问题
The code I'm referencing is proprietary and requires a multicast server, so I can't post an SSCCE snippet. I understand this may preclude any helpful insight which would elicit viable responses...
I'm compiling with Java 7 u 9.
I'm currently using a JTable in a GUI app that listens to multicast data, and displays it as it arrives. When scrolling the table or resizing columns, the app responds excruciatingly slow.
I thought I structured my code appropriately.
I used a wrapper class, and in it's main() function, it creates an instance of itself, which processes command line arguments, creates listeners, creates the JFrame and calls the class that returns a JTable. This is all done outside of the event dispatch thread.
Then, in the next line, I used the invokeLater() method to create a thread that handles all of the GUI rendering. It creates a JScrollPane, adds the JTable to the scroll pane, sets the scroll bars, sets the viewport, sets the scroll mode, and adds the JScrollPane to a JFrame . This is all handled within the event dispatch thread.
The rows typically populate fairly quick, with the occasional screen freeze (some of the rows contain 30 or more lines), but the responsiveness seems acceptable. However, when scrolling or resizing columns, the response is very slow.
All of the examples I've seen, including the SwingX SwingLabs demo all refer to an initial dataset that is loaded up front. I need an example of using a JTable with streaming data.
Can anyone point me to such an example/demo?
This is my main() snippet...
public static void main(String args[])
{
final JXTrapTableGUI ttg = new JXTrapTableGUI(args);
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
ttg.createAndShowGUI();
}
});
}
PS. I want to thank each and everyone who responded. I've been pulled off this project until March 11th, but I will review all responses on that date.
回答1:
I do not think that JTable works well with streaming data at all. All of the optimization techniques you mentioned, like keeping processing off of the Event Dispatch Thread, are irrlevant if the TableModel does not contain a real list but instead some connection to a data stream.
Without seeing how you attempted to handle this, it's hard to know exactly why it's slow. But here is how I would make it repsonsive:
Create a ListModel that stores a List - not a reference to a stream, just a plain List.
Have another Thread capture Multicast Data from the stream, lets call it DataStreamCollector.
Then launch a Thread that runs on a timer (javax.swing.Timer) that checks with the DataStreamCollector and updates the ListModel as needed.
My design here is assuming that UI responsiveness is more important than 100% synchronization with the data stream. Adjusting the timers should let you trade off having an up-to-date table with having a responsive UI.
回答2:
Somewhere lost in Oracles clean_up to the trash (old Suns tutorials),
This project was called ChristmastTree, is about JTable & Performance,
Standard Java code before crazy & messy SwingWorker invoked from black hole called Executor
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.plaf.basic.*;
import javax.swing.table.*;
/**
* CTTable extends JTable doing the following: <ul> <li>The UI is forced to be
* CTTableUI so that a customer CellRendererPane can be installed.
* <li>getCellRenderer is overriden to return the TableCellRenderer passed into
* the constructor. <li>tableChanged is overriden to pass the call to super only
* if the cell is visible. </ul>
*/
public class CTTable extends JTable {
private static final long serialVersionUID = 1L;
private CTTableCellRenderer renderer;
public CTTable(CTTableCellRenderer renderer) {
super();
this.renderer = renderer;
renderer.setFont(getFont());
}
@Override
public void updateUI() {
super.updateUI();
//Force the UI to be an instanceof CTTableUI. This approach will not work
//if you need to support more than one look and feel in your application.
setUI(new CTTableUI());
}
@Override
public void setFont(Font font) {
super.setFont(font);
if (renderer != null) {
renderer.setFont(font);
}
}
@Override
public TableCellRenderer getCellRenderer(int row, int column) {
return renderer;
}
@Override
public void tableChanged(TableModelEvent e) {
if (e instanceof VisibleTableModelEvent && !((VisibleTableModelEvent) e).isVisible(this)) {
return;// Do nothing if this cell isn't visible.
}
super.tableChanged(e);
}
private static class CTTableUI extends BasicTableUI {
@Override
public void installUI(JComponent c) {
super.installUI(c);// Overriden to install our own CellRendererPane
c.remove(rendererPane);
rendererPane = new CTCellRendererPane();
c.add(rendererPane);
}
}
/**
* CTCellRendererPane overrides paintComponent to NOT clone the Graphics
* passed in and NOT validate the Component passed in. This will NOT work if
* the painting code of the Component clobbers the graphics (scales it,
* installs a Paint on it...) and will NOT work if the Component needs to be
* validated before being painted.
*/
private static class CTCellRendererPane extends CellRendererPane {
private static final long serialVersionUID = 1L;
private Rectangle tmpRect = new Rectangle();
@Override
public void repaint() {
// We can safely ignore this because we shouldn't be visible
}
@Override
public void repaint(int x, int y, int width, int height) {
}
@Override
public void paintComponent(Graphics g, Component c, Container p, int x,
int y, int w, int h, boolean shouldValidate) {
if (c == null) {
if (p != null) {
Color oldColor = g.getColor();
g.setColor(p.getBackground());
g.fillRect(x, y, w, h);
g.setColor(oldColor);
}
return;
}
if (c.getParent() != this) {
this.add(c);
}
c.setBounds(x, y, w, h);
// As we are only interested in using a JLabel as the renderer,
//which does nothing in validate we can override this to do nothing,
//if you need to support components that can do layout, this will
//need to be commented out, or conditionally validate.
shouldValidate = false;
if (shouldValidate) {
c.validate();
}
boolean wasDoubleBuffered = false;
JComponent jc = (c instanceof JComponent) ? (JComponent) c : null;
if (jc != null && jc.isDoubleBuffered()) {
wasDoubleBuffered = true;
jc.setDoubleBuffered(false);
}//Don't create a new Graphics, reset the clip and translate the origin.
Rectangle clip = g.getClipBounds(tmpRect);
g.clipRect(x, y, w, h);
g.translate(x, y);
c.paint(g);
g.translate(-x, -y);
g.setClip(clip.x, clip.y, clip.width, clip.height);
if (wasDoubleBuffered) {
jc.setDoubleBuffered(true);
}
c.setBounds(-w, -h, 0, 0);
}
}
}
.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;
/**
* A custom TableCellRenderer that overrides a handful of methods: <ul>
* <li>isOpaque and setBackground are overridden to avoid filling the
* background, if possible. <li>firePropertyChange is overridden to do nothing.
* If you need to support HTML text in the renderer than this should NOT be
* overridden. <li>paint is overridden to forward the call directly to the UI,
* avoiding the creation of a Graphics. This will NOT work if you need the
* renderer to contain other childre or the Graphics is clobbered as part of
* painting the UI. </ul>
*/
public class CTTableCellRenderer extends DefaultTableCellRenderer {
private static final long serialVersionUID = 1L;
private Color background;
private Color foreground;
private Color editableForeground;
private Color editableBackground;
private Border focusBorder;
public CTTableCellRenderer() {
focusBorder = UIManager.getBorder("Table.focusCellHighlightBorder");
editableForeground = UIManager.getColor("Table.focusCellForeground");
editableBackground = UIManager.getColor("Table.focusCellBackground");
}
@Override
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
boolean negative = (value != null && ((Integer) value).intValue() < 0);
// Reset the background based on the sign of the value.
if (isSelected) {
setForeground(table.getSelectionForeground());
setBackground(table.getSelectionBackground());
} else {
setForeground(table.getForeground());
if (!negative) {
setBackground(null);
} else {
setBackground(Color.red);
}
}//NOTICE that we do NOT set the font here, because CTTable knows about
//us, it will set the font as appropriate.
if (hasFocus) {
setBorder(focusBorder);
if (table.isCellEditable(row, column)) {
setForeground(editableForeground);
setBackground(editableBackground);
}
} else {
setBorder(noFocusBorder);
}
setValue(value);
return this;
}
@Override
protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
// As long as you don't have any HTML text, this override is ok.
}
@Override// This override is only appropriate if this will never contain
// any children AND the Graphics is not clobbered during painting.
public void paint(Graphics g) {
ui.update(g, this);
}
@Override
public void setBackground(Color c) {
this.background = c;
}
@Override
public Color getBackground() {
return background;
}
@Override
public void setForeground(Color c) {
this.foreground = c;
}
@Override
public Color getForeground() {
return foreground;
}
@Override
public boolean isOpaque() {
return (background != null);
}
@Override // This is generally ok for non-Composite components (like Labels)
public void invalidate() {
}
@Override // Can be ignored, we don't exist in the containment hierarchy.
public void repaint() {
}
}
.
import javax.swing.table.*;
import java.util.*;
/**
* CTTableModel, a TableModel, models a set of Datas as the rows. The data is
* stored in a List of Lists. As the changes come in against a particular Data
* object we also contain a map from Data to row. This can obviously be made
* faster by pushing the row to the Data, but this may not be feasable in
* applications of this sort.
*/
public class CTTableModel extends AbstractTableModel {
private static final long serialVersionUID = 1L;
/**
* Maps from Data to an integer id giving the row of the data.
*/
private Map rowMap;
/**
* Number of columns to display.
*/
private int columns;
/**
* A List of Lists.
*/
private java.util.List rowData;
/**
* If true, batch cell updates using sharedModelEvent.
*/
private boolean batchChange;
/**
* Shared model event.
*/
private VisibleTableModelEvent sharedModelEvent;
public CTTableModel(int columns) {
this.columns = columns;
// Notice how they are not synchronized, we do NOT access this class
// from another thread, and therefore do not have to worry about
// synchronization.
rowData = new ArrayList();
rowMap = new HashMap();
}
public void addRow(Data rowID) {
int row = rowData.size();
rowMap.put(rowID, new Integer(row));
ArrayList colData = new ArrayList();
for (int counter = 0; counter < columns; counter++) {
colData.add(null);
}
rowData.add(colData);
fireTableRowsInserted(row, row);
}
/**
* Toggles batch updates. When true and model changes are notified using a
* VisibleTableModelEvent.
*
* @param batch
*/
public void setBatchUpdates(boolean batch) {
this.batchChange = batch;
if (sharedModelEvent == null) {
sharedModelEvent = new VisibleTableModelEvent(this);
}
sharedModelEvent.reset();
}
public boolean getBatchUpdates() {
return batchChange;
}
/**
* Sets the display value for a particular Data item at a particular cell.
* If notify is true listeners are notified, otherwise no listeners are
* notified.
*
* @param rowID
* @param col
* @param data
* @param notify
*/
public void set(Data rowID, int col, Object data, boolean notify) {
int row = ((Integer) rowMap.get(rowID)).intValue();
((java.util.List) rowData.get(row)).set(col, data);
if (notify) {
if (batchChange) {
sharedModelEvent.set(row, col);
fireTableChanged(sharedModelEvent);
} else {
fireTableCellUpdated(row, col);
}
}
}
@Override
public int getRowCount() {
return rowData.size();
}
@Override
public int getColumnCount() {
return columns;
}
@Override
public Object getValueAt(int rowIndex, int columnIndex) {
return ((java.util.List) rowData.get(rowIndex)).get(columnIndex);
}
}
.
/**
* Unique ID for the data.
*/
public class Data {
/**
* This is overriden to remind developers they should have an intelligent
* equals and hashCode. You do not need to override either of them, but if
* you override one you need to override the other. Additionaly, because
* they are used extensively to map the data that has changed to the table,
* equals and hashCode MUST be fast, cache data if you need to!
*
* @param x
*/
@Override
public boolean equals(Object x) {
return (this == x);
}
/**
* This is overriden to remind developers they should have an intelligent
* equals and hashCode. You do not need to override either of them, but if
* you override one you need to override the other. Additionaly, because
* they are used extensively to map the data that has changed to the table,
* equals and hashCode MUST be fast, cache data if you need to!
*/
@Override
public int hashCode() {
return super.hashCode();
}
}
.
import java.util.ArrayList;
/**
* DataChange is used to associate a Data Object with a column identifier that
* has changed. To avoid loads of garbage per update DataChanges are cached and
* reused.
*/
public class DataChange {
private static ArrayList sharedDataChanges = new ArrayList();
private Data data;
private int col;
private int hashCode;
/**
* Obtains a DataChange for the specified Data and column.
*
* @param data
* @param col
* @return
*/
public static DataChange getDataChange(Data data, int col) {
synchronized (sharedDataChanges) {
int size = sharedDataChanges.size();
if (size > 0) {
DataChange change = (DataChange) sharedDataChanges.remove(size - 1);
change.data = data;
change.col = col;
return change;
}
}
return new DataChange(data, col);
}
/**
* Indicates the DataChange is no longer needed and can be reused.
*
* @param change
*/
public static void releaseDataChange(DataChange change) {
synchronized (sharedDataChanges) {
sharedDataChanges.add(change);
}
}
DataChange(Data data, int col) {
this.data = data;
this.col = col;
hashCode = (data.hashCode() | col);
}
public Data getData() {
return data;
}
public int getColumn() {
return col;
}
@Override
public int hashCode() {
return hashCode;
}
public boolean equals(DataChange dc) {
if (dc == this) {
return true;
}
DataChange o = (DataChange) dc;
return (o.data == data && o.col == col);
}
}
.
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
/**
* The Main controller, responsible for wiring everything together. Pressing
* return in any of the fields will trigger recreation of everything.
*/
public class Main implements ActionListener {
// properties: columnCount, rowCount, updateSleepTime, eqSleepTime,
// threshold, generateSleep, generatorBatchCount
private static final Insets EMPTY_INSETS = new Insets(0, 0, 0, 0);
private JTextField columnCount;
private JTextField rowCount;
private JTextField updateSleepTime;
private JTextField eqSleepTime;
private JTextField threshold;
private JTextField generateSleep;
private JTextField generatorBatchCount;
private JFrame frame;
static JLabel totalUpdateTime;
static JLabel notifyTime;
static JLabel paintTime;
static JLabel updateCount;
private JTable table;
private UpdateThread updateThread;
private GeneratorThread generatorThread;
private CTTableModel tableModel;
private static int NUM_COLUMNS = 40;// Initial values for the 7 properties.
private static int NUM_ROWS = 3000;
private static int UPDATE_SLEEP_TIME = 500;
private static int EQ_SLEEP_TIME = 10;
private static int UPDATE_ALL_THRESHOLD = 400000;
private static int GENERATOR_SLEEP_TIME = 40;
private static int BATCH_SIZE = 1000;
Main() {
frame = new JFrame();
frame.getContentPane().setLayout(new GridBagLayout());
columnCount = add("Columns: ", NUM_COLUMNS);
rowCount = add("Rows: ", NUM_ROWS);
updateSleepTime = add("Update Sleep: ", UPDATE_SLEEP_TIME);
eqSleepTime = add("EQ Sleep: ", EQ_SLEEP_TIME);
threshold = add("Update All Threshold: ", UPDATE_ALL_THRESHOLD);
generateSleep = add("Generator Sleep: ", GENERATOR_SLEEP_TIME);
generatorBatchCount = add("Batch Size: ", BATCH_SIZE);
table = new CTTable(new CTTableCellRenderer());
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
JScrollPane sp = new JScrollPane(table);
frame.getContentPane().add(sp, new GridBagConstraints(0, 3, 6, 1, 1, 1,
GridBagConstraints.WEST, GridBagConstraints.BOTH, EMPTY_INSETS, 0, 0));
ChangeListener changeListener = new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
BoundedRangeModel m = (BoundedRangeModel) (e.getSource());
if (updateThread != null) {
updateThread.setUpdatesEnabled(!(m.getValueIsAdjusting()));
}
}
};
sp.getVerticalScrollBar().getModel().addChangeListener(changeListener);
sp.getHorizontalScrollBar().getModel().addChangeListener(changeListener);
totalUpdateTime = new JLabel(" ");
notifyTime = new JLabel(" ");
paintTime = new JLabel(" ");
updateCount = new JLabel(" ");
JPanel statusPanel = new JPanel(new GridBagLayout());
frame.getContentPane().add(statusPanel, new GridBagConstraints(0, 4, 6, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
statusPanel.add(totalUpdateTime, new GridBagConstraints(0, 0, 1, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
statusPanel.add(notifyTime, new GridBagConstraints(1, 0, 1, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
statusPanel.add(paintTime, new GridBagConstraints(2, 0, 1, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
statusPanel.add(updateCount, new GridBagConstraints(3, 0, 1, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
frame.setTitle("Christmas Tree Demo Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(0, 0, 1000, 800);
frame.setVisible(true);
try {
Thread.sleep(5000);
} catch (InterruptedException ie) {
}
reset();
}
@Override
public void actionPerformed(ActionEvent ae) {
reset();
}
private JTextField add(String name, int defaultValue) {
Container parent = frame.getContentPane();
int row = parent.getComponentCount() / 6;
int col = parent.getComponentCount() % 6;
parent.add(new JLabel(name), new GridBagConstraints(col, row, 1, 1, 0, 0,
GridBagConstraints.WEST, 0, EMPTY_INSETS, 0, 0));
JTextField tf = new JTextField(Integer.toString(defaultValue));
tf.addActionListener(this);
parent.add(tf, new GridBagConstraints(col + 1, row, 1, 1, 1, 0,
GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, EMPTY_INSETS, 0, 0));
return tf;
}
private void reset() {
System.out.println("Columns: " + getInt(columnCount));
System.out.println("Rows: " + getInt(rowCount));
System.out.println("Update Sleep: " + getInt(updateSleepTime));
System.out.println("EQ Sleep: " + getInt(eqSleepTime));
System.out.println("Update All Threshold: " + getInt(threshold));
System.out.println("Generator Sleep: " + getInt(generateSleep));
System.out.println("Batch Size: " + getInt(generatorBatchCount));
if (updateThread != null) {
System.out.println("interrupting!");
updateThread.interrupt();
generatorThread.interrupt();
}
int cols = getInt(columnCount);
tableModel = new CTTableModel(cols);
ArrayList<Data> data = new ArrayList<Data>();
for (int counter = getInt(rowCount) - 1; counter >= 0; counter--) {
Data dataID = new Data();
data.add(dataID);
tableModel.addRow(dataID);
for (int colCounter = 0; colCounter < cols; colCounter++) {
if (colCounter % 2 == 0) {
tableModel.set(dataID, colCounter,
new Integer(counter * 100 + colCounter), false);
} else {
tableModel.set(dataID, colCounter,
new Integer(counter * -100 + colCounter), false);
}
}
}
table.setModel(tableModel);
generatorThread = new GeneratorThread(data, getInt(generateSleep),
getInt(generatorBatchCount), getInt(columnCount));
updateThread = new UpdateThread(generatorThread, tableModel,
getInt(updateSleepTime), getInt(eqSleepTime), getInt(threshold));
generatorThread.start();
updateThread.start();
}
private int getInt(JTextField tf) {
try {
return Integer.parseInt(tf.getText());
} catch (NumberFormatException nfe) {
System.out.println("exception getting int: " + nfe);
}
return 0;
}
public static void main(String[] args) {
Main main = new Main();
}
}
... will be continue
回答3:
rest of methods
import java.awt.*;
import java.lang.reflect.*;
import java.util.*;
import javax.swing.*;
/**
* Thread responsible for publishing changes to the Model. Sleeps for a defined
* amount of time, waits for no activity in the UI and then users invokeAndWait
* to publish changes.
*/
public class UpdateThread extends Thread {
private int sleepTime;
private int eqSleepTime;
private int threshhold;
private boolean updatesEnabled;
private Runnable publishRunnable;
private Runnable emptyRunnable;
private GeneratorThread generator;
private CTTableModel model;
private Map<?, ?> lastData;
private long notifyTime;
private long paintTime;
private int updateCount;
private boolean done;
public UpdateThread(GeneratorThread generator, CTTableModel model,
int sleepTime, int eqSleepTime, int threshhold) {
super();
setPriority(Thread.MIN_PRIORITY);
this.sleepTime = sleepTime;
this.eqSleepTime = eqSleepTime;
updatesEnabled = true;
this.threshhold = threshhold;
this.generator = generator;
this.model = model;
publishRunnable = new Runnable() {
// Runnable used to publish changes to the event dispatching thread
@Override
public void run() {
publishChangesOnEventDispatchingThread();
}
};
// Empty runnable, used to wait until the event dispatching thread
// has finished processing any pending events.
emptyRunnable = new Runnable() {
@Override
public void run() {
}
};
}
@Override
public void interrupt() {
done = true;
super.interrupt();
}
@Override
public void run() {
while (!isInterrupted() && !done) {
try {
sleep(sleepTime);
publishChanges();
} catch (InterruptedException ie) {
}
}
System.out.println("UpdateThread done");
}
/**
* Publishes changes on the event dispatching thread when the system isn't
* busy. This blocks the caller until the changes have been published.
*/
private void publishChanges() {
synchronized (this) {// Wait until the user isn't scrolling
while (!updatesEnabled) {
try {
wait();
} catch (InterruptedException ie) {
}
}
}
EventQueue queue = Toolkit.getDefaultToolkit().getSystemEventQueue();
// And wait until there are no pending events.
while (queue.peekEvent() != null) {
try {
sleep(eqSleepTime);
} catch (InterruptedException ie) {
}
}
final long start = System.currentTimeMillis();
try {
SwingUtilities.invokeAndWait(publishRunnable);
// publish the changes on the event dispatching thread
} catch (InterruptedException ie) {
} catch (InvocationTargetException ite) {
}
try {
// Wait until the system has completed processing of any events we
// triggered as part of publishing changes.
SwingUtilities.invokeAndWait(emptyRunnable);
} catch (InterruptedException ie) {
} catch (InvocationTargetException ite) {
}
final long end = System.currentTimeMillis();
try {// Update the display
SwingUtilities.invokeAndWait(new Runnable() {
@Override
public void run() {
Main.totalUpdateTime.setText("Total: "
+ Integer.toString((int) (end - start)));
Main.notifyTime.setText("Notify: "
+ Integer.toString((int) notifyTime));
Main.paintTime.setText("Paint: "
+ Integer.toString((int) paintTime));
Main.updateCount.setText("Updated: "
+ Integer.toString((int) updateCount));
}
});
} catch (InterruptedException ie) {
} catch (InvocationTargetException ite) {
}
}
/**
* Does the actual publishing of changes.
*/
private void publishChangesOnEventDispatchingThread() {
long start = System.currentTimeMillis();
model.setBatchUpdates(true);
Map<?, ?> data = generator.getData();
boolean notify = !(data.size() > threshhold ||
(lastData != null && lastData.size() + data.size() > threshhold));
updateCount = data.size();
if (lastData != null) {
updateCount += lastData.size();
}//Reset the data for the last set of changes we did, this forces the cells to change color.
if (lastData != null) {
publishData(lastData, true, notify);
Iterator<?> dataIterator = lastData.keySet().iterator();
while (dataIterator.hasNext()) {
DataChange.releaseDataChange((DataChange) dataIterator.next());
}
lastData.clear();
}
publishData(data, false, notify);// Publish the current set of data.
model.setBatchUpdates(false);
if (!notify) {
model.fireTableDataChanged();
}
lastData = data;
long end = System.currentTimeMillis();
notifyTime = (end - start);
start = System.currentTimeMillis();
RepaintManager.currentManager(null).paintDirtyRegions();
end = System.currentTimeMillis();
paintTime = (end - start);
}
/**
* Publish the passed in set of data.
*/
private void publishData(Map<?, ?> data, boolean negate, boolean notify) {
Iterator<?> dataIterator = data.keySet().iterator();
while (dataIterator.hasNext()) {
DataChange change = (DataChange) dataIterator.next();
Object value = data.get(change);
if (negate) {
value = new Integer(((Integer) value).intValue() * -1);
}
model.set(change.getData(), change.getColumn(), value, notify);
}
}
/**
* If enable is true, we are allowed to publish changes, otherwise we
* aren't.
*
* @param enable
*/
public void setUpdatesEnabled(boolean enable) {
synchronized (this) {
updatesEnabled = enable;
if (updatesEnabled) {
notify();
}
}
}
public boolean getUpdatesEnabled() {
return updatesEnabled;
}
}
.
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
/**
* VisibleTableModelEvent adds the method isVisible to test if the cell
* identified by the event is visible.
*/
public class VisibleTableModelEvent extends TableModelEvent {
private static final long serialVersionUID = 1L;
private Point tmpPoint;
// This implementation caches the information for one JTable, it is
// certainly possible to cache it for more than one should
// you have this need.
private boolean valid;
private int firstVisRow;
private int lastVisRow;
private int firstVisCol;
private int lastVisCol;
public VisibleTableModelEvent(TableModel source) {
super(source, 0, 0, 0, UPDATE);
tmpPoint = new Point();
}
/**
* Resets the underlying fields of the TableModelEvent. This assumes no ONE
* is going to cache the TableModelEvent.
*
* @param row
* @param col
*/
public void set(int row, int col) {
firstRow = row;
lastRow = row;
column = col;
}
/**
* Invoked to indicate the visible rows/columns need to be recalculated
* again.
*/
public void reset() {
valid = false;
}
public boolean isVisible(JTable table) {
if (!valid) {// Determine the visible region of the table.
Rectangle visRect = table.getVisibleRect();
tmpPoint.x = visRect.x;
tmpPoint.y = visRect.y;
firstVisCol = table.columnAtPoint(tmpPoint);
firstVisRow = table.rowAtPoint(tmpPoint);
tmpPoint.x += visRect.width;
tmpPoint.y += visRect.height;
lastVisCol = table.columnAtPoint(tmpPoint);
if (lastVisCol == -1) {
lastVisCol = table.getColumnCount() - 1;
}
if ((lastVisRow = table.rowAtPoint(tmpPoint)) == -1) {
lastVisRow = table.getRowCount();
}
valid = true;
}
return (firstRow >= firstVisRow && firstRow <= lastVisRow && column
>= firstVisCol && column <= lastVisCol);
}
}
来源：https://stackoverflow.com/questions/14987449/sluggish-performance-using-jtable-displaying-streaming-data