// 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.
//
import javax.swing.table.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public 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;
}
}
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