Dragging and dropping into an empty table presents a unique challenge. When adhering to the proper steps:
TransferHandler
.setDragEnabled(true)
.You run the application and try to drag valid data into the table but it rejects the drop. What gives?
The reason is that the empty table (unlike an empty list or an empty tree) does not occupy any space in the scroll pane. The JTable
does not automatically stretch to fill the height of a JScrollPane
's viewport — it only takes up as much vertical room as needed for the rows that it contains. So, when you drag over the empty table, you are not actually over the table and the drop fails.
You can configure the table to allow drop anywhere in the view port by calling
JTable.setFillsViewportHeight(boolean)
. The default for this property is false to ensure backwards compatibility.
The following example, FillViewportHeightDemo
, allows you to experiment with dropping onto an empty table. The demo contains an empty table with five columns that has its drop mode set to insert rows and a drag source that provides five comma-delimited values that autoincrement.
FillViewportHeightDemo
using
Java™ Web Start (download JDK 6 or later). Alternatively, to compile and run the example yourself, consult the example index.You can examine the source for
, but the primary point to remember is that you should generally invoke FillViewportHeightDemo.java
setFillsViewportHeight(true)
on any table that will accept dropped data.