Show tooltips in JTable only when column is cut off

Question

how can I implement a tooltip which shows me for each cell a tip when the value is too long?

I just have a table renderer which colors me some cell. So I think the easiest way is to implement the metod in it.

public class ColorRenderer extends DefaultTableCellRenderer {

      final int STATUS_COL = 7;

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

      Component component = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);

     int modelIndex = table.convertRowIndexToModel(row);
      String type = (String) table.getModel().getValueAt(modelIndex, 7);

      if ("".endsWith(type)) {
      component.setBackground(table.getBackground());
      component.setForeground(table.getForeground());


      } else {
      component.setBackground(Color.RED);
      component.setForeground(Color.WHITE);

      }
      if (isSelected) {
      setBackground(table.getSelectionBackground());
      setForeground(table.getSelectionForeground());

      }

      return component;
      }

}

Thank you in advance.

Answer 1

Start by overriding the getToolTipText(MouseEvent) event of the JTable.

public String getToolTipText(MouseEvent e) {
    String toolTipText = null;

Get the cell coordinates for the given mouse location...

Point p = e.getPoint(); // MouseEvent
int col = columnAtPoint(p);
int row = rowAtPoint(p);

Get the cells current size, this way we know what the current constraints are...

Rectangle bounds = getCellRect(row, col, false);

Get the renderer for the cell, based on the current value for the cell from the model...

Object value = getValueAt(row, col);
Component comp = prepareRenderer(getCellRenderer(row, col), row, col);

Compare the preferred size of the renderer component against the cell size...

if (comp.getPreferredSize().width > bounds.width) {
    toolTipText = comp.getToolTipText();
}

Return the tool tip...

    return toolTipText;
}

Answer 2

Solution:

JTable auditTable = new JTable(){

     public String getToolTipText(MouseEvent e) {

                    String toolTipText = null;
                    Point p = e.getPoint(); // MouseEvent
                    int col = columnAtPoint(p);
                    int row = rowAtPoint(p);
                    Component comp = prepareRenderer(getCellRenderer(row, col), row, col);

                    Rectangle bounds = getCellRect(row, col, false);


                    try {
                        //comment row, exclude heading
                      if (comp.getPreferredSize().width > bounds.width) {
                            toolTipText = getValueAt(row, col).toString();
                        }
                    } catch (RuntimeException e1) {
                        //catch null pointer exception if mouse is over an empty line
                    }
                    return toolTipText;

                   }
        };

Answer 3

By default, the tool tip text displayed for a table cell is determined by the cell's renderer. However, sometimes it can be simpler to specify tool tip text by overriding JTable's implementation of the getToolTipText(MouseEvent) method, so you can add

setToolTipText(...);

in the getTableCellRendererComponent method with the real cell value inside so you get

Component component = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);

     int modelIndex = table.convertRowIndexToModel(row);
      String type = (String) table.getModel().getValueAt(modelIndex, 7);

      if ("".endsWith(type)) {
      component.setBackground(table.getBackground());
      component.setForeground(table.getForeground());


      } else {
      component.setBackground(Color.RED);
      component.setForeground(Color.WHITE);

      }
      if (isSelected) {
      setBackground(table.getSelectionBackground());
      setForeground(table.getSelectionForeground());

      }
      setToolTipText(...);
      return component;
      }