I am putting a JTable into a JScrollPane
But When I set JTable Auto Resizeable, then it won't have horizontal scroll bar.
if I set AUTO_RESIZE_OFF, then the Jtable won't fill the width of its container when the column width is not big enough.
So how can I do this:
when the table is not wide enough, expand to fill its container width
when the table is wide enough, make it scrollable.
Thanks
You need to customize the behaviour of the Scrollable interface.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
public class TableHorizontal extends JFrame
{
public TableHorizontal()
{
final JTable table = new JTable(10, 5)
{
public boolean getScrollableTracksViewportWidth()
{
return getPreferredSize().width < getParent().getWidth();
}
};
table.setAutoResizeMode( JTable.AUTO_RESIZE_OFF );
final JScrollPane scrollPane = new JScrollPane( table );
getContentPane().add( scrollPane );
}
public static void main(String[] args)
{
TableHorizontal frame = new TableHorizontal();
frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
frame.pack();
frame.setSize(400, 300);
frame.setVisible(true);
}
}
The above code basically sizes the component at its preferred size or the viewport size, whichever is greater.
If for some reason customising JTable is not an option (e.g. it might be created in third-party code), you can achieve the same result by setting it to toggle between two different JTable AUTO_RESIZE modes whenever the containing viewport is resized, e.g.:
jTable.getParent().addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(final ComponentEvent e) {
if (jTable.getPreferredSize().width < jTable.getParent().getWidth()) {
jTable.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
} else {
jTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
}
}
});
I found that all that is needed is to include
table = new JTable(model);
// this enables horizontal scroll bar
table.setAutoResizeMode( JTable.AUTO_RESIZE_OFF );
and then when the required viewport width and height have been calculated, include
frame.getContentPane().add(new JScrollPane(table))
table.setPreferredScrollableViewportSize(new Dimension(width,height));
If you set the Layout of its container to BorderLayout with a BorderLayout.CENTER layout constraint, then the JTable will auto resize to fit its container.
If you want to make a component scrollable, you can wrap the JTable with a JScrollPane.
setLayout(new BorderLayout());
add(new JScrollPane(new JTable()), BorderLayout.CENTER);
Related
i been working on some bigger project lately but couldn't figure it out why JScrollPane wouldn't work. I have never used it before and I read many solved problems about it on stackOverflow and other programming forums but non of the code were looking similar to mine to help me implement my method.
this is new project i made to make it short and show some examples.
Red colour is main panel that will contain another panel/JScrollPane inside that will be colour black
and i would like to make this Jpanel with colour black to be scrollable and hold any number of that white JPanels that might be from 0 to a 100+
public class ScrollablePane {
private JFrame frame;
private JPanel panelCopy;
private JPanel panel;
private JPanel container;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ScrollablePane window = new ScrollablePane();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public ScrollablePane() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
panel = new JPanel();
panel.setBackground(Color.RED);
panel.setBounds(0, 0, 434, 261);
frame.getContentPane().add(panel);
panel.setLayout(null);
container = new JPanel();
container.setBackground(Color.BLACK);
container.setBounds(10, 10, 414, 241);
container.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));
panel.add(container);
for(int i = 0; i < 20; i++) {
if(i > 0) {
panelCopy = new JPanel();
panelCopy.setPreferredSize(new Dimension(400, 40));
container.add(panelCopy);
}
}
}
}
if you want to use a JScrollPane, then your code actually needs to use a JScrollPane. The code you posted doesn't even create a JScrollPane.
If you want the panels to display vertically then don't use a FlowLayout. The FlowLayout is a horizontal layout. You could use a BoxLayout or a GridBagLayout.
Why do you create the "panel" variable and add it the the content pane? The content pane of the frame already is a JPanel that uses a BorderLayout. There is no need to add another panel
Don't use a null layout!!! Swing was designed to be used with layout managers. Scrolling won't work if the panel added to the scroll pane uses a null layout.
So in your case the basic logic might be something like:
Box container = Box.createVerticalBox();
// add you child panels to the container.
JPanel wrapper = new JPanel( new BorderLayout() );
wrapper.add(container, BorderLayout.PAGE_START);
JScrollPane scrollPane = new JScrollPane(wrapper);
frame.add(scrollPane, BorderLayout.CENTER);
Note the "wrapper" panel is used to prevent the panels from expanding in size when the scroll pane is larger then the preferred size of the "container" panel.
Try:
//JScrollPane scrollPane = new JScrollPane(wrapper);
JScrollPane scrollPane = new JScrollPane(container);
to see the different result.
When I run the program, the JPanel is not visible. It works without the JScrollPane though. This is driving me crazy! Before, I had it using a Canvas and a ScrollPane. Note that FlowchartPanel extends JPanel.
public class Window extends JFrame{
private FlowchartPanel panel; // contains all the main graphics
private JScrollPane scrollpane; // contains panel
private int canvasWidth, canvasHeight; // the width and height of the canvas object in pixels
private Flowchart flowchart; // the flowchart object
public Window(Flowchart flowchart) {
super();
canvasWidth = 900;
canvasHeight = 700;
this.flowchart = flowchart;
flowchart.setWidth(canvasWidth);
flowchart.setHeight(canvasHeight);
setDefaultCloseOperation(EXIT_ON_CLOSE);
panel = new FlowchartPanel(flowchart);
panel.setPreferredSize(new Dimension(canvasWidth, canvasHeight));
scrollpane = new JScrollPane();
scrollpane.setPreferredSize(new Dimension(canvasWidth, canvasHeight));
scrollpane.add(panel);
add(scrollpane);
//add(panel);
pack();
}
}
Don't add components directly to a JScrollPane.
The component needs to be added to the JViewPort of the JScrollPane
The easiest way to do this is to use:
JScrollPane scrollPane = new JScrollPane( panel );
Another way is to replace (add) the component in the viewport is to use:
scrollPane.setViewportView( panel );
panel.setPreferredSize(new Dimension(canvasWidth, canvasHeight));
Don't set the preferred size of a component. Every Swing component is responsible for determining its own preferred size. Instead override the getPreferredSize() method of your custom panel to return the size. This way as the custom painting changes, you can dynamically change the preferred size as required.
I am using Miglayout to define a layout for my program. The problem is the JScrollPane prevents the JButton shrinking below its preferred size. The minimum, preferred, and maximum widths for the JButton are set like this, "w 300:600:900" //min:pref:max.
What is the best way to fix this problem?
SSSCE
import java.awt.*;
import javax.swing.*;
import net.miginfocom.swing.MigLayout;
public class ButLay extends JFrame {
private ButLay() {
super("Button Layout");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new MigLayout("", "grow", "grow"));
createPanel();
setSize(800, 200);
setVisible(true);
}
JPanel panel = new JPanel(new MigLayout("", "grow", "grow"));
JScrollPane scroll;
JButton button = new JButton("Button");
private void createPanel() {
panel.add(button, "gapleft 100, align right, w 300:600:900, south");
scroll = new JScrollPane(panel);
getContentPane().add(scroll, "grow");
}
public static void main(String[] args) {
new ButLay();
}
}
The default behaviour of a JScrollPane is to display the component in the scroll pane at its preferred size so that the scrollbars can appear as required.
If you want to change the behaviour then you can try to implement the Scrollable interface on your panel. You might be able to override the getScrollableTracksViewportWidth() method to return true. Now your panel should resize as the viewport of the scrollpane resizes. However using this approach your won't get a scrollbar if you make the viewport too small.
If you want the scrollbar in the above situation, then you may also need to override the getPreferredSize() method to return the minimum size when the preferredSize is greater than the size of the viewport.
You can also check out Scrollable Panel which implements the Scrollable interface for you and allows you to customize the behaviour with some convenience methods.
I got a JTable, which i applied AUTO_RESIZE_LAST_COLUMN to. It auto resizes last column when i drag the columns left or right..
However, the JTable are attached to a JPanel with a BorderLayout manager. When i resize the JFrame, the JPanel resize, and since the JTable fills the JPanel, the JTable resizes too. But when i resize the JFrame, the AUTO_RESIZE_LAST_COLUMN doesnt works, but instead it resizes all the columns.
I want it to only auto_resize the last column, when the JFrame changes size, instead of resize all columns.
code:
import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;
public class JTableResize extends JFrame {
private JTable table;
private JPanel panel;
private JScrollPane pane;
DefaultTableModel model = new DefaultTableModel();
public JTableResize() {
super("JTable - Resize Problem");
setLayout(new BorderLayout());
panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.setBackground(Color.red);
add(panel, BorderLayout.CENTER);
table = new JTable(model);
//panel.add(table);
model.addColumn("Resize");
model.addColumn("Problem");
model.addColumn("........");
model.addColumn("This should resize");
pane = new JScrollPane(table);
panel.add(pane);
//this is supposed to resize last column.. It works when you drag in the columns, but not when frame are resized
table.setAutoResizeMode(JTable.AUTO_RESIZE_LAST_COLUMN);
table.getTableHeader().setReorderingAllowed(false);
table.setShowVerticalLines(false);
for (int i = 0; i <= 50; i++) {
model.addRow(new Object[] {i, i, i, i});
}
}
public static void main(String[] args) {
JTableResize jtr = new JTableResize();
jtr.setSize(500, 500);
jtr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jtr.setVisible(true);
}
}
Check out the API documentation from the doLayout() method of JTable.
Before the layout begins the method gets the resizingColumn of the tableHeader. When the method is called as a result of the resizing of an enclosing window, the resizingColumn is null. This means that resizing has taken place "outside" the JTable and the change - or "delta" - should be distributed to all of the columns regardless of this JTable's automatic resize mode.
So this behaviour is not support by default.
Overriding the doLayout() method of the JTable and setting the "resizing column" to the last column seems to do the trick:
#Override
public void doLayout()
{
if (tableHeader != null)
{
TableColumn resizingColumn = tableHeader.getResizingColumn();
// Viewport size changed. Increase last columns width
if (resizingColumn == null)
{
TableColumnModel tcm = getColumnModel();
int lastColumn = tcm.getColumnCount() - 1;
tableHeader.setResizingColumn( tcm.getColumn( lastColumn ) ) ;
}
}
super.doLayout();
}
I have a main Panel and I'm adding components dynamically into that one.
Main Panel has GridLayout limited to 3 columns and 0 rows (0 rows will allow rows to grow infinitely), but the problem is that I want all components to have fixed size or component's preferred size.
I can use other layout if it meets my requirements... but for now only GridLayout allows me to limit columns to 3...
I forgot to mention, Main Panel is added into JScrollpane, so I can scroll vertically.
One way to to do this is to use JPanels. GridLayout will stretch your components, but if you wrap the component in a JPanel, then the JPanel gets stretched. And since JPanel uses FlowLayout, which does not stretch components, your components remain at their preferred size.
Here's an example using JButton. Notice how I add them to a (new) JPanel each loop, then I add the panel to the grid layout.
import javax.swing.*;
public class GridLayout {
public static void main( String[] args ) {
SwingUtilities.invokeLater( new Runnable() {
public void run() {
JFrame frame = new JFrame();
frame.setLayout( new java.awt.GridLayout( 0, 3 ) );
for( int i = 0; i < 21; i++ ) {
JPanel panel = new JPanel(); // Make a new panel
JButton button = new JButton( "Button "+i );
panel.add( button ); // add the button to the panel...
frame.add( panel ); // ...then add the panel to the layout
}
frame.pack();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
} );
}
}