Help with JTextArea

Question

Hi,
I am working on a GUI Application and need some hlep.
1] When I click on Next Item button, it should clear the previously entered values of TextFields. How do I do this?
2] How do I display text in a JTextArea which appears in a Pop-up window?
I will appreciate your help and time.
Here is what I have done so far:
// FILE Name: ProductOrder.java
// Purpose: This class contains the GUI part
import javax.swing.*;
import java.awt.*; //FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class ProductOrder extends JFrame //implements ActionListener
   private Product productArray[];  //array of Product objects
   private final int NUM_OF_PROD_ELEMENTS = 6;
   private JLabel label1;
   private JLabel label2;
   private JLabel label3;
   private JTextField textField1;
   private JTextField textField2;
   private JButton button1; // Next Item button
   private JButton button2; // Receipt button
   private JButton button3; // Summary button
   // Class constructor
   public ProductOrder()
      super( "Welcome!!!" );
      productArray = new Product[NUM_OF_PROD_ELEMENTS];
      productArray[0] = new Product(100, "White Bandana", 4.98F, 0F);
      productArray[1] = new Product(200, "Green License Plate", 5.99F, 3.5F);
      productArray[2] = new Product(300, "Green Sweat Shirt", 24.99F, 7.2F);
      productArray[3] = new Product(400, "Low Profile hat", 17.98F, 4F);
      productArray[4] = new Product(500, "Gym Short", 16.98F, 4.2F);
      productArray[5] = new Product(600, "Printed Golf Balls", 8.99F, 0F);
      //float i = productArray[0].Calculate(5);
      setLayout( new FlowLayout() );
      label1 = new JLabel( "USF Campus Store" );
      add(label1);
      label2 = new JLabel( "Product Code:                                " );
      label2.setToolTipText( "Enter Product Code");
      add(label2);
      textField1 = new JTextField(2);
      add( textField1 );
      label3 = new JLabel( "Quantity:                                          " );
      label3.setToolTipText( "Enter Quantity Number");
      add(label3);
      textField2 = new JTextField(2);
      add( textField2 );
      button1 = new JButton( "Next Item");
      add( button1 );  //add button1 to JFrame
      button2 = new JButton( "Receipt");
      add( button2 );  //add button1 to JFrame
      button3 = new JButton( "Summary");
      add( button3 );  //add button1 to JFrame
      // Register event handlers
      ProductHandler handler = new ProductHandler();
      textField1.addActionListener( handler ); // Product Code
      textField2.addActionListener( handler ); // Quantity
      button1.addActionListener( handler );    // Next Item
      button2.addActionListener( handler );    // Receipt
      button3.addActionListener( handler );    // Summary
   }//end of constrct
   // Private inner class for event handling
   private class ProductHandler implements ActionListener
      public void actionPerformed( ActionEvent event )
         String string , string1;
      int pCode = 000, quant = 000;
      if (event.getSource() == textField1 )
         string = event.getActionCommand();
         //pCode = Integer.parseInt( string );
         }//end of if1
         else if (event.getSource() == textField2 )
         string1 = event.getActionCommand();
         //quant = Integer.parseInt( string1 );
         else if ( event.getSource() == button1 )  // Next Item button
            JOptionPane.showMessageDialog(null, "product code: " + textField1.getText() + " " + "Quantity: " + textField2.getText() );
         else if ( event.getSource() == button2 )  // Receipt button
      //JOptionPane.showMessageDialog(null, "product code: " + pCode );
         //JOptionPane.showMessageDialog(null, "Quantity: " + quant );
      }//end of actionPerformed( ) method
   }//end of class ProductHandler
   /*public void showOrder()
     System.out.println("\nSuccess: this is ProductOrder class. ");
} //end ProductOrder

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableCellRenderer;
import java.lang.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.FileDialog;
import java.io.*;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
public class Geometry {
CardLayout cards;
JPanel panel;
public Geometry() {
cards = new CardLayout();
panel = new JPanel(cards);
addCards();
JFrame f = new JFrame("Geometry");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setJMenuBar(getMenuBar());
f.getContentPane().add(panel);
f.setSize(500,500);
f.setLocation(0,0);
f.setVisible(true);
f.addMouseMotionListener(
new MouseMotionListener() { //anonymous inner class
//handle mouse drag event
public void mouseMoved(MouseEvent e) {
System.out.println("Mouse " + e.getX() +"," + e.getY());
public void mouseDragged(MouseEvent e) {
System.out.println("Draggg: x=" + e.getX() + "; y=" + e.getY());
// public void mouseMoved(MouseEvent me) {
// System.out.println("Moving: x=" + me.getX() + "; y=" + me.getY());
// panel.addMouseMotionListener(
// new MouseMotionListener() { //anonymous inner class
// //handle mouse drag event
// public void mouseDragged(MouseEvent me) {
// setTitle("Dragging: x=" + me.getX() + "; y=" + me.getY());
// public void mouseMoved(MouseEvent me) {
// setTitle("Moving: x=" + me.getX() + "; y=" + me.getY());
private void addCards() {
// card one
TriangleModel tri = new TriangleModel(175,100,175,250,325,250);
TriangleView view = new TriangleView(tri);
JPanel panelOne = new JPanel(new BorderLayout());
panelOne.add(view.getUIPanel(), "North");
panelOne.add(view);
panelOne.add(view.getTablePanel(), "South");
panelOne.setName("Pythagoras's Theorem");
panel.add("Pythagoras's Theorem", panelOne);
view.addMouseMotionListener(
new MouseMotionListener() { //anonymous inner class
//handle mouse drag event
public void mouseMoved(MouseEvent e) {
System.out.println("Mouse at " + e.getX() +"," + e.getY());
public void mouseDragged(MouseEvent e) {
System.out.println("Dragging: x=" + e.getX() + "; y=" + e.getY());
// card two
TestModel trin = new TestModel(175,100,175,250,325,250);
TestView viewn = new TestView(trin);
JPanel panelTwo = new JPanel(new BorderLayout());
panelTwo.add(viewn.getUIPanel(), "North");
// panelTwo.setBackground(Color.blue);
panelTwo.setName("Similar Triangles");
panelTwo.add(viewn);
panelTwo.add(viewn.getTablePanel(), "South");
viewn.addMouseMotionListener(
new MouseMotionListener() { //anonymous inner class
//handle mouse drag event
public void mouseMoved(MouseEvent e) {
System.out.println("Mouse at " + e.getX() +"," + e.getY());
public void mouseDragged(MouseEvent e) {
System.out.println("Dragging: x=" + e.getX() + "; y=" + e.getY());
panel.add("Similar Triangles", panelTwo);
JPanel panelThree = new JPanel();
panelThree.setBackground(Color.white);
panelThree.setName("Circle Theorem1");
panel.add("Circle Theorem1", panelThree);
private JMenuBar getMenuBar() {
JMenu File = new JMenu("File");
JSeparator separator1 = new JSeparator();
JMenuItem Open = new JMenuItem("Open");
// Open.addActionListener(new java.awt.event.ActionListener() {
// public void actionPerformed(java.awt.event.ActionEvent evt) {
// openActionPerformed(evt);
JMenuItem Save = new JMenuItem("Save");
JMenuItem Print = new JMenuItem("Print");
JMenuItem Exit = new JMenuItem("Exit");
Exit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
ExitActionPerformed(evt);
JMenu theorem = new JMenu("Theorem");
ActionListener l = new ActionListener() {
public void actionPerformed(ActionEvent e) {
JMenuItem item = (JMenuItem)e.getSource();
String name = item.getActionCommand();
cards.show(panel, name);
Component[] c = panel.getComponents();
for(int j = 0; j < panel.getComponentCount(); j++) {
String name = c[j].getName();
JMenuItem item = new JMenuItem(name);
item.setActionCommand(name);
item.addActionListener(l);
theorem.add(item);
JMenuBar menuBar = new JMenuBar();
JMenuBar menuBar1 = new JMenuBar();
menuBar.add(File);
File.add(Open);
File.add(separator1);
File.add(Save);
File.add(Print);
File.add(Exit);
menuBar.add(theorem);
return menuBar;
// private void openActionPerformed(java.awt.event.ActionEvent evt) {
// FileDialog fileDialog = new FileDialog(this, "Open...", FileDialog.LOAD);
// fileDialog.show();
// if (fileDialog.getFile() == null)
// return;
// fileName = fileDialog.getDirectory() + File.separator + fileDialog.getFile();
// FileInputStream fis = null;
// String str = null;
// try {
// fis = new FileInputStream(fileName);
// int size = fis.available();
// byte[] bytes = new byte [size];
// fis.read(bytes);
// str = new String(bytes);
// } catch (IOException e) {
// } finally {
// try {
// fis.close();
// } catch (IOException e2) {
// if (str != null)
// textBox.setText(str);
private void ExitActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
System.exit(0);
public static void main(String[] args) {
new Geometry();
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableCellRenderer;
public class Triangle
public Triangle()
TriangleModel tri = new TriangleModel(175,100,175,250,325,250);
TriangleView view = new TriangleView(tri);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(view.getUIPanel(), "North");
f.getContentPane().add(view);
f.getContentPane().add(view.getTablePanel(), "South");
f.setSize(500,500);
f.setLocation(200,200);
f.setVisible(true);
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import javax.swing.JTable;
import javax.swing.event.MouseInputAdapter;
* TriangleControl.java
* Created on 06 February 2005, 01:19
* @author Rahindra Naidoo
public class TriangleControl extends MouseInputAdapter
TriangleView view;
TriangleModel model;
Point start;
boolean dragging, altering;
Rectangle lineLens; // used for line selection
public TriangleControl(TriangleView tv)
view = tv;
model = view.getModel();
dragging = altering = false;
lineLens = new Rectangle(0, 0, 6, 6);
public void mousePressed(MouseEvent e)
Point p = e.getPoint();
lineLens.setLocation(p.x - 3, p.y - 3);
// are we over a line
if(model.isLineSelected(lineLens))
start = p;
altering = true;
// or are we within the triangle
else if(model.contains(p))
start = p;
dragging = true;
public void mouseReleased(MouseEvent e)
altering = false;
dragging = false;
view.getCentroidLabel().setText("centroid location: " +
model.findCentroid());
view.repaint(); // for the construction lines
public void mouseDragged(MouseEvent e)
Point p = e.getPoint();
if(altering)
int x = p.x - start.x;
int y = p.y - start.y;
model.moveSide(x, y, p);
updateTable();
view.repaint();
start = p;
else if(dragging)
int x = p.x - start.x;
int y = p.y - start.y;
model.translate(x, y);
view.repaint();
start = p;
private void updateTable()
String[] lengths = model.getLengths();
String[] squares = model.getSquares();
String[] angles = model.getAngles();
JTable table = view.getTable();
for(int j = 0; j < angles.length; j++)
table.setValueAt(lengths[j], 1, j + 1);
table.setValueAt(squares[j], 2, j + 1);
table.setValueAt(angles[j], 3, j + 1);
view.getCentroidLabel().setText("centroid location: " +
model.findCentroid());
* TriangleModel.java
* Created on 06 February 2005, 01:18
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableCellRenderer;
* @author Rahindra Naidoo
public class TriangleModel // (x1, y1)
{                                         //      |\
static final int SIDES = 3; // | \
private int cx, cy; // | \
Polygon triangle; // |_ _\ (x3, y3)
int selectedIndex; // (x2, y2)
NumberFormat nf;
Line2D[] medians;
Point2D centroid;
public TriangleModel(int x1, int y1, int x2, int y2, int x3, int y3)
int[] x = new int[] { x1, x2, x3 };
int[] y = new int[] { y1, y2, y3 };
triangle = new Polygon(x, y, SIDES);
nf = NumberFormat.getNumberInstance();
nf.setMaximumFractionDigits(1);
public boolean contains(Point p)
// Polygon.contains doesn't work well enough
return (new Area(triangle)).contains(p);
public boolean isLineSelected(Rectangle r)
Line2D line = new Line2D.Double();
for(int j = 0; j < SIDES; j++)
int[] x = triangle.xpoints;
int[] y = triangle.ypoints;
int x1 = x[j];
int y1 = y[j];
int x2 = x[(j + 1) % SIDES];
int y2 = y[(j + 1) % SIDES];
line.setLine(x1, y1, x2, y2);
if(line.intersects(r))
selectedIndex = j;
return true;
selectedIndex = -1;
return false;
* Only works for right triangle with right angle at (x2, y2)
public void moveSide(int dx, int dy, Point p)
int[] x = triangle.xpoints;
int[] y = triangle.ypoints;
switch(selectedIndex)
case 0:
x[0] += dx;
x[1] += dx;
break;
case 1:
y[1] += dy;
y[2] += dy;
break;
case 2:
double rise = y[2] - y[0];
double run = x[2] - x[0];
double slope = rise/run;
// rise / run == (y[2] - p.y) / (x[2] - p.x)
x[2] = p.x + (int)((y[2] - p.y) / slope);
// rise / run == (p.y - y[0]) / (p.x - x[0])
y[0] = p.y - (int)((p.x - x[0]) * slope);
public void translate(int dx, int dy)
triangle.translate(dx, dy);
public Polygon getTriangle()
return triangle;
public String findCentroid()
int[] x = triangle.xpoints;
int[] y = triangle.ypoints;
// construct the medians defined as the line from
// any vertex to the midpoint of the opposite line
medians = new Line2D[x.length];
for(int j = 0; j < x.length; j++)
int next = (j + 1) % x.length;
int last = (j + 2) % x.length;
Point2D vertex = new Point2D.Double(x[j], y[j]);
// get midpoint of line opposite vertex
double dx = ((double)x[last] - x[next])/2;
double dy = ((double)y[last] - y[next])/2;
Point2D oppLineCenter = new Point2D.Double(x[next] + dx,
y[next] + dy);
medians[j] = new Line2D.Double(vertex, oppLineCenter);
// centroid is located on any median 2/3 the way from the
// vertex (P1) to the midpoint (P2) on the opposite side
double[] lengths = getSideLengths();
double dx = (medians[0].getX2() - medians[0].getX1())*2/3;
double dy = (medians[0].getY2() - medians[0].getY1())*2/3;
double px = medians[0].getX1() + dx;
double py = medians[0].getY1() + dy;
//System.out.println("px = " + nf.format(px) +
// "\tpy = " + nf.format(py));
centroid = new Point2D.Double(px, py);
return "(" + nf.format(px) + ", " + nf.format(py) + ")";
public String[] getAngles()
double[] lengths = getSideLengths();
String[] vertices = new String[lengths.length];
for(int j = 0; j < lengths.length; j++)
int opp = (j + 1) % lengths.length;
int last = (j + 2) % lengths.length;
double top = lengths[j] * lengths[j] +
lengths[last] * lengths[last] -
lengths[opp] * lengths[opp];
double divisor = 2 * lengths[j] * lengths[last];
double vertex = Math.acos(top / divisor);
vertices[j] = nf.format(Math.toDegrees(vertex));
return vertices;
public String[] getLengths()
double[] lengths = getSideLengths();
String[] lengthStrs = new String[lengths.length];
for(int j = 0; j < lengthStrs.length; j++)
lengthStrs[j] = nf.format(lengths[j]);
return lengthStrs;
public String[] getSquares()
double[] lengths = getSideLengths();
String[] squareStrs = new String[lengths.length];
for(int j = 0; j < squareStrs.length; j++)
squareStrs[j] = nf.format(lengths[j] * lengths[j]);
return squareStrs;
private double[] getSideLengths()
int[] x = triangle.xpoints;
int[] y = triangle.ypoints;
double[] lengths = new double[SIDES];
for(int j = 0; j < SIDES; j++)
int next = (j + 1) % SIDES;
lengths[j] = Point.distance(x[j], y[j], x[next], y[next]);
return lengths;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableCellRenderer;
* TriangleView.java
* Created on 06 February 2005, 01:21
public class TriangleView extends JPanel
private TriangleModel model;
private Polygon triangle;
private JTable table;
private JLabel centroidLabel;
private boolean showConstruction;
TriangleControl control;
public TriangleView(TriangleModel model)
this.model = model;
triangle = model.getTriangle();
showConstruction = false;
control = new TriangleControl(this);
addMouseListener(control);
addMouseMotionListener(control);
public void paintComponent(Graphics g)
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.draw(triangle);
if(model.medians == null)
centroidLabel.setText("centroid location: " + model.findCentroid());
// draw medians and centroid point
if(showConstruction && !control.dragging)
g2.setPaint(Color.red);
for(int j = 0; j < 3; j++)
g2.draw(model.medians[j]);
g2.setPaint(Color.blue);
g2.fill(new Ellipse2D.Double(model.centroid.getX() - 2,
model.centroid.getY() - 2, 4, 4));
public TriangleModel getModel()
return model;
public JTable getTable()
return table;
public JLabel getCentroidLabel()
return centroidLabel;
public JPanel getUIPanel()
JCheckBox showCon = new JCheckBox("show construction");
showCon.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent e)
boolean state = ((JCheckBox)e.getSource()).isSelected();
showConstruction = state;
repaint();
JPanel panel = new JPanel();
panel.add(showCon);
return panel;
public JPanel getTablePanel()
String[] headers = new String[] { "", "", "", "" };
// row and column data labels
String[] rowHeaders = {
"sides", "lengths", "squares", "angles", "degrees"
String[] sidesRow = { "vertical", "horizontal", "hypotenuse" };
String[] anglesRow = { "hyp to ver", "ver to hor", "hor to hyp" };
// collect data from model
String[] angles = model.getAngles();
String[] lengths = model.getLengths();
String[] squares = model.getSquares();
String[][] allData = { sidesRow, lengths, squares, anglesRow, angles };
int rows = 5;
int cols = 4;
Object[][] data = new Object[rows][cols];
for(int row = 0; row < rows; row++)
data[row][0] = rowHeaders[row];
for(int col = 1; col < cols; col++)
data[row][col] = allData[row][col - 1];
table = new JTable(data, headers)
public boolean isCellEditable(int row, int col)
return false;
DefaultTableCellRenderer renderer =
(DefaultTableCellRenderer)table.getDefaultRenderer(String.class);
renderer.setHorizontalAlignment(JLabel.CENTER);
centroidLabel = new JLabel("centroid location: ", JLabel.CENTER);
Dimension d = centroidLabel.getPreferredSize();
d.height = table.getRowHeight();
centroidLabel.setPreferredSize(d);
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createTitledBorder("triangle data"));
panel.add(table);
panel.add(centroidLabel, "South");
return panel;
PLEASE HELP ME TO LABEL THE TRIANGLE AND CHANGE THE VALUES OF THE JTABLE - to SHOW ASquare b Square and C square as well as a label on the bottom of the screen to show A^2 + B^2 = C^2 ...
ThANKS