WEST , and GridBagConstraints. Unless you specify at least one nonzero value for weightx or weighty , all the components clump together in the center of their container. Generally weights are specified with 0.0 and 1.0 as the extremes, with numbers in between used as necessary. Larger numbers indicate that the component's row or column should get more space. Similarly, each row's weight is related to the highest weighty specified for a component within that row.
Extra space tends to go toward the rightmost column and bottom row.
The next page discusses constraints in depth, in the context of explaining how the example applet works.