again refer API
doc public GridLayout(int rows,
int cols,
int hgap,
int vgap)
Creates a grid layout with the specified number of rows and columns. All components in the layout are given equal size.
In addition, the horizontal and vertical gaps are set to the specified values. Horizontal gaps are placed at the left and right edges, and between each of the columns. Vertical gaps are placed at the top and bottom edges, and between each of the rows.
One, but not both, of rows and cols can be zero, which means that any number of objects can be placed in a row or in a column.
Parameters:
rows - the rows, with the value zero meaning any number of rows.
cols - the columns, with the value zero meaning any number of columns.
hgap - the horizontal gap.
vgap - the vertical gap