import java.awt.*; import javax.swing.*; import java.awt.geom.Line2D; import javax.swing.event.TableModelEvent; import javax.swing.event.TableModelListener; import javax.swing.table.*; /** * Demonstrates the use of a custom table model, and some other * configuration, for a JTable. The program lets the user enter * (x,y) coordinates of some points, and it draws a simple * scatter plot of all the points in the table for which * both the x and the y coordinate is defined. This class can * be run as a standalone application and has a nested class * that can be used to run the program as an applet. */ public class ScatterPlotTableDemo extends JPanel { /** * The main routine simply opens a window that shows a ScatterPlotTableDemo panel. */ public static void main(String[] args) { JFrame window = new JFrame("ScatterPlotTableDemo"); ScatterPlotTableDemo content = new ScatterPlotTableDemo(); window.setContentPane(content); window.pack(); window.setResizable(false); Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); window.setLocation( (screenSize.width - window.getWidth())/2, (screenSize.height - window.getHeight())/2 ); window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); window.setVisible(true); } /** * The public static class ScatterPlotTableDemo.Applet represents this program * as an applet. The applet's init() method simply sets the content * pane of the applet to be a ScatterPlotTableDemo. To use the applet on * a web page, use code="ScatterPlotTableDemo$Applet.class" as the name of * the class. A reasonable size for the applet is 580 by 300. */ public static class Applet extends JApplet { public void init() { ScatterPlotTableDemo content = new ScatterPlotTableDemo(); setContentPane( content ); } } /** * This class defines the TableModel that is used for the JTable in this * program. The table has three columns. Column 0 simply holds the * row number of each row. Column 1 holds the x-coordinates of the * points for the scatter plot, and Column 2 holds the y-coordinates. * The table has 25 rows. No support is provided for adding more rows. */ private class CoordInputTableModel extends AbstractTableModel { private Double[] xCoord = new Double[25]; // Data for Column 1, initially all null. private Double[] yCoord = new Double[25]; // Data for Column 2, initially all null. public int getColumnCount() { // Tells caller how many columns there are. return 3; } public int getRowCount() { // Tells caller how many rows there are. return xCoord.length; } public Object getValueAt(int row, int col) { // Get the data for one cell. if (col == 0) return (row+1); // Column 0 holds the row number. else if (col == 1) return xCoord[row]; // Column 1 holds the x-coordinates. else return yCoord[row]; // column 2 holds the y-coordinates. } public Class getColumnClass(int col) { // Get data type of column. if (col == 0) return Integer.class; else return Double.class; } public String getColumnName(int col) { // Returns a name for column header. if (col == 0) return "Num"; else if (col == 1) return "X"; else return "Y"; } public boolean isCellEditable(int row, int col) { // Can user edit cell? return col > 0; } public void setValueAt(Object obj, int row, int col) { // Changes cell value. // (This method is called by the system if the value of the cell // needs to be changed because the user has edited the current value. // It can also be called to change the value programmatically. // In this case, only columns 1 and 2 can be modified, and the data // type for obj must be Double. The method fireTableCellUpdated() // has to be called to send a TableModelEvent to registered listeners.) if (col == 1) xCoord[row] = (Double)obj; else if (col == 2) yCoord[row] = (Double)obj; fireTableCellUpdated(row, col); } } // end nested class CoordInputTableModel /** * Defines the display area where a scatter plot of the points * in the table is drawn. The range of values shown in the plot * is adjusted to make sure that all the points are visible. * Note that only points for which both coordinates are * defined are drawn. */ private class Display extends JPanel { public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; double min = -0.5; // Minimum of the range of values displayed. double max = 5; // Maximum of the range of value displayed. int count = model.getRowCount(); for (int i = 0; i < count; i++) { Double x = (Double)model.getValueAt(i, 1); // (Return type of getValue() is Object.) Double y = (Double)model.getValueAt(i, 2); if (x != null && y != null) { // Adjust max and min to include x and y. if (x < min) min = x - 0.5; if (x > max) max = x + 0.5; if (y < min) min = y - 0.5; if (y > max) max = y + 0.5; } } /* Apply a translation so that the drawing coordinates on the display correspond to the range of values that I want to show. */ g2.translate(getWidth()/2,getHeight()/2); g2.scale(getWidth()/(max-min), -getHeight()/(max-min)); g2.translate(-(max+min)/2, -(max+min)/2); /* I want to be able to draw lines that are a certain number of pixels long. Unfortunately, the unit of length is no longer equal to the size of a pixel, so I have to figure out how big a pixel is in the new coordinates. Also, horizontal and vertical size can be different. */ double pixelWidth = (max-min)/getWidth(); // Horizontal size of a pixel in new coords. double pixelHeight = (max-min)/getHeight(); // Vertical size of a pixel in new coord. /* When the thickness of a BasicStroke is set to 0, the actual width of the stroke will be as small as possible, that is, one pixel wide. */ g2.setStroke(new BasicStroke(0)); /* Draw x and y axes with tick marks to mark the integers (but don't draw the tick marks if there would be more than 100 of them. */ g2.setColor(Color.BLUE); g2.draw( new Line2D.Double(min,0,max,0)); g2.draw( new Line2D.Double(0,min,0,max)); if (max - min < 100) { int tick = (int)min; while (tick <= max) { g2.draw(new Line2D.Double(tick,0,tick,3*pixelHeight)); g2.draw(new Line2D.Double(0,tick,3*pixelWidth,tick)); tick++; } } /* Draw a small crosshair at each point from the table. */ g2.setColor(Color.RED); for (int i = 0; i < count; i++) { Double x = (Double)model.getValueAt(i, 1); Double y = (Double)model.getValueAt(i, 2); if (x != null && y != null) { g2.draw(new Line2D.Double(x-3*pixelWidth,y,x+3*pixelWidth,y)); g2.draw(new Line2D.Double(x,y-3*pixelHeight,x,y+3*pixelHeight)); } } } } // end nested class Display private JTable table; // The JTable where the points are input. private CoordInputTableModel model; // The TableModel for the table. private Display display; // The panel where the scatter plot is drawn. /** * The constructor creates the model, table, and display. The table and display * are added to this panel. The table is configured to show grid lines between * cells, to disallow dragging of a column to a new position, to increase the * height of the cells, to set different preferred sizes for the columns, and * to set a preferred size for the viewport of the scrollpane that will display * the table. A listener is set up on the model so that the display can be * changed whenever the data in the model changes. (Also, some random data is * put in the table, as an example to help the user see what is going on -- this * is just done for demonstration purposes.) */ public ScatterPlotTableDemo() { setLayout(new BorderLayout()); setBorder(BorderFactory.createLineBorder(Color.BLACK,1)); model = new CoordInputTableModel(); table = new JTable(model); table.setRowHeight(25); table.setShowGrid(true); table.setGridColor(Color.BLACK); table.setPreferredScrollableViewportSize(new Dimension(250, 300)); table.getColumnModel().getColumn(0).setPreferredWidth(50); table.getColumnModel().getColumn(1).setPreferredWidth(100); table.getColumnModel().getColumn(2).setPreferredWidth(100); table.getTableHeader().setReorderingAllowed(false); add(new JScrollPane(table), BorderLayout.WEST); for (int i = 0; i < 6; i++) { // Fill first 6 rows with random values. model.setValueAt( (int)(450*Math.random())/100.0, i, 1 ); model.setValueAt( (int)(450*Math.random())/100.0, i, 2 ); } display = new Display(); display.setPreferredSize(new Dimension(300,300)); display.setBackground(Color.WHITE); add(display, BorderLayout.CENTER); model.addTableModelListener(new TableModelListener() { // Install a TableModelListener that will respond to any // changes in the model's data by redrawing the display that // shows the scatter plot. public void tableChanged(TableModelEvent e) { display.repaint(); } }); } }