D

Suppose you enter 34.3 57.8 789, then press the ENTER key. Analyze the following code. Scanner input = new Scanner(System.in); double v1 = input.nextDouble(); double v2 = input.nextDouble(); String line = input.nextLine(); A. After the last statement is executed, line contains characters '7', '8', '9'. B. After the last statement is executed, line contains characters '7', '8', '9', '\n'. C. After the last statement is executed, line contains characters ' ', '7', '8', '9', '\n'. D. After the last statement is executed, line contains characters ' ', '7', '8', '9'

D

The Rational class in this chapter extends java.lang.Number and implements java.lang.Comparable. Analyze the following code. 1. public class Test { 2. public static void main(String[] args) { 3. Number[] numbers = {new Rational(1, 2), new Integer(4), new Double(5.6)}; 4. java.util.Arrays.sort(numbers); 5. } 6. } A. The program has a compile error because numbers is declared as Number[], so you cannot assign {new Rational(1, 2), new Integer(4), new Double(5.6)} to it. B. The program has a runtime error because numbers is declared as Number[], so you cannot assign {new Rational(1, 2), new Integer(4), new Double(5.6)} to it. C. The program has a compile error because numbers is declared as Number[], so you cannot pass it to Arrays.sort(Object[]). D. The program has a runtime error because the compareTo methods in Rational, Integer, and Double classes do not compare the value of one type with a value of another type

D

The output from the following code is __________. java.util.ArrayList<String> list = new java.util.ArrayList<String>(); list.add("New York"); java.util.ArrayList<String> list1 = (java.util.ArrayList<String>)(list.clone()); list.add("Atlanta"); list1.add("Dallas"); System.out.println(list1); A. [New York] B. [New York, Atlanta] C. [New York, Atlanta, Dallas] D. [New York, Dallas]

D

What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = new Object(); String d = (String)o; } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. ClassCastException E. No exception

D

What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = null; System.out.println(o); } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. No exception E. NullPointerException

D

What is displayed on the console when running the following program? public class Test { public static void main(String[] args) { try { System.out.println("Welcome to Java"); int i = 0; int y = 2/i; System.out.println("Welcome to Java"); } finally { System.out.println("End of the block"); } System.out.println("End of the block"); } } A. The program displays Welcome to Java three times followed by End of the block. B. The program displays Welcome to Java two times followed by End of the block. C. The program displays Welcome to Java two times followed by End of the block two times. D. The program displays Welcome to Java and End of the block, and then terminates because of an unhandled exception

D

Which of the following is a correct interface? A. interface A { void print() { }; } B. abstract interface A { print(); } C. abstract interface A { abstract void print() { };} D. interface A { void print();}

D

Which of the following statements is false? A. You can always pass an instance of a subclass to a parameter of its superclass type. This feature is known as polymorphism. B. The compiler finds a matching method according to parameter type, number of parameters, and order of the parameters at compile time. C. A method may be implemented in several subclasses. The Java Virtual Machine dynamically binds the implementation of the method at runtime. D. Dynamic binding can apply to static methods. E. Dynamic binding can apply to instance methods

D

______ is not a reference type. A. A class type B. An interface type C. An array type D. A primitive type

D

What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = null; System.out.println(o.toString()); } } A. ArithmeticException B. ArrayIndexOutOfBoundsException C. StringIndexOutOfBoundsException D. ClassCastException E. NullPointerException

E

What is the output of running class Test? public class Test { public static void main(String[] args) { new Circle9(); } } public abstract class GeometricObject { protected GeometricObject() { System.out.print("A"); } protected GeometricObject(String color, boolean filled) { System.out.print("B"); } } public class Circle9 extends GeometricObject { /** No-arg constructor */ public Circle9() { this(1.0); System.out.print("C"); } /** Construct circle with a specified radius */ public Circle9(double radius) { this(radius, "white", false); System.out.print("D"); } /** Construct a circle with specified radius, filled, and color */ public Circle9(double radius, String color, boolean filled) { super(color, filled); System.out.print("E"); } } A. ABCD B. BACD C. CBAE D. AEDC E. BEDC

E

Which of the following statements are true? A. If a file (e.g., c:\temp.txt) does not exist, new File("c:\\temp.txt") returns null. B. If a directory (e.g., c:\liang) does not exist, new File("c:\liang") returns null. C. If a file (e.g., c:\temp.txt) does not exist, new File("c:\\temp.txt") creates a new file named c:\temp.txt. D. If a directory (e.g., c:\liang) does not exist, new File("c:\liang") creates a new directory named c:\liang. E. None of the above

E

Which of the following statements regarding abstract methods is false? A. Abstract classes have constructors. B. A class that contains abstract methods must be abstract. C. It is possible to declare an abstract class that contains no abstract methods. D. An abstract method cannot be contained in a nonabstract class. E. A data field can be declared abstract

E

What are the reasons to create an instance of the File class? A. To determine whether the file exists. B. To obtain the properties of the file such as whether the file can be read, written, or is hidden. C. To rename the file. D. To delete the file. E. To read/write data from/to a file

A, B, C and D

Which of the following is poor design? A. A data field is derived from other data fields in the same class. B. A method must be invoked after/before invoking another method in the same class. C. A method is an instance method, but it does not reference any instance data fields or invoke instance methods. D. A parameter is passed from a constructor to initialize a static data field

A, B, C and D

Which of the following statements are true? A. The String class implements Comparable. B. The Date class implements Comparable. C. The Double class implements Comparable. D. The BigInteger class implements Comparable

A, B, C and D

An instance of _________ describes programming errors, such as bad casting, accessing an out-of-bounds array, and numeric errors.. A. RuntimeException B. Exception C. Error D. Throwable E. NumberFormatException

A

Which of the following is incorrect? A. A constructor may be static. B. A constructor may be private. C. A constructor may invoke a static method. D. A constructor may invoke an overloaded constructor. E. A constructor invokes its superclass no-arg constructor by default if a constructor does not invoke an overloaded constructor or its superclass?s constructor.

A

Which of the following statements are true? A. You use the keyword throws to declare exceptions in the method heading. B. A method may declare to throw multiple exceptions. C. To throw an exception, use the key word throw. D. If a checked exception occurs in a method, it must be either caught or declared to be thrown from the method

A, B, C and D

A method must declare to throw ________. A. unchecked exceptions B. checked exceptions C. Error D. RuntimeException

B

An instance of _________ describes the errors caused by your program and external circumstances. These errors can be caught and handled by your program. A. RuntimeException B. Exception C. Error D. Throwable E. NumberFormatException

B

Which of the following statements is false? A. If you compile an interface without errors, a .class file is created for the interface. B. If you compile a class without errors but with warnings, a .class file is created. C. If you compile a class with errors, a .class file is created for the class. D. If you compile an interface without errors, but with warnings, a .class file is created for the interface

C

A Java exception is an instance of __________. A. RuntimeException B. Exception C. Error D. Throwable E. NumberFormatException

D

Analyze the following code. Number[] numberArray = new Integer[2]; numberArray[0] = new Double(1.5); Which of the following statements is correct? A. You cannot use Number as a data type since it is an abstract class. B. Since each element of numberArray is of the Number type, you cannot assign an Integer object to it. C. Since each element of numberArray is of the Number type, you cannot assign a Double object to it. D. At runtime, new Integer[2] is assigned to numberArray. This makes each element of numberArray an Integer object. So you cannot assign a Double object to it

D

Analyze the following code. 1. public class Test { 2. public static void main(String[] args) { 3. Fruit[] fruits = {new Fruit(2), new Fruit(3), new Fruit(1)}; 4. java.util.Arrays.sort(fruits); 5. } 6. } class Fruit { private double weight; public Fruit(double weight) { this.weight = weight; } } A. The program has a compile error because the Fruit class does not have a no-arg constructor. B. The program has a runtime error on Line 3 because the Fruit class does not have a no-arg constructor. C. The program has a compile error on Line 4 because the Fruit class does not implement the java.lang.Comparable interface and the Fruit objects are not comparable. D. The program has a runtime error on Line 4 because the Fruit class does not implement the java.lang.Comparable interface and the Fruit objects are not comparable

D

Analyze the following code. public class Test { public static void main(String[] args) { java.util.Date x = new java.util.Date(); java.util.Date y = x.clone(); System.out.println(x = y); } } A. A java.util.Date object is not cloneable. B. x = y in System.out.println(x = y) causes a compile error because you cannot have an assignment statement inside a statement. C. x = y in System.out.println(x = y) causes a runtime error because you cannot have an assignment statement inside a statement. D. The program has a compile error because the return type of the clone() method is java.lang.Object

D

Assume Calendar calendar = new GregorianCalendar(). __________ returns the number of days in a month. A. calendar.get(Calendar.MONTH) B. calendar.get(Calendar.MONTH_OF_YEAR) C. calendar.get(Calendar.WEEK_OF_MONTH) D. calendar.get(Calendar.WEEK_OF_YEAR) E. calendar.getActualMaximum(Calendar.DAY_OF_MONTH)

E

The following code causes Java to throw _________. int number = Integer.MAX_VALUE + 1; A. RuntimeException B. Exception C. Error D. Throwable E. no exceptions

E