JTable: Howto: Row color depending on value

[Michael Boeni]

Hi all

I would like to write a cell renderer that changes the background color of a row (or indivicual cells) depending on the value in one of the table columns. For example, if the value in column 'recursive' of a given row is 'true' then make the row (cell) backgroundd grey. if 'false' make white.

I ve been able to write a simple cell renderer:

public class colorTableCellRenderer  extends DefaultTableCellRenderer 
{
  java.awt.Color recursiveBG = new java.awt.Color(240, 240,240);
  
  public colorTableCellRenderer()
  {
    super();
  }
  public void setValue(Object value) 
  {
    String text = (String)value;
    this.setBackground(recursiveBG);
    this.setText(text);
  }
}

But i am lost on how to actually check the value of the other column so I can determine which color to choose.

Help is greately appreciated.

Cheers,
michael

[Joe Ess]

Take a look at the renderer examples in the Java Tutorial. The first example is similar to what you have. The second example is closer to what you want. Study the getTableCellRendererComponent method. It gives you a JTable reference which you can use to get the model so you can check your other columns, it gives you a row and a column so you know what cell you are rendering, and it returns the Component which will show up on the screen which you can color at will.

[Michael Boeni]

Thanks for the hint. I have now the following code:

public class colorTableCellRenderer extends JLabel implements TableCellRenderer 
{
  java.awt.Color recursiveBG = new java.awt.Color(240, 240,240);
  int recursiveColumn = 4;
  String recursiveID = null;
  
  public colorTableCellRenderer()
  {
    super();
  }
  public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
      {
        java.awt.Color recursiveColor = new java.awt.Color(240,240,240);
          String myVal = (String)value;
          this.setText(myVal);
 
          //          ipeTableModel myModel = (ipeTableModel)table.getModel();
          
 
          recursiveID = (String)table.getValueAt(row, recursiveColumn);
          System.out.println("Value: "+table.getValueAt(1,0));
          if(recursiveID != null) // row is not recursive
          {
            this.setBackground(Color.white);
            this.setForeground(Color.black);
            table.setSelectionBackground(Color.blue);
            table.setSelectionForeground(Color.white);
            }
          else // row IS recursive
          {
            this.setBackground(recursiveBG);
            this.setForeground(Color.red);
            table.setSelectionBackground(Color.blue);
            table.setSelectionForeground(Color.black);
          }
          return this;
      }
}

My current problem is that I don't know what class to extend? I want to set the cell background, how do i do this? The rest seems to work ok.

BTW, I don't have to get the model, I can extract the values from the table directly. Is there any disadvantage to this approach?

Cheers,
M.

[Michael Boeni]

Has evolved a bit more:

Hi

here is the current status:

public class colorTableCellRenderer extends DefaultTableCellRenderer 
{
  java.awt.Color recursiveBG = new java.awt.Color(240, 240,240);
  int recursiveColumn = 4;
  String recursiveID = null;
  
  public colorTableCellRenderer()
  {
    super();
  }
  public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
      {
        java.awt.Color recursiveColor = new java.awt.Color(240,240,240);
          String myVal = (String)value;
          this.setText(myVal);
 
          //          ipeTableModel myModel = (ipeTableModel)table.getModel();
          
 
          recursiveID = (String)table.getValueAt(row, recursiveColumn);
          if(recursiveID == null) // row is not recursive
          {
            this.setBackground(Color.white);
            this.setForeground(Color.black);
            table.setSelectionBackground(Color.blue);
            table.setSelectionForeground(Color.white);
            }
          else // row IS recursive
          {
            this.setBackground(recursiveBG);
            this.setForeground(Color.red);
            table.setSelectionBackground(Color.blue);
            table.setSelectionForeground(Color.black);
          }
            return this;
      }

I can now set the background color, thanks for pointing it out (DefaultTableCellRenderer did the trick)

Two more problems:
- I noticed that I need to compare to one more value which can be got from a method of the class that creates the table. I am not really sure on how to get a reference to it to be able to retrieve this value.

Example:
- i have a class 'connect' (main gui class) that defines the jtable we are talking about. In my renderer, I now need to be able to call a method from the 'connect' class in order to correctly determine row color..what is the best way to do this?

second: The cell i use the above renderer on does not show selections anymore (the color does not change...what is the problem here?
[ October 13, 2004: Message edited by: Michael Boeni ]

[Don Kiddick]

There are two main ways I would think of approaching this :

1: Pass a reference to Connect in the constructor of your renderer.
2. Pass the information you need, via the getValue method of your table model.

HTH.
D.

[Michael Boeni]

Thanks to all, most issues have been resolved now. The only thing that remains is that the cells that use my renderer do not change colors when selected anymore. Why could that be?

The current code is here:

public class colorTableCellRenderer extends DefaultTableCellRenderer
{
  java.awt.Color recursiveBG = new java.awt.Color(240, 240,240);
  int recursiveColumn = 4;
  String recursiveID = null;
  Connect connectRef = null;
 
  public colorTableCellRenderer(Connect connectRef)
  {
    super();
    this.connectRef = connectRef;
  }
  public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
      {
        java.awt.Color recursiveColor = new java.awt.Color(240,240,240);
        String myVal = (String)value;
        this.setText(myVal);
 
        recursiveID = (String)table.getValueAt(row, recursiveColumn);
        String selectedPerson = connectRef.getSelectedPersonPID();
        String sourceID = (String)table.getValueAt(row, 6);
 
        if(selectedPerson.equals(sourceID)) // row is not recursive
        {
          this.setBackground(Color.white);
         }
        else // row IS recursive
         {
          this.setBackground(recursiveBG);
          }
          return this;
      }
}

[Don Kiddick]

at the end of your method try

if (selected) {
setBackground(table.getSelectionBackground());
}

[Michael Boeni]

Thanks, Don. That did the trick...

Cheers,
michael