A TableLayout can specify certain columns as shrinkable or stretchable
by calling setColumnShrinkable() or
setColumnStretchable(). If marked as
shrinkable, the column width can be
shrunk to fit the table into its
parent object. If marked as
stretchable, it can expand in width to
fit any extra space. The total width
of the table is defined by its parent
container.
Have a look here, keep in mind that if your table fits nicely ( no space left to stretch) in the parent object, you would not see any changes no matter what value you put in.