public void m1(){ int n = 5; m2( n ); System.out.println( n ); }

Transcription

1 Review The Dog class will be used as needed. public class Dog { private int x; public Dog(int h){ x = h; public void set(int n){ x = n; public int get(){ return x; public String tostring(){ return "woof"; Arguments and Parameters. Note. What we have called parameters are also called formal parameters and arguments are sometimes called actual parameters. 1. If the parameter is a primitive data type, then changing the parameter has no effect on the argument. What is displayed? 5 2. If the parameter is an object type, and the reference is not changed, then the method can change the object. What is displayed? 4 3. What is displayed? 3 public void m1(){ int n = 5; m2( n ); System.out.println( n ); public void m2( int k ){ k = 20; public void m3(){ Dog gone = new Dog( 3 ); m4( gone ); System.out.println( gone.get() ); public void m4( Dog gee ){ gee.set( 4 ); mutator method public void m5(){ Dog gone = new Dog( 3 ); m6( gone ); System.out.println( gone.get() ); n k gone gee gone public void m6( Dog gee ){ gee = new Dog( 5 ); gee.set( 6 ); gee

2 4. What is displayed? big 5. What is displayed? What is displayed? What is displayed? Yes? public void m5(){ String a = "big"; m6( a ); System.out.println( a ); public void m6( String str ){ str = str + " toe"; public void m5(){ int [] a = {7, 6, 5 ; m6( a ); for ( int x : a ) System.out.print( x + " "); public void m6( int [] b ){ b[0] = 11; public void m5(){ int [] a = {7, 6, 5 ; m6( a ); for ( int x : a ) System.out.print( x + " "); public void m6( int [] b ){ b[0] = 2; b = new int[2]; b[0] = 14; b[1] = 23; public void m7(){ String x = "Yes"; x = m8( x ); System.out.println( x ); public String m8( String str ){ str = str + "?"; return str; a str a b a b x str Generating Random Integers (int)( num * Math.random() ) + min where num = max - min Which expression generates a full range of valid indices of the array? C int [] a = new int[ some positive value ]; a) int index = (int)( (a.length-1)*math.random() ) + 1; b) int index = (int)( a.length*math.random() ) + 1; c) int index = (int)( a.length*math.random() ); d) int index = (int)( (a.length-1)*math.random() ); e) none of the above

3 oolean Expressions Order of Operations! highest precedence && middlest lowest!p!q DeMorgan s Laws!( p && q ) is equivalent to!p &&!q!( p q ) is equivalent to Truth Tables can be useful way of organizing all the combinations A expression True True True False False True False False D 9) Assume that a and b are integers. The boolean expression!(a <= b) && ( a*b > 0 ) will always evaluate to true given that a) a = b b) a > b c) a < b d) a > b and b > 0 e) a > b and b < 0 A 10) Given that a, b, and c are integers, consider the boolean expression (a < b)!( (c == a*b) && (c < a) ) Which of the following will guarantee that the expression is true? a) c < a is false b) c < a is true c) a < b is false d) c == a * b is true e) c == a * b is true, and c < a is true 11) If c and d are boolean variables, which one of the answer choices is NOT equivalent to the following expression? ( c && d )!= ( c d ) a) ( c &&!d ) (!c && d ) b) ( c d ) && (!c &&!d ) c) ( c d ) && (!c!d ) d) ( c d ) &&!( c && d ) e) c!= d 12) Specify the range of values of x and y that make this expression true. This is true for all values of x and y!( x > 10 && y > 20 )!(x <= 0 && y <= 5)

4 Enhanced For Loops. These are good for traversing an array or array list. Do NOT use if you need to compare adjacent elements or change the contents of an array or array list. for ( Data_Type_of_Each_Element var_name : collection ) { collection is an array, list, or array list The first time through the loop var_name is the element at index 0. The next time it is the element at index 1 and so on. D 13. What is displayed? int [] h = {9, 3, 7; for ( int v : h ) System.out.print( v + " " ); 14. Select the TRUE statement. a) This does not compile. b) This compiles but throws an index out of bounds exception. c) This displays d) This displays Write the missing code so the get method is called for each element of the array. Dog emma : cuties 16. Write the missing code so the get method is called for each element of the list. Dog emma : a int [] h = {1, 2, 0 ; for ( int v : h ) System.out.print( h[v] + " " ); Dog [] cuties = new Dog[ 5 ]; // Dog objects are assigned to the array for ( /* missing code */ ) System.out.println(emma.get()); List<Dog> a = new ArrayList<Dog>(); // Dog objects are added to the list for ( /* missing code */ ) System.out.println(emma.get()); Two Dimensional Arrays. A 2D array is an array of arrays. int [][] a = { { 5, 6, 7, { 4, 3, 2 ; a 17. What is the value of a.length? 18. What is the value of a[1].length? 19. What is the row index of a[ 1 ][ 0 ]? 20. What is the column index of a[ 0 ][ 1 ]? What is the contents of the array after the code is executed? int [][] a = { { 5, 6, 7, { 4, 3, 2 ; for ( int b = 0; b < a.length; b++ ){ for ( int c = 0; c < a.length; c++ ){ a[b][c] = a[c][b];

5 A 22. A WordSearch object consists of a 2D array of single characters. Complete the getdown method so that it returns a string that consists of the letters starting at (row, column) going down to and including (row+num-1, column). A precondition is that row and col are valid indices for the array. However, if num is too big and the end point is not a valid location in the array, then the method should return null. 23. Integer.MAX_VALUE is a: a) public class constant b) public instance constant c) public class method d) public instance method 24. If the array contains: what does the method return? -2 public class WordSearch{ private String [][] ltrs; public WordSearch(){ // creates a 2d array of single character strings // precondition: row and col are valid indices in the array public String getdown( int row, int col, int num ){ if ( row + num -1 >= ltrs.length ) return null; String x = ""; for ( int R = row; R < row + num; R++ ) x += ltrs[ R ][ col ]; return x; public int get5( int[][] a ){ int m = Integer.MAX_VALUE; for ( int r = 0; r < a.length; r++ ){ int b = 0; for ( int c = 0; c < a[r].length; c++ ) b += a[r][c]; if ( b < m ) m = b; return m; 25. If the array contains: what does the method return? public int get6( int[][] a ){ int m = Integer.MIN_VALUE; for ( int c = 0; c < a[0].length; c++ ){ int b = 0; for ( int r = 0; r < a.length; r++ ){ b += a[r][c]; 14 if ( b > m ) m = b; return m;

6 Enhanced For Loops and 2D Arrays. The important thing is to remember is that a 2D array is an array of arrays. int [][] a = { { 5, 6, 7, { 4, 3, 2 ; a For example, suppose we want to print the contents of the entire 2D array using enhanced for loops. The outer loop is used to traverse the array that a refers to. The inner loop traverses each of the arrays that are referenced by the outer loop. for ( x : a ) { int [] int for ( y : ) { System.out.print( y ); System.out.println(); 26. What is displayed? int [][] z = { { 9, 11, {3, 5, {7, 1 ; for ( int [] r : z ){ System.out.print( r.length + " " ); 27. Write the missing code so that the code prints int [][] z = { { 9, 11, 2, {4, 3, 5, {7, 1, 6 ; all the elements of the 2D array. for ( int k = 0; k < 3; k++ ){ for ( /* missing code */ ){ System.out.print( num + " " ); int num : z[ k ] System.out.println(); 28. Write the missing code so that the code prints all the elements of the 2D array. int i = 0; i < g.length; i Given an example of a 3 x 3 array that causes this method to return true. Your solution should NOT contain any duplicate values.* int [][] z = { { 9, 11, 2, {4, 3, 5, {7, 1, 6 ; for ( int [] g : z ){ for ( /* missing code */ ){ System.out.print( g[i] + " " ); System.out.println(); public static boolean check( int[][] a ){ for ( int c = 0; c < a[0].length; c++ ){ for ( int r = 1; r < a.length; r++ ){ if ( a[r-1][c] + 1!= a[r][c] ) return false; return true; The complete set of actual solutions does include duplicates. ut your solution should not. Each column should have increasing, sequential numbers x

7 E 30. Select the TRUE statement(s). a) This does not compile because of line 1 b) This does not compile because of line 2 c) This does not compile because of line 3 d) This does not compile because of line 4 e) Compiles but throws a run time exception Dog [][] d = new Dog[3][3]; for ( Dog [] a : d ){ for ( Dog b : a ){ System.out.println( b.get() ); A precondition of the getter method is that row >= 0 && row < a.length 31. What is the missing code so that the getter method correctly iterates through all the Dog objects in the specified row? public class DogChess{ private Dog [][] a = new Dog[8][8]; public DogChess(){ // some array elements are initialized // some elements are null Dog asta : a[ row ] public int getter(int row) { int sum = 0; for ( /* missing code */ ){ if ( asta!= null ) sum += asta.get(); return sum; Inheritance. Use the keyword extends to indicate that a class is a subclass of another A class should only extend another class if the subclass is a member of the super class (always). E.g. the Student class could be a subclass of the Human class because every Student is a Human. On the other hand, the Human class should NOT be a subclass of Student because not every Human is a Student. private instance variables and private methods in the super class cannot be accessed by the subclass. The absolute first thing a subclass constructor must do is call a constructor of its super class. Call the superclass s constructor like this: super( arguments ); If the superclass has a constructor with no parameters, then this constructor will be implicitly called unless you explicitly call a different constructor. is a very useful annotation, it is not testable and you will not see it on the exam. 32. What class s constructor is being called on line 4? 1 2 the Object class 3 4 public class Fish{ private int x; public Fish(int y){ super(); x = y;

8 public class House { private int distance; // from beach private int rooms; public House( int x ){ distance = x; rooms = // hidden public int rooms(){ return rooms; public int distance(){ return distance; 34. What does the code below display? oat b = new Yacht(); System.out.println( b.get() ); Yacht y = new Yacht(); System.out.println( y.get() ); Write the eachhouse class which is a subclass of House. All each House objects are right on the beach so their distance from the beach is zero. Override the rooms method so that it returns twice the number of rooms as a regular House. public class public class oat{ private int x; public oat(){ x = 6; eachhouse extends House{ public eachhouse(){ super( 0 ); public int rooms(){ return 2*super.rooms(); public int get(){ return 3*x; public class Yacht extends oat{ private int x; public Yacht(){ x = 11; 35. What does the code below display? public class Run { public static void main( String [] args ) { met( new Hockey() ); System.out.println(); met( new Sport() ); public static void met( Sport x ){ x.m1(); 36. Why must the method met be a static method? CA A because it is called from a static method public class Sport{ public void m1() { m2(); System.out.print("A"); public void m2() { System.out.print(""); public class Hockey extends Sport{ public void m2() { System.out.print("C"); public void m3() { System.out.print("D"); m1();

9 public class Mammal { public Mammal(){ System.out.print( "M" ); public class Human extends Mammal { public Human(){ System.out.print( "H" ); E A public void m1(){ System.out.print( "A" ); m2(); public void m2(){ System.out.print( "" ); The Mammal and Human classes compile and run. 37. Select the true statement. a) Does not compile. b) Compiles but throws a run-time exception. c) Displays: HA d) Displays: HAD e) none of the above 38. Select the true statement. a) Does not compile. b) Compiles but throws a run-time exception. c) Displays: HE d) Displays: MHE e) Displays: HME public void m2(){ System.out.print( "D" ); public void m3(){ super.m2(); System.out.print( "E" ); Mammal a = new Human(); a.m1(); Actually displays MHAD Mammal a = new Human(); a.m3(); m3 is not a Mammal method Recursion. Identify what the base case (i.e. under what circumstances does the method NOT call itself) Notice how each recursive call leads (eventually) to the base case. If it does not, then the method will generate a run-time exception. 39. What does r( 123 ) cause to be printed? public static void r( int x ){ if ( x <= 0 ) return; 123 r( x / 10 ); System.out.print( x % 10 ); 40. What does r( 456 ) cause to be printed? public static void r( int x ){ if ( x <= 0 ) return; 654 System.out.print( x % 10 ); r( x / 10 );

10 41. What does the following display? String [] a = { "k", "f", "i", "w", "s" ; System.out.println( m2( a, 0 ) ); "f" which is the least string 42. What does the following display? String [] b = {"gone","gown","gopher","got"; System.out.println( m2( b, 1 ) ); "gopher" which is the least string starting from index If s is 1234, what is printed? If s is abcdefgh, what is printed? public String m2( String [] a, int n ){ if ( n == a.length - 1 ) return a[ n ]; String x = a[n]; String y = m2( a, n+ 1 ); if ( x.compareto( y ) < 0 ) return x; else return y; public void m1( String s ){ if ( s.length() == 1 ){ System.out.print( s ); return; hgfedcba int x = s.length() / 2; m1( s.substring( x ) ); m1( s.substring( 0, x ) ); Overloading and Overriding. The term polymorphism refers to the situation where two methods have the same name but different behavior. Compile time polymorphism means two methods (with identical names) have different parameters and can be distinguished at compile time. Runtime polymorphism means the JVM determines which method to call based on the object reference. If two methods have the same name but different parameters types or different number of parameters, then the two methods are overloaded. If a superclass has a method and subclass writes a new method with the same header, then the method in the subclass overrides the method in the superclass. D 45. Select the TRUE statement a) The grunt method is overloaded. b) The grunt method is overridden. c) The grunt method is both overloaded and over ridden. d) There is a compiler error. Two methods, in the same class, cannot differ only by their return types. public class Ape { public void grunt(){ System.out.println( "RAWR" ); public String grunt(){ return "RAWR"; C 46. Given a method with this header: public int mummy( double x ) which of the following headers does NOT overload the method. All methods are in the same class. a) public int mummy( int a ) b) public int mummy( double x, double y ) c) public int mummy( double latte ) d) public int mummy()

11 Interfaces. An interface defines a set of behaviors (i.e. methods). If a class implements an interface, it must then support those behaviors. For example, because ArrayList implements the List interface, we know that it has a certain set of methods and acts in a certain way. LinkedList is a different class that also implements the List interface. This class also behaves like a List. The difference between ArrayList and LinkedList is in how they implement the List interface. One can be more efficient than the other depending on how the List is being used. Another example. If a class implements MouseListener then you know it must have five methods for responding to different mouse events (pressed, released, clicked, entered, exited). Here is an example of a simple interface. public interface Fun{ public void laugh(); public boolean smiling(); Here is a class that implements it. public class APCS implements Fun{ // instance variables // constructors and other methods public void laugh(){ System.out.println( "haha" ); public boolean smiling(){ if ( grade >= personal_goal ) return true; else return false; // instance variables Here are some details to remember. The methods in an interface are considered abstract because they have no body (though the keyword abstract is not used). An interface cannot have instance variables or constructors All methods in an interface are public The implementing class must implement all the methods of the interface.

12 Abstract Classes. An abstract class is used as a class to create subclasses from. For example, java has an abstract class called: RectangularShape To quote from the API RectangularShape is the base class for a number of Shape objects whose geometry is defined by a rectangular frame. Some of its methods are: getcenterx, getcentery, getwidth and getheight. RectangularShape is then extended by four subclasses: Arc2D, Ellipse2D, Rectangle2D, and RoundRectangle2D. It turns out that these four classes are also abstract but they have concrete subclasses. Here s an example. Imagine you are writing a game that is played on a checkerboard. There are many types of pieces on the board. One of them is a Mine (the thing that explodes when you step on it, not the thing that singing dwarves work in). A Mine object does not move (anyone know Stratego?). public abstract class Piece { private int row, col; public Piece( int r, int c ) { row = r; col = c; // attempt to move to this location // returns true if successful // otherwise returns false public abstract boolean move( int r, int c ); public class Mine extends Piece{ public Mine(int r, int c){ super( r, c ); public boolean move( int r, int c ){ return false; // other methods // returns true if this piece is adjacent to p // otherwise returns false public boolean nextto( Piece p ){ int diff1 = Math.abs( this.row - p.row ); int diff2 = Math.abs( this.col - p.col ); return diff1 <= 1 && diff2 <= 1; The Piece is class is abstract so that it can contain data and behaviors shared by closely related classes. ut it is abstract to force users to write subclasses of it. Here are some details to remember. An abstract class may have instance variables and/or constructors An abstract class may or may not have abstract methods (with the keyword abstract) An abstract class may have private methods. In general, think of an abstract class as a regular class except (1) you cannot instantiate an abstract method and (2) if the abstract class has abstract methods, a concrete subclass must implement those methods.

13 A E A 47. Select the TRUE statement(s) - there may be more than one. a) This code compiles. b) This code will not compile because an abstract class cannot have an instance variable. c) This code will not compile because an abstract class cannot have a constructor. d) This code will not compile because an abstract class cannot have a method that includes actual code. e) Regardless of whether it compiles or not, any concrete subclass must override/implement the cast method. 48. Given the below code, what is displayed? Art a = new Music(); a.metc(); 49. If the first line of above code was changed to Music a = new Music(); a) something different would be displayed. b) the same thing would be displayed. 50. Art b = new Music(); b.met(); Select the TRUE statement a) This does not compile because met is abstract b) It compiles and displays 51. Art c = new Art(); c.metc(); Select the TRUE statement a) The first line does not compile b) oth lines cause compiler errors. c) It compiles and displays C 52. Art d = new Music(); d.meta(); This displays a) ACAA b) ACCAA c) AAAC d) AAACC CC public abstract class Magic { private int a; public Magic( int b ){ a = b; public int get(){ return a; public abstract void cast(); public abstract class Art{ public void meta(){ System.out.print("A"); met(); metc(); public abstract void met(); public void metc(){ System.out.print("C"); public class Music extends Art{ public void meta(){ super.meta(); System.out.print("AA"); public void met(){ System.out.print(""); public void metc(){ System.out.print("CC");

14 53. If Fork is an abstract class then Fancy must be a concrete subclass of Fork. 54. Fork may be an interface. True True False False Fork [] x = new Fork[2]; x[0] = new Fancy(); x[1] = new Plain(); 55. Plain may be an interface. True False 56. Fancy may be an abstract class. True False 57. Select the TRUE statement. a) If this code compiles then the Mascot interface must have exactly two methods. b) If this code compiles then the Mascot interface may have one or two methods. c) This class cannot compile because neither method contains any implementing code. public class Goat implements Mascot{ public void m1() { public void m2() { Miscellaneous Questions/Topics. A 58. In the space below show how to call this method from some client code in another class. Set the rows to 2 and the cols to 3. int[][] a = Num1.get(2,3); 59. What does the array contain? Write it so it is obvious what the row and column is for each value If the array contains the following values: then the method a) returns 3 b) returns 1 c) returns 4 d) returns 2 e) throws an index out of bound exception public class Num1{ public static int[][] get( int rows, int cols ){ int [][] a = new int[ rows ][ cols ]; for ( int r = 0; r < a.length; r++ ){ for ( int c = 0; c < a[r].length; c++ ) a[r][c] = r + rows*c; return a; public int get2( int[][] a ){ int i = 0; int num = a.length * a[0].length; while ( i < num ){ int k = i / a[0].length; int j = i % a[0].length; if ( a[ k ][ j ] % 3 == 0 ) return i; i++; return i;

15 E 61. Which of the following statements must be true when the loop exits? a) (width > 0) && (height / width > 5) b) (width == 0) && (height / width > 5) c) (width <= 0) && (height / width <= 5) d) (width == 0) (height / width <= 5) e) (width <= 0) (height / width <= 5) 62. If the array contains the following: { 5, 8, 2, 6, 9, 1, 4 then what does this method return? Consider the following instance variable and method. int width, height; // width is assigned some positive value // height is some value greater than width while((width > 0) && (height / width > 5)){ height -= width; width -= 2; public int get3( int [] a ){ int m = a[0]; for ( int i = 1; i < a.length; i++ ){ if ( a[i] > a[i-1] ) m = a[i]; return m; Common mistake for finding min or max private double[] list; public int getit(double value) { int k = 0; while(k < list.length && list[k]!= value) k++; if(k < list.length) return k; else return -1; Which of the following best describes what is returned by this method? C a) The number of times that value occurs in list, or -1 if all items in the list equal value. b) The number of items in list that are not equal to value, or -1 if value is not in list. c) The index of the first occurrence of value in list, or -1 if value is not in list d) The index of the last occurrence of value in list, or -1 if value is not in list e) The index of the first item in list that is not equal to value, or -1 if value is not in list D 64. This method returns true if a) the array elements are in decreasing order b) the array elements are in increasing order c) the array elements are in non-decreasing order d) the array elements are in non-increasing order public boolean get4( int [] a ){ for ( int i = 1; i < a.length; i++ ){ if ( a[i-1] < a[i] ) return false; return true;

16 65. The following code compiles, runs, and displays no. Explain. Mathematical operations with doubles can result in small, unavoidable errors known as floating-point errors. double x = 1.7; double y = 1.9; if ( x + y == 3.6 ) System.out.println( "yes" ); else System.out.println( "no" ); 66. What is displayed? public static void main(string[] args) { int [] b = { 8, 4, 6, 9, 5 ; m7( b ); for ( int i : b ) System.out.print( i + " " ); public static void m7( int [] a ){ for ( int i = 0; i < a.length-1; i++ ){ int num = i+1; for ( int j = i; j < a.length; j++ ){ if ( a[j] < a[num] ) num = j; if ( a[i] > a[num] ){ int temp = a[i]; a[i] = a[num]; a[num] = temp; D A 67. The code segment is intended to sum the first 10 positive odd integers. Which of the following best describes the error, if any, in this code. a) The segment works as intended. b) The segment sums the first 9 odd integers c) The segment sums the first 20 odd integers d) The segment leaves out the first odd integer and includes the eleventh odd integer in the sum. e) The variable sum is incorrectly initialized. The segment would work as intended if sum were initialized to Select the TRUE statement. a) 23, 11 b) 11, 23 c) 23, 23 d) 11, 11 sum = 0; for(int k = 1; k <= 10; k++){ sum += 2*k + 1; public static void main(string[] args) { int x = 23; int y = 11; m7( x, y ); System.out.println( x + ", " + y ); public static void m7( int a, int b ){ int temp = a; a = b; b = temp;

17 69. What is printed? List<String> z = new ArrayList<String>(); z.add("f"); I S T z.add("i"); z.add("r"); z.add("s"); z.add("t"); z.remove(0); z.remove(1); for ( String s : z ) System.out.println( s ); 70. What is displayed? public static void main(string[] args) { int [] a = { 1, 2, 3 ; int [] b = { 4, 5, 6 ; m1( a ); m2( b ); System.out.println( a[0] + ", " + b[0] ); 1, 8 public static void m1( int [] a ){ a = new int[3]; a[0] = 8; public static void m2( int [] b ){ b[0] = 8; Write 43 in base Write 99 in hexadecimal. 73. Write in base Write 2EA 16 in base 10. E 75. The expression on the right can be rewritten as a) x == 0 y <= 0 b) x == 0 && y <= 0 c) x == 0 y < 0 d) x == 0 && y < 0 e) x!= 0 && y > The expression on the right can be rewritten as a) true (because this is always true) b) false (because this is always false) c) n > 50 n <= 60 d) n >= 50 && n < 60 e) n > 50 && n <= 60!( x!= 0 y > 0 )!( n <= 50 n > 60 )

18 D 77. m1 and m2 must each return a boolean. True False 78. If m1 returns true, then method m2 will not be called. True False 79. If m1 returns false, then method m2 will not be called. True False 80. Select the TRUE statement(s). a) If the user enters YES, then A is displayed. b) If the user enters yes, then A is displayed. c) This code will not compile because you cannot use == with two objects. d) This code compiles but will always display, no matter what the user enters. if ( m1() && m2() ) // code A else // code String s1 = "yes"; String s2; /* Code that asks the user to enter a word and assigns it to s2. */ if ( s1 == s2 ) System.out.println( "A" ); else System.out.println( "" ); D 81. Select the TRUE statement a) All three expressions may sometimes throw a run-time exception. b) All three expressions always throw a runtime exception. c) Only expression (A) sometimes throw a runtime exception. Expressions () and (C) never throw a run-time exception. d) Expressions (A) and () sometimes throw run-time exceptions. Expression (C) never throws a run-time exception. e) None of the three expressions ever throw a run-time exception. Assume that all variables have been declared and initialized. n may or may not be a valid index for the array. (A) a[n] > 0 && n < a.length && n >= 0 () n < a.length && a[n] > 0 && n >= 0 (C) n < a.length && n >= 0 && a[n] > 0 Hint. This question is about short-circuit evaluation. 82. What is displayed? public static void main(string[] args) { int [] a = { 1, 2, 3 ; m1( a ); for ( int num : a ) System.out.print( num + " " ); public static void m1( int [] a ){ int [] b = new int[ a.length ]; for ( int k = 0; k < b.length; k++ ) b[k] = 10*a[k]; a = b;

19 83. What does this code print? for ( int k = 1; k < 5; k++ ){ for ( int i = 1; i < k; i++ ){ System.out.print( k + " " ); System.out.println(); C C C Assume the code to the right compiles and runs. 84. Select the True statement. a) a must be an instance variable. b) a must be a class variable. c) a may be an instance variable or a class variable d) none of the above 85. Select the True statement. a) b must be an instance variable. b) b must be a class variable. c) b may be an instance variable or a class variable d) none of the above 86. When this is run, the first two strings to be printed are: java.lang.object@168ca82 java.lang.object@8bf035 The next two strings are: a) something that looks like the first two strings b) hey woof 87. This code demonstrates the concept of: a) overloading / compile time polymorphism b) overriding / runtime polymorphism c) neither of the above 88. Select the TRUE statement. a) x must be an instance variable b) x must be a class variable c) x may be an instance or class variable. 89. Select the TRUE statement. a) y must be an instance variable b) y must be a class variable c) y may be an instance or class variable. 90. Select the TRUE statement. a) methodz must be an instance method b) methodz must be a class method c) methodz may be an instance or class method. 91. Select the TRUE statement. a) methodzzzz must be an instance method b) methodzzzz must be a class method c) methodzzzz may be an instance or class method. public class Dog { // instance variables // constructors and methods public static int method1(){ return a; public int method2() return b; Object [] a = new Object[4]; a[0] = new Object(); a[1] = new Object(); a[2] = "hey"; a[3] = new Dog( 5 ); for ( Object x : a ) System.out.println( x ); public void methoda() { System.out.println( x ); public static void method() { System.out.println( y ); public void methodc() { methodz(); public static void methodd() { methodzzzz();

20 92. What is displayed? public static void main( String [] args ) { Dog a = new Dog( 5 ); dohtem( a ); System.out.println( a.get() ); 11 public static void dohtem( Dog e ){ Dog y = e; y.set( 11 ); 93. What is displayed? public static void main( String [] args ) { Dog a = new Dog( 5 ); dohtem( a ); System.out.println( a.get() ); 5 A A A 94. This method returns a) 3 b) 3.0 c) This displays a) 9H b) 45H 96. This displays a) T9 b) T c has a value of a) 4.0 b) c has a value of a) 4.0 b) c has a value of a) 4.0 b) 4.9 public static void dohtem( Dog e ){ e = new Dog( 14 ); public double mm(){ return 38 / 10; int a = 4; int b = 5; System.out.println( a + b + "H" ); int a = 4; int b = 5; System.out.println( "T" + a + b ); int a = 49; int b = 10; double c = a/b; int a = 49; int b = 10; double c = 1.0*a/b; int a = 49; int b = 10; double c = a/b*1.0;