Sample Solution A10 R6.2 R6.3 R6.5. for (i = 10; i >= 0; i++)... never ends. for (i = -10; i <= 10; i = i + 3)... 6 times

Transcription

1 Sample Solution A10 R R6.3 for (i = 10; i >= 0; i++)... never ends for (i = -10; i <= 10; i = i + 3)... 6 times R6.5 int n = 1; double x = 0; double s = 1; /* dirty trick to make sure the loop passes the first time while (s > 0.01) s = 1.0 / (n * n); x = x + s; n++;

2 R6.7 Solution 1: boolean done = false; while (!done) String bridge = in.next(); if (bridge.equalsignorecase("q")) done = true; else Process data Integer length = in.nextinteger(); if (length == 0) done = true; else Process and print data of Bridge Solution 2: public void processinput(scanner in) while (true) String brigde = in.next(); if (bridge.equalsignorecase("q")) return; Process data Integer length = in.nextinteger(); if (length == 0) return; Process and print data of Bridge Solution 3: public void processinput(scanner in) while (true) String brigde = in.next(); if (bridge.equalsignorecase("q")) break; Process data Integer length = in.nextinteger(); if (length == 0) break; Process and print data of Bridge

3 The clearest approach is the one. R6.10 Solution: import java.util.random; This class models a card drawing that, when cast, lands on a random 52 card. public class Card private Random generator; private int cards; Constructs a playing card with a given number of c the number of cards, e.g., 52 for a normal playing card public Card(int c) cards = c; generator = new Random(); Simulates a playing of the card of the playing public int cast() return 1 + generator.nextint(cards); For avoid repetitions is necessary verify if a card already was playing.

4 P6.2 import java.util.scanner; public class P2 public static void main(string[] args) Integer odd=new Integer(0); Integer even=new Integer(0); Integer temp=new Integer(0); Integer control = new Integer(0); System.out.println("Please, insert credit card number (8 digits): "); Scanner in = new Scanner(System.in); String ccn = in.next(); control=ccn.charat(ccn.length()-1)-48; for(int i=ccn.length()-1;i>=0;i--) if (i%2!=0) even+=(ccn.charat(i)-48); else temp=(ccn.charat(i)-48)*2; for(int j=temp.tostring().length()-1;j>=0;j--) odd+=(temp.tostring().charat(j)-48); temp=odd+even; if(temp%10==0) System.out.println("Number is valid!!!"); else System.out.println("Number is invalid!!!"); System.out.println("Control number would be " + Math.abs((controltemp%10))%10);

5 P6.5 public class PowerGenerator private double afactor; private double power; Constructs a power afactor the number that will be multiplied by itself public PowerGenerator(double afactor) this.afactor=afactor; this.power=0; Computes the next power. public double nextpower() return Math.pow(aFactor, power++); public static void main(string Args[]) PowerGenerator PG = new PowerGenerator(10); for(int i=1;i<=12;i++) System.out.println(PG.nextPower());

6 P6.6 FibonacciGenerator.java Class used to generate a Fibonacci number with a given input public class FibonacciGenerator Construct a FibonacciGenerator object to generate a Fibonacci number public FibonacciGenerator() fold1 = 1; fold2 = 1; fnew = 1; Method used to calculate a fibonacci fnew the fibonacci number public int nextnumber() fnew = fold1 + fold2; fold2 = fold1; fold1 = fnew; return fnew; private int fold1; private int fold2; private int fnew; ExP6_6.java import javax.swing.joptionpane;

7 Test driver class for FibonacciGenerator class public class ExP6_6 public static void main(string[] args) String input = JOptionPane.showInputDialog( "Enter n:"); int n = Integer.parseInt(input); FibonacciGenerator fg = new FibonacciGenerator(); int next = 0; if (n <= 2) next = 1; else for (int i = 3; i <= n; i++) next = fg.nextnumber(); System.out.println("fib(" + n + ") = " + next); System.exit(0);

8 P6.8 Complete the following class in your solution: This class generates all the factors of a number. public class FactorGenerator // TODO: instance fields Creates a FactorGenerator object used to determine the factor of an input anum is the input value public FactorGenerator(int anum) // TODO Determine whether or not there are more true if there are more factors public boolean hasmorefactors() // TODO Calculate the next factor of a factor the next factor public int nextfactor() 6 // TODO Use the following class as your tester class: public class FactorGeneratorTester public static void main(string[] args) FactorGenerator generator = new FactorGenerator(2 * 2 * 3 * 5); System.out.println(generator.hasMoreFactors()); System.out.println("Expected: true"); System.out.println(generator.nextFactor());

9 System.out.println("Expected: 2"); System.out.println(generator.hasMoreFactors()); System.out.println("Expected: true"); System.out.println(generator.nextFactor()); System.out.println("Expected: 2"); System.out.println(generator.hasMoreFactors()); System.out.println("Expected: true"); System.out.println(generator.nextFactor()); System.out.println("Expected: 3"); System.out.println(generator.hasMoreFactors()); System.out.println("Expected: true"); System.out.println(generator.nextFactor()); System.out.println("Expected: 5"); System.out.println(generator.hasMoreFactors()); System.out.println("Expected: false");

10 P6.9 public class PowerGenerator private double afactor; private double power; Constructs a power afactor the number that will be multiplied by itself public PowerGenerator(double afactor) this.afactor=afactor; this.power=0; Computes the next power. public double nextpower() return Math.pow(aFactor, power++); public static void main(string Args[]) PowerGenerator PG = new PowerGenerator(10); for(int i=1;i<=12;i++) System.out.println(PG.nextPower());

11 P6.10 RootApproximator.java This class implements the Newton-Raphson method to approximate the root of an input value public class RootApproximator Creates a RootApproximator object used to approximate the root answer of a ana the input an the root number extracted public RootApproximator(double ana, int an) a = ana; n = an; xold = 1; xnew = a; Method used to calculate the next root the next guess number public double nextguess() xold = xnew; xnew = xold * (1-1.0 / n) + a / (n * Math.pow(xold, n - 1)); return xnew; Determine if there are more true we are close enough to the answer public boolean hasmoreguesses() final double EPS = ; return (Math.abs(xnew - xold) > EPS);

12 private double a; private int n; private double xold; private double xnew; ExP6_10.java import javax.swing.joptionpane; Test class for RootApproximator class public class ExP6_10 public static void main(string[] args) String input = JOptionPane.showInputDialog( "Please enter a number:"); double a = Double.parseDouble(input); input = JOptionPane.showInputDialog( "Extract which root?"); int n = Integer.parseInt(input); RootApproximator r = new RootApproximator(a, n); while (r.hasmoreguesses()) System.out.println(r.nextGuess()); System.exit(0);

13 P6.11 import java.util.scanner; public class RootAproximator private double a; private double epsilon; private double n; public RootAproximator(double a, double n, double epsilon) this.a =a; this.epsilon=epsilon; this.n = n; public double getroot() double value=a/n, guess=0.0; if (n!=2) do guess=value; value = guess - (Math.pow(guess,n)-a)/((n-1)*Math.pow(guess, n-1)); while(math.abs(value-guess)>=epsilon); else do guess=value; value = (guess + a/guess)/2; while(math.abs(value-guess)>=epsilon); return value; public static void main(string[] args) System.out.println("Please, insert a: "); Scanner in = new Scanner(System.in); double a = in.nextdouble(); System.out.println("Please, insert n: "); double n = in.nextdouble(); RootAproximator RA = new RootAproximator(a,n,0.0001); System.out.println(RA.getRoot());

14 P6.12 public class ExpApproximator private double epsilon=0.0001; private double x; public ExpApproximator(double x,double epsilon)this.x=x;this.epsilon=epsilon;; public double getvalue() double ex=0,term=1.0,n=1; int i=0; do ex=ex+term; i++; n=1; for(int j=1;j<=i;j++) n*=j; term = Math.pow(x, i) / n; while (term>epsilon); return ex; public static void main(string[] args) ExpApproximator EA = new ExpApproximator(1, ); System.out.println(EA.getValue());

15 P6.19 import java.awt.graphics; import java.awt.graphics2d; import java.awt.geom.line2d; import java.awt.geom.point2d; import javax.swing.jcomponent; import javax.swing.jframe; public class SpiralComponent extends JComponent * private static final long serialversionuid = 1L; public void paintcomponent(graphics g) Graphics2D g2 = (Graphics2D) g; final int INITIAL_SIZE = 10; int size = Math.min(getWidth(), getheight()); SpiralGenerator gen = new SpiralGenerator(INITIAL_SIZE,new Point2D.Double(size / 2, size / 2)); while (true) Line2D.Double segment = gen.nextsegment(); if (!segment.intersects(getbounds())) return; g2.draw(segment); public static void main(string[] args) JFrame frame = new JFrame(); final int FRAME_WIDTH = 400; final int FRAME_HEIGHT = 400; frame.setsize(frame_width, FRAME_HEIGHT); frame.settitle("spiralviewer");

16 frame.setdefaultcloseoperation(jframe.exit_on_close); SpiralComponent component = new SpiralComponent(); frame.add(component); frame.setvisible(true); import java.awt.geom.point2d; import java.awt.geom.line2d; public class SpiralGenerator Creates a spiral initialsize the size of the first (shortest) segment of the spiral, in start the starting point of the spiral public SpiralGenerator(double initialsize, Point2D.Double start) init = start; size = initialsize; Returns the next segment of the the next segment public Line2D.Double nextsegment() Line2D.Double test = new Line2D.Double(0.0,0.0,0.0,0.0); return test; // private implementation private double size; private Point2D.Double init;