Question

I have a JTable in my application. I have a custom renderer setup on the table (a JTextArea, with line-wrapping enabled) which allows for multi-line content. The contents of the JTable cells are expected to overflow the bounds of the cell in some cases. I want to do the following:

Instead of making the user drag the row border to resize the cell, I want the user to be able to double-click the row border, so when I detect this, I can automatically resize the height of the cell (height of the row) to show the entire contents of the cell.

My question is, what is the best way to detect a double-click on the row border? I have gotten this to work by setting up a MouseListener on the JTable with a mouseClicked method that looks like this:

public class MouseButtonInputListener extends MouseInputAdapter
{
    private JTable fTable;

    public MouseButtonInputListener(JTable parentTable)
    {
       fTable = parentTable;
    } 

    @Override
    public void mouseClicked(MouseEvent e)
    {

        // Some pre-processing here...

        if(e.getClickCount() == 2 && 
           fTable.getCursor().getType() == Cursor.N_RESIZE_CURSOR)
        {
            // Auto-adjust row height to fit contents...            
        }

    }
}

While this works, i’m not very happy with the line:

fTable.getCursor().getType() == Cursor.N_RESIZE_CURSOR

Any suggestions on a better way to do this? Is the above a reliable approach on all platforms?

Answer 1

After some searching online, I found the following page:

http://java.sun.com/products/jlf/ed2/book/HIG.Behavior.html

amongst other things, it specifies mouse cursor behavior under different circumstances. According to the section on “Pointer Feedback”, the cursor switches between a N_RESIZE_CURSOR and S_RESIZE_CURSOR depending on whether it is the upper or lower boundary of a component that is being hovered over. It’s interesting to note that on 2 out of 3 platforms (Mac and Windows), these cursors are exactly the same. Anyway, it follows that my code should therefore read:

@Override
public void mouseClicked(MouseEvent e)
{
    // Some pre-processing here. Determine row at mouse click location
    int cursorType = fTable.getCursor().getType();
    if(e.getClickCount == 2 && 
      (cursorType == Cursor.N_RESIZE_CURSOR || cursorType == CURSOR.S_RESIZE_CURSOR))
    {
        // Resize row appropriately.
    }
}

This will work on all platforms. Thanks for the inputs and comments everyone.