jtable - Page 6 - Tech Tips & Tricks

Create Pushable Button Table Headers In JTable

November 19, 2009 by blogmeister·3 Comments

Swing components in Java are very flexible. You can change the table header of a JTable to become a JButton to display the headers as clickable. The class PushtableTableHeader does just that. See the code below.

public class PushableTableHeader extends JPanel {
    public PushableTableHeader(TableColumn column, JTableHeader header) {
        setLayout(new BorderLayout());
        ButtonHeaderRenderer renderer = new ButtonHeaderRenderer();
        column.setHeaderRenderer(renderer);
        header.addMouseListener(new HeaderListener(header, renderer));
    }
    public class HeaderListener extends MouseAdapter {
        JTableHeader header;
        ButtonHeaderRenderer renderer;
        HeaderListener(JTableHeader header, ButtonHeaderRenderer renderer) {
            this.header   = header;
            this.renderer = renderer;
        }
        @Override
        public void mousePressed(MouseEvent e) {
            int col = header.columnAtPoint(e.getPoint());
            renderer.setPressedColumn(col);
            header.repaint();
        }
        @Override
        public void mouseReleased(MouseEvent e) {
            int col = header.columnAtPoint(e.getPoint());
            renderer.setPressedColumn(-1);
            header.repaint();
        }
    }
    class ButtonHeaderRenderer extends JButton implements TableCellRenderer {
        int pushedColumn;
        public ButtonHeaderRenderer() {
            pushedColumn   = -1;
            setMargin(new Insets(0,0,0,0));
        }
        @Override
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
            setText((value ==null) ? "" : value.toString());
            boolean isPressed = (column == pushedColumn);
            getModel().setPressed(isPressed);
            getModel().setArmed(isPressed);
            return this;
        }
        public void setPressedColumn(int col) {
            pushedColumn = col;
        }
    }
}

public class PushableTableHeader extends JPanel {

public PushableTableHeader(TableColumn column, JTableHeader header) {

setLayout(new BorderLayout());

ButtonHeaderRenderer renderer = new ButtonHeaderRenderer();

column.setHeaderRenderer(renderer);

header.addMouseListener(new HeaderListener(header, renderer));

}

public class HeaderListener extends MouseAdapter {

JTableHeader header;

ButtonHeaderRenderer renderer;

HeaderListener(JTableHeader header, ButtonHeaderRenderer renderer) {

this.header = header;

this.renderer = renderer;

}

@Override

public void mousePressed(MouseEvent e) {

int col = header.columnAtPoint(e.getPoint());

renderer.setPressedColumn(col);

header.repaint();

}

@Override

public void mouseReleased(MouseEvent e) {

int col = header.columnAtPoint(e.getPoint());

renderer.setPressedColumn(-1);

header.repaint();

}

class ButtonHeaderRenderer extends JButton implements TableCellRenderer {

int pushedColumn;

public ButtonHeaderRenderer() {

pushedColumn = -1;

setMargin(new Insets(0,0,0,0));

}

@Override

public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {

setText((value ==null) ? "" : value.toString());

boolean isPressed = (column == pushedColumn);

getModel().setPressed(isPressed);

getModel().setArmed(isPressed);

return this;

}

public void setPressedColumn(int col) {

pushedColumn = col;

}

To use the class, you can do it like this.

new PushableTableHeader(jTable1.getColumn("MY_COLUMN_NAME"), jTable1.getTableHeader());

1	new PushableTableHeader(jTable1.getColumn("MY_COLUMN_NAME"), jTable1.getTableHeader());

I purposely placed this in a class so that I could isolate only table columns that need to have a pushable button as its header.

Auto Resize JTable Columns

November 15, 2009 by blogmeister·8 Comments

This class auto resizes columns of a JTable, maximizing any non-used width columns and transferring those extra widths to other columns. This way, a column with a JCheckBox will have a width almost equal to that of a JCheckBox‘s width. The class TableColumnResizer contains one static method and you can pass the JTable object as the parameter. The code does the rest.

To use the method, do this:

TableColumnResizer.adjustColumnPreferredWidths(myJTableObject);

1	TableColumnResizer.adjustColumnPreferredWidths(myJTableObject);

Here is the code of the TableColumnResizer class.

public class TableColumnResizer {
    public static void adjustColumnPreferredWidths(JTable table) {
        if (table == null || table.getColumnCount() == 0) {
            return;
        }
        // strategy - get max width for cells in column and
        // make that the preferred width
        TableColumnModel columnModel = table.getColumnModel();
        for (int col = 0; col < table.getColumnCount(); col++) {
            try {
                int maxwidth = 0;
                for (int row = 0; row < table.getRowCount(); row++) {
                    TableCellRenderer rend = table.getCellRenderer(row, col);
                    Object value = table.getValueAt(row, col);
                    Component comp = rend.getTableCellRendererComponent(table, value, false, false, row, col);
                    maxwidth = Math.max(comp.getPreferredSize().width, maxwidth);
                }
                TableColumn column = columnModel.getColumn(col);
                TableCellRenderer headerRenderer = column.getHeaderRenderer();
                if (headerRenderer == null) {
                    headerRenderer = table.getTableHeader().getDefaultRenderer();
                }
                Object headerValue = column.getHeaderValue();
                Component headerComp = headerRenderer.getTableCellRendererComponent(table, headerValue, false, false, 0, col);
                maxwidth = Math.max(maxwidth, headerComp.getPreferredSize().width);
                column.setPreferredWidth(maxwidth);
            } catch (Exception e) {
            }
        }
    }
    public static void adjustColumnPreferredWidths(JTable table, int columnIndex) {
        if (table == null || table.getColumnCount() == 0) {
            return;
        }
        // strategy - get max width for cells in column and
        // make that the preferred width
        TableColumnModel columnModel = table.getColumnModel();
        try {
            int maxwidth = 0;
            for (int row = 0; row < table.getRowCount(); row++) {
                TableCellRenderer rend = table.getCellRenderer(row, columnIndex);
                Object value = table.getValueAt(row, columnIndex);
                Component comp = rend.getTableCellRendererComponent(table, value, false, false, row, columnIndex);
                maxwidth = Math.max(comp.getPreferredSize().width, maxwidth);
            }
            TableColumn column = columnModel.getColumn(columnIndex);
            TableCellRenderer headerRenderer = column.getHeaderRenderer();
            if (headerRenderer == null) {
                headerRenderer = table.getTableHeader().getDefaultRenderer();
            }
            Object headerValue = column.getHeaderValue();
            Component headerComp = headerRenderer.getTableCellRendererComponent(table, headerValue, false, false, 0, columnIndex);
            maxwidth = Math.max(maxwidth, headerComp.getPreferredSize().width);
            column.setPreferredWidth(maxwidth);
        } catch (Exception e) { }
    }
}

public class TableColumnResizer {

public static void adjustColumnPreferredWidths(JTable table) {

if (table == null || table.getColumnCount() == 0) {

return;

}

// strategy - get max width for cells in column and

// make that the preferred width

TableColumnModel columnModel = table.getColumnModel();

for (int col = 0; col < table.getColumnCount(); col++) {

try {

int maxwidth = 0;

for (int row = 0; row < table.getRowCount(); row++) {

TableCellRenderer rend = table.getCellRenderer(row, col);

Object value = table.getValueAt(row, col);

Component comp = rend.getTableCellRendererComponent(table, value, false, false, row, col);

maxwidth = Math.max(comp.getPreferredSize().width, maxwidth);

}

TableColumn column = columnModel.getColumn(col);

TableCellRenderer headerRenderer = column.getHeaderRenderer();

if (headerRenderer == null) {

headerRenderer = table.getTableHeader().getDefaultRenderer();

}

Object headerValue = column.getHeaderValue();

Component headerComp = headerRenderer.getTableCellRendererComponent(table, headerValue, false, false, 0, col);

maxwidth = Math.max(maxwidth, headerComp.getPreferredSize().width);

column.setPreferredWidth(maxwidth);

} catch (Exception e) {

}

public static void adjustColumnPreferredWidths(JTable table, int columnIndex) {

if (table == null || table.getColumnCount() == 0) {

return;

}

// strategy - get max width for cells in column and

// make that the preferred width

TableColumnModel columnModel = table.getColumnModel();

try {

int maxwidth = 0;

for (int row = 0; row < table.getRowCount(); row++) {

TableCellRenderer rend = table.getCellRenderer(row, columnIndex);

Object value = table.getValueAt(row, columnIndex);

Component comp = rend.getTableCellRendererComponent(table, value, false, false, row, columnIndex);

maxwidth = Math.max(comp.getPreferredSize().width, maxwidth);

}

TableColumn column = columnModel.getColumn(columnIndex);

TableCellRenderer headerRenderer = column.getHeaderRenderer();

if (headerRenderer == null) {

headerRenderer = table.getTableHeader().getDefaultRenderer();

}

Object headerValue = column.getHeaderValue();

Component headerComp = headerRenderer.getTableCellRendererComponent(table, headerValue, false, false, 0, columnIndex);

maxwidth = Math.max(maxwidth, headerComp.getPreferredSize().width);

column.setPreferredWidth(maxwidth);

} catch (Exception e) { }

}

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Tag: jtable

Create Pushable Button Table Headers In JTable

Auto Resize JTable Columns

Display ToolTip in JTable Cell If Text Is Truncated