Tarrin Thomas
SD 1420
Unit 9 Assignment
· Which of the following statements converts a double value d into a string s? · s = new Double(d).stringOf(); · s = String.stringOf(d); · s = (new Double(d)).toString(); · s = (Double.valueOf(s)).toString(); The answer is D
· Assume Calendar calendar = new GregorianCalendar(). Which of the following statements will return the number of days in a month? · calendar.getActualMaximum(Calendar.DAY_OF_MONTH) · calendar.get(Calendar.MONTH_OF_YEAR) · calendar.get(Calendar.WEEK_OF_MONTH) · calendar.get(Calendar.WEEK_OF_YEAR) · calendar.get(Calendar.MONTH) The answer is E
· Assume Calendar calendar = new GregorianCalendar(). Which of the following statements will return the week of the year? · calendar.get(Calendar.MONTH_OF_YEAR) · calendar.get(Calendar.WEEK_OF_YEAR) · calendar.get(Calendar.WEEK_OF_MONTH) · calendar.get(Calendar.MONTH) The answer is B
· What will be the output of running the class Test with the following code lines? interface A {
}

class C {
}

class B extends D implements A {
}

public class Test extends Thread { 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 {
}

· b is an instance of A followed by b is an instance of C. · b is an instance of C. · There will be no output. · b is an instance of A. The answer is A
· What is the output of the following code?

public class Test { public static void main(String[] args) { java.math.BigInteger x = new java.math.BigInteger("3"); java.math.BigInteger y = new java.math.BigInteger("7"); x.add(y); System.out.println(x); }
}

· 3 · 4 · 11 · 10 The answer is A

· Assume Calendar calendar = new GregorianCalendar(). Which of the following statements will return the month of the year? · calendar.get(Calendar.MONTH_OF_YEAR) · calendar.get(Calendar.MONTH) · calendar.get(Calendar.WEEK_OF_YEAR) · calendar.get(Calendar.WEEK_OF_MONTH) The answer is A
· Analyze the following code:

Number[] numberArray = new Integer[2]; numberArray[0] = new Double(1.5);

What will happen when the code is executed? · At runtime, new Integer[2] is assigned to numberArray. This makes each element of numberArray an Integer object. Therefore, you cannot assign a Double object to it. · You cannot use Number as a data type because it is an abstract class. · Each element of numberArray is of the Number type; therefore, you cannot assign a Double object to it. · Each element of numberArray is of the Number type; therefore, you cannot assign an Integer object to it. The answer is A
· Which of the following statements will convert a string s into a double value d? · d = Double.parseDouble(s); · d = Double.valueOf(s).doubleValue(); · d = (new Double(s)).doubleValue(); · All of the above The answer is D
· Which of the following declares an abstract method in an abstract Java class? · public abstract method(); · public abstract void method() {} · public void abstract Method(); · public abstract void method(); · public void method() {} The answer is A

· Analyze the following code:

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))); }
}

What will happen when the code is executed? · The program has a syntax error because intValue is an abstract method in Number. · The program has a syntax error because x does not have the compareTo method. · The program has a syntax error because an Integer instance cannot be assigned to a Number variable. · The program compiles and runs fine. The answer is B
· Analyze the following code:

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))); }
}

What will happen when the code is executed? · The program has a syntax error because x cannot be cast into Integer. · The program has a syntax error because an Integer instance cannot be assigned to a Number variable. · The program compiles and runs fine. · The program has a syntax error because the member access operator (.) is executed before the casting operator. · The program has a syntax error because intValue is an abstract method in Number. The answer is D

· Analyze the following code: Number numberRef = new Integer(0); Double doubleRef = (Double)numberRef; What will happen when the code is executed? · A runtime class casting exception occurs because numberRef cannot be cast as a Double. · You can convert an int to double; therefore, you can cast an Integer instance to a Double instance. · There is no such class named Integer. You should use the class Int. · The compiler detects that numberRef is not an instance of Double. · The program runs fine because Integer is a subclass of Double. The answer is A
· Which of the following statements correctly declares an interface? · abstract interface A { abstract void print() { };} · interface A { void print() { }; } · abstract interface A { print(); } · interface A { void print();} The answer is C
· What is the output of Integer.parseInt("10", 2)? · 2; · Invalid statement; · 10; · 1; The answer is B
· Which of the following class definitions defines a legal abstract class? · public class abstract A { abstract void unfinished(); } · abstract class A { abstract void unfinished(); } · class A { abstract void unfinished(); } · class A { abstract void unfinished() { } }

· Analyze the following code: 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. } What will happen when the code is executed? · The program has a syntax error on Line 6 because Calendar[1] is not of a GregorianCalendar type. · The program has a syntax error on Line 5 because java.util.Calendar is an abstract class. · The program has a syntax error on Line 4 because java.util.Calendar is an abstract class. The answer is A
· __________ is a special form of association that represents an ownership relationship between two objects. · Inheritance · Aggregation · Association · Composition The answer is 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. } What will happen when the code is executed? · The program has a syntax error because numbers is declared as Number[]; therefore, you cannot pass it to Arrays.sort(Object[]). · The program has a syntax error because numbers is declared as Number[]; therefore, you cannot assign {new Rational(1, 2), new Integer(4), new Double(5.6)} to it. · 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. · The program has a runtime error because number is declared as Number[]; therefore, you cannot assign {new Rational(1, 2), new Integer(4), new Double(5.6)} to it. The answer is C
· __________ array is actually an array in which each element is another array. · One · Two · Three · Multidimensional The answer is D
· Which of the following statements is incorrect about constructors? · A constructor may invoke a static method. · A constructor may be private. · A constructor may invoke an overloaded constructor. · 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 constructor may be static. The answer is E