Java tutorial
/* Java Swing, 2nd Edition By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole ISBN: 0-596-00408-7 Publisher: O'Reilly */ // PagingTester.java //A quick application that demonstrates the PagingModel. // import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Graphics; import java.awt.Polygon; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Icon; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.ScrollPaneConstants; import javax.swing.table.AbstractTableModel; import javax.swing.table.TableModel; public class PagingTester extends JFrame { public PagingTester() { super("Paged JTable Test"); setSize(300, 200); setDefaultCloseOperation(EXIT_ON_CLOSE); PagingModel pm = new PagingModel(); JTable jt = new JTable(pm); // Use our own custom scrollpane. JScrollPane jsp = PagingModel.createPagingScrollPaneForTable(jt); getContentPane().add(jsp, BorderLayout.CENTER); } public static void main(String args[]) { PagingTester pt = new PagingTester(); pt.setVisible(true); } } //PagingModel.java //A larger table model that performs "paging" of its data. This model //reports a small number of rows (like 100 or so) as a "page" of data. You //can switch pages to view all of the rows as needed using the pageDown() //and pageUp() methods. Presumably, access to the other pages of data is //dictated by other GUI elements such as up/down buttons, or maybe a text //field that allows you to enter the page number you want to display. // class PagingModel extends AbstractTableModel { protected int pageSize; protected int pageOffset; protected Record[] data; public PagingModel() { this(10000, 100); } public PagingModel(int numRows, int size) { data = new Record[numRows]; pageSize = size; // Fill our table with random data (from the Record() constructor). for (int i = 0; i < data.length; i++) { data[i] = new Record(); } } // Return values appropriate for the visible table part. public int getRowCount() { return Math.min(pageSize, data.length); } public int getColumnCount() { return Record.getColumnCount(); } // Work only on the visible part of the table. public Object getValueAt(int row, int col) { int realRow = row + (pageOffset * pageSize); return data[realRow].getValueAt(col); } public String getColumnName(int col) { return Record.getColumnName(col); } // Use this method to figure out which page you are on. public int getPageOffset() { return pageOffset; } public int getPageCount() { return (int) Math.ceil((double) data.length / pageSize); } // Use this method if you want to know how big the real table is . . . we // could also write "getRealValueAt()" if needed. public int getRealRowCount() { return data.length; } public int getPageSize() { return pageSize; } public void setPageSize(int s) { if (s == pageSize) { return; } int oldPageSize = pageSize; pageSize = s; pageOffset = (oldPageSize * pageOffset) / pageSize; fireTableDataChanged(); /* * if (pageSize < oldPageSize) { fireTableRowsDeleted(pageSize, * oldPageSize - 1); } else { fireTableRowsInserted(oldPageSize, * pageSize - 1); } */ } // Update the page offset and fire a data changed (all rows). public void pageDown() { if (pageOffset < getPageCount() - 1) { pageOffset++; fireTableDataChanged(); } } // Update the page offset and fire a data changed (all rows). public void pageUp() { if (pageOffset > 0) { pageOffset--; fireTableDataChanged(); } } // We provide our own version of a scrollpane that includes // the page up and page down buttons by default. public static JScrollPane createPagingScrollPaneForTable(JTable jt) { JScrollPane jsp = new JScrollPane(jt); TableModel tmodel = jt.getModel(); // Don't choke if this is called on a regular table . . . if (!(tmodel instanceof PagingModel)) { return jsp; } // Okay, go ahead and build the real scrollpane final PagingModel model = (PagingModel) tmodel; final JButton upButton = new JButton(new ArrowIcon(ArrowIcon.UP)); upButton.setEnabled(false); // starts off at 0, so can't go up final JButton downButton = new JButton(new ArrowIcon(ArrowIcon.DOWN)); if (model.getPageCount() <= 1) { downButton.setEnabled(false); // One page...can't scroll down } upButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ae) { model.pageUp(); // If we hit the top of the data, disable the up button. if (model.getPageOffset() == 0) { upButton.setEnabled(false); } downButton.setEnabled(true); } }); downButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ae) { model.pageDown(); // If we hit the bottom of the data, disable the down button. if (model.getPageOffset() == (model.getPageCount() - 1)) { downButton.setEnabled(false); } upButton.setEnabled(true); } }); // Turn on the scrollbars; otherwise we won't get our corners. jsp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); jsp.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS); // Add in the corners (page up/down). jsp.setCorner(ScrollPaneConstants.UPPER_RIGHT_CORNER, upButton); jsp.setCorner(ScrollPaneConstants.LOWER_RIGHT_CORNER, downButton); return jsp; } } //Record.java //A simple data structure for use with the PagingModel demo. // class Record { static String[] headers = { "Record Number", "Batch Number", "Reserved" }; static int counter; String[] data; public Record() { data = new String[] { "" + (counter++), "" + System.currentTimeMillis(), "Reserved" }; } public String getValueAt(int i) { return data[i]; } public static String getColumnName(int i) { return headers[i]; } public static int getColumnCount() { return headers.length; } } //ArrowIcon.java //A simple implementation of the Icon interface that can make //Up and Down arrows. // class ArrowIcon implements Icon { public static final int UP = 0; public static final int DOWN = 1; private int direction; private Polygon pagePolygon = new Polygon(new int[] { 2, 4, 4, 10, 10, 2 }, new int[] { 4, 4, 2, 2, 12, 12 }, 6); private int[] arrowX = { 4, 9, 6 }; private Polygon arrowUpPolygon = new Polygon(arrowX, new int[] { 10, 10, 4 }, 3); private Polygon arrowDownPolygon = new Polygon(arrowX, new int[] { 6, 6, 11 }, 3); public ArrowIcon(int which) { direction = which; } public int getIconWidth() { return 14; } public int getIconHeight() { return 14; } public void paintIcon(Component c, Graphics g, int x, int y) { g.setColor(Color.black); pagePolygon.translate(x, y); g.drawPolygon(pagePolygon); pagePolygon.translate(-x, -y); if (direction == UP) { arrowUpPolygon.translate(x, y); g.fillPolygon(arrowUpPolygon); arrowUpPolygon.translate(-x, -y); } else { arrowDownPolygon.translate(x, y); g.fillPolygon(arrowDownPolygon); arrowDownPolygon.translate(-x, -y); } } }