Help with correcting errors in Java program. I am having a problem with the idenifiers. The program below keeps giving me these errors:

----jGRASP exec: javac -g IrregularPolyPanel.java

IrregularPolyPanel.java:16: error: cannot find symbol private ArbitraryPolygon shape = new ArbitraryPolygon(); ^ symbol: class ArbitraryPolygon location: class IrregularPolyPanel IrregularPolyPanel.java:28: error: cannot find symbol private BoxesPanel drawPanel; ^ symbol: class BoxesPanel location: class IrregularPolyPanel IrregularPolyPanel.java:16: error: cannot find symbol private ArbitraryPolygon shape = new ArbitraryPolygon(); ^ symbol: class ArbitraryPolygon location: class IrregularPolyPanel IrregularPolyPanel.java:160: error: cannot find symbol drawPanel = new BoxesPanel(npoints, xpoints, ypoints, 100); ^ symbol: class BoxesPanel location: class IrregularPolyPanel.ButtonListener 4 errors

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import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.TitledBorder; import java.text.DecimalFormat; import java.awt.Polygon; import java.awt.Graphics;

public class IrregularPolyPanel extends JPanel { private JLabel Intro, numPointsLabel, area, perimeter; private ArbitraryPolygon shape = new ArbitraryPolygon(); private int npoints; private int[] xpoints; private int[] ypoints; private String[] numbers; private JLabel Xpoints; private JTextField[] XPoints; private JLabel Ypoints; private JTextField[] YPoints; private JTextField numPoints; private JButton enter; private JPanel pane; private BoxesPanel drawPanel; private double thetaInc; private double theta; public IrregularPolyPanel() { setLayout(new BorderLayout()); numPointsLabel = new JLabel ("Number of Points:"); area = new JLabel("Area:"); perimeter = new JLabel ("Perimeter:"); enter = new JButton("Enter All Parameters"); enter.addActionListener(new ButtonListener()); numPoints = new JTextField(5); numPoints.addActionListener(new ButtonListener()); pane = new JPanel (new GridLayout(0,1,1,1)); pane.setBorder(new TitledBorder("Arbitrary Polygon Parameters")); pane.add(numPointsLabel); pane.add(numPoints); pane.add(area); pane.add(perimeter); pane.add(enter); add(pane, BorderLayout.WEST); }

private class ButtonListener implements ActionListener { public void actionPerformed (ActionEvent event) { String NUM_POINTS; int result; if(event.getSource() == enter) { NUM_POINTS = numPoints.getText(); if(NUM_POINTS.equals("")) npoints = 0; else npoints = Integer.parseInt(NUM_POINTS); if(npoints < 3) JOptionPane.showMessageDialog(null, "Invalid entry: Number of points must be more than 2.", "Error", JOptionPane.ERROR_MESSAGE); else { xpoints = new int[npoints]; ypoints = new int[npoints]; numbers = new String[npoints]; XPoints = new JTextField[npoints]; YPoints = new JTextField[npoints]; JPanel numPanel = new JPanel(new GridLayout((npoints+1), 2)); Xpoints = new JLabel(" Xpoints"); Ypoints = new JLabel(" Ypoints"); numPanel.add(Xpoints); numPanel.add(Ypoints); for(int i = 0; i < npoints; i++) { XPoints[i] = new JTextField(5); YPoints[i] = new JTextField(5); numPanel.add(XPoints[i]); numPanel.add(YPoints[i]); } result = JOptionPane.showConfirmDialog(null, numPanel, "Enter Points", JOptionPane.YES_NO_OPTION); boolean check = false; int counter = 0; while((result != JOptionPane.NO_OPTION) && (counter < npoints)) { System.out.println(counter); if(((XPoints[counter].getText()).equals("")) || ((YPoints[counter].getText()).equals(""))) xpoints[counter] = ypoints[counter] = 0; else { xpoints[counter] = Integer.parseInt(XPoints[counter].getText()); ypoints[counter] = Integer.parseInt(YPoints[counter].getText()); } if((xpoints[counter] < 1) || (ypoints[counter] < 1)) { check = false; JOptionPane.showMessageDialog(null, "Invalid entry", "Error", JOptionPane.ERROR_MESSAGE); result = JOptionPane.showConfirmDialog(null, numPanel, "Enter Points", JOptionPane.YES_NO_OPTION); } else { xpoints[counter] = Integer.parseInt(XPoints[counter].getText()); ypoints[counter] = Integer.parseInt(YPoints[counter].getText()); counter++; check = true; } } if(check == true) { shape.setNumPoints(npoints); shape.addPoints(xpoints, ypoints, npoints); thetaInc = 2 * Math.PI / npoints; theta = (npoints % 2 == 0) ? thetaInc : -Math.PI/2; for(int i = 0; i < npoints; i++) { int x1 = xpoints[i] - 100; int y1 = ypoints[i] - 100; xpoints[i] = 100+ (int) ((x1 * Math.cos(theta)) - (y1 * Math.sin(theta))) + 200; ypoints[i] = 100+ (int) ((x1 * Math.sin(theta)) + (y1 * Math.cos(theta))) + 300; theta += thetaInc; } double Perimeter = shape.getPerimeterLength(); double Area = shape.getArea(); DecimalFormat df = new DecimalFormat("#.##"); area.setText("Area: " + df.format(Area)); perimeter.setText("Perimeter: " + df.format(Perimeter)); //----------------------------------------------------------------- // Draw the Arbitrary Polygon //----------------------------------------------------------------- drawPanel = new BoxesPanel(npoints, xpoints, ypoints, 100); add(drawPanel, BorderLayout.CENTER); } } } } } }