Study the solution to Programming project 10.9 below.

Note that the slope (coefficient b) does not turn negative when the slider is moved to a negative number.

1. Can you fix this problem with the code? (50 points)

2. Describe accurately and in detail what the overall effect on the graph of the equation is?(50 points)

//******************************************************************** // Equation.java Authors: Lewis/Loftus // // Solution to Programming Project 10.9 //******************************************************************** public class Equation { private int a, b, c; public final String SQUARED = "\u00B2"; //------------------------------------------------------------------ // Sets up the default coeficients of this equation: // a*x^2 + b*x + c //------------------------------------------------------------------ public Equation() { a = b = c = 0; } //------------------------------------------------------------------ // Sets up the coeficients of this equation as specified. //------------------------------------------------------------------ public Equation (int aValue, int bValue, int cValue) { a = aValue; b = bValue; c = cValue; } //------------------------------------------------------------------ // Computes the current value of this equation. //------------------------------------------------------------------ public double computeValue(double x) { return a*x*x + b*x + c; } //------------------------------------------------------------------ // Returns a string representation of this equation. //------------------------------------------------------------------ public String toString() { StringBuffer equation = new StringBuffer(); if (a==0 && b==0 && c==0) equation.append("0"); else { if (a != 0) { if (a==-1) equation.append("-"); else if (a!=1) equation.append(a); equation.append( "x" + SQUARED); } if (b != 0) { if (b < 0) { if (a==0) equation.append("-"); else equation.append(" - "); b = -b; } else equation.append(" + "); if (b!=1 && b!= -1) equation.append(b); equation.append("x"); } if (c != 0) { if (c < 0) { if (a!=0 || b!=0) equation.append(" - "); else equation.append("-"); c = c; } else equation.append(" + "); equation.append(c); } } // erase leading + if (equation.length() > 2) { char ch = equation.charAt(1); if (ch=='+') { equation.deleteCharAt(0); equation.deleteCharAt(0); } } return equation.toString(); } }

//******************************************************************** // EquationGraph.java Author: Lewis/Loftus // // Solution to Programming Project 10.9 //******************************************************************** import javax.swing.*; public class EquationGraph { //----------------------------------------------------------------- // Creates and presents the program frame. //----------------------------------------------------------------- public static void main(String[] args) { JFrame frame = new JFrame("Equation Graph"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(new EquationGraphPanel()); frame.pack(); frame.setVisible(true); } }

//******************************************************************** // EquationGraphPanel.java Authors: Lewis/Loftus // // Solution to Programming Project 10.9 //******************************************************************** import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.border.LineBorder; public class EquationGraphPanel extends JPanel { private JSlider aSlider; private JSlider bSlider; private JSlider cSlider; private EquationViewportPanel display; private JLabel equationLabel; private final String EQUATION_SUBSTRING = "Graph of equation y = "; private final int MIN_VALUE = -5; private final int MAX_VALUE = 5; private final int INIT_VALUE = 0; private final int TICK_SPACING = 5; private final int MINOR_TICK_SPACING = 1; //----------------------------------------------------------------- // Sets up the panel. //----------------------------------------------------------------- public EquationGraphPanel() { setLayout(new BorderLayout()); add(getSliderPanel(), BorderLayout.WEST); display = new EquationViewportPanel(); add(display, BorderLayout.CENTER); equationLabel = new JLabel(EQUATION_SUBSTRING + 0); equationLabel.setHorizontalAlignment(SwingConstants.CENTER); equationLabel.setFont(new Font("Dialog", Font.BOLD, 16)); add(equationLabel, BorderLayout.NORTH); } //----------------------------------------------------------------- // Creates the sliders and slider panel. //------------------------------------------------------------- private JPanel getSliderPanel() { SliderMouseListener changed = new SliderMouseListener(); aSlider = new JSlider(JSlider.HORIZONTAL, MIN_VALUE, MAX_VALUE, INIT_VALUE); aSlider.setPaintTicks(true); aSlider.setPaintLabels(true); aSlider.setMajorTickSpacing(TICK_SPACING); aSlider.setMinorTickSpacing(MINOR_TICK_SPACING); aSlider.setSnapToTicks(true); aSlider.addMouseListener(changed); bSlider = new JSlider(JSlider.HORIZONTAL, MIN_VALUE, MAX_VALUE, INIT_VALUE); bSlider.setPaintTicks(true); bSlider.setPaintLabels(true); bSlider.setMajorTickSpacing(TICK_SPACING); bSlider.setMinorTickSpacing(MINOR_TICK_SPACING); bSlider.setSnapToTicks(true); bSlider.addMouseListener(changed); cSlider = new JSlider(JSlider.HORIZONTAL, MIN_VALUE, MAX_VALUE, INIT_VALUE); cSlider.setPaintTicks(true); cSlider.setPaintLabels(true); cSlider.setMajorTickSpacing(TICK_SPACING); cSlider.setMinorTickSpacing(MINOR_TICK_SPACING); cSlider.setSnapToTicks(true); cSlider.addMouseListener(changed); JPanel aPanel = new JPanel(); aPanel.setLayout(new BoxLayout(aPanel, BoxLayout.Y_AXIS)); aPanel.setBorder(new LineBorder(Color.black)); aPanel.add(new JLabel("value of 'a'")); aPanel.add(aSlider); JPanel bPanel = new JPanel(); bPanel.setLayout(new BoxLayout(bPanel, BoxLayout.Y_AXIS)); bPanel.setBorder(new LineBorder(Color.black)); bPanel.add(new JLabel("value of 'b'")); bPanel.add(bSlider); JPanel cPanel = new JPanel(); cPanel.setLayout(new BoxLayout(cPanel, BoxLayout.Y_AXIS)); cPanel.setBorder(new LineBorder(Color.black)); cPanel.add(new JLabel("value of 'c'")); cPanel.add(cSlider); JPanel sliderPanel = new JPanel(); sliderPanel.setLayout(new BoxLayout(sliderPanel, BoxLayout.Y_AXIS)); JLabel title = new JLabel("ax\u00B2 + bx + c"); title.setFont(new Font("Dialog", Font.BOLD, 16)); title.setHorizontalAlignment(SwingConstants.CENTER); sliderPanel.add(title); sliderPanel.add(new JLabel("Select values for each coefficient:")); sliderPanel.add(Box.createVerticalGlue()); sliderPanel.add(aPanel); sliderPanel.add(Box.createVerticalGlue()); sliderPanel.add(bPanel); sliderPanel.add(Box.createVerticalGlue()); sliderPanel.add(cPanel); return sliderPanel; } //----------------------------------------------------------------- // Update and equation label. //------------------------------------------------------------- private void updateEquationLabel (Equation equation) { equationLabel.setText (EQUATION_SUBSTRING + equation.toString()); } //******************************************************************** // Represents the mouse listener class for the sliders. //******************************************************************** private class SliderMouseListener extends MouseAdapter { //----------------------------------------------------------------- // Redraws the graph. //----------------------------------------------------------------- public void mouseReleased(MouseEvent event) { Equation equation = new Equation(aSlider.getValue(), bSlider.getValue(), cSlider.getValue()); display.setEquation(equation); updateEquationLabel(equation); repaint(); } } }

//******************************************************************** // EquationViewportPanel.java Authors: Lewis/Loftus // // Solution to Programming Project 10.9 //******************************************************************** import java.awt.*; import javax.swing.JPanel; import javax.swing.border.LineBorder; public class EquationViewportPanel extends JPanel { private final int X_MIN = -10, Y_MIN = -10, X_MAX = 10, Y_MAX = 10; private final int REAL_WORLD_WIDTH = X_MAX - X_MIN; private final int REAL_WORLD_HEIGHT = Y_MAX - Y_MIN; private final double TICK_LENGTH = 0.2; private Equation equation; //----------------------------------------------------------------- // Constructor: Sets up this panel. //----------------------------------------------------------------- public EquationViewportPanel() { equation = new Equation(); setBorder(new LineBorder(Color.black, 4)); setPreferredSize(new Dimension(500, 500)); } //----------------------------------------------------------------- // Sets the equation. //----------------------------------------------------------------- void setEquation(Equation newEquation) { equation = newEquation; } //----------------------------------------------------------------- // Converts world X coordinate to screen X coordinate. //----------------------------------------------------------------- private int convertX(double x) { double offset = x - X_MIN; double result = offset * getSize().width / REAL_WORLD_WIDTH; return (int) Math.round(result); } //----------------------------------------------------------------- // Converts world Y coordinate to screen Y coordinate. //----------------------------------------------------------------- private int convertY(double y) { double offset = Y_MAX - y; double result = offset * getSize().height / REAL_WORLD_HEIGHT; return (int) Math.round(result); } //----------------------------------------------------------------- // Draws a line in world coordinates on the screen. //----------------------------------------------------------------- private void drawScreenLine(Graphics page, double xMin, double yMin, double xMax, double yMax) { page.drawLine(convertX(xMin), convertY(yMin), convertX(xMax), convertY(yMax)); } //----------------------------------------------------------------- // Draws a point in world coordinates on the screen. //----------------------------------------------------------------- private void drawScreenPoint(Graphics page, double x, double y) { page.drawLine(convertX(x), convertY(y), convertX(x), convertY(y)); } //----------------------------------------------------------------- // Draws the graph axes and equation. //----------------------------------------------------------------- public void paintComponent(Graphics page) { page.setColor(Color.white); page.fillRect(0,0,getSize().width, getSize().height); // draw the x and y axis page.setColor(Color.pink); drawScreenLine(page, X_MIN, 0, X_MAX, 0); drawScreenLine(page, 0, Y_MIN, 0, Y_MAX); // draw tick marks for (int x=X_MIN; x