Group provides the basis for the two types of operations supported by GroupLayout: laying out components one after another (SequentialGroup) or aligned (ParallelGroup). Group and its subclasses have no public constructor; to create one use one of createSequentialGroup or createParallelGroup. Additionally, taking a Group created from one GroupLayout and using it with another will produce undefined results.

Various methods in Group and its subclasses allow you to explicitly specify the range. The arguments to these methods can take two forms, either a value greater than or equal to 0, or one of DEFAULT_SIZE or PREFERRED_SIZE. A value greater than or equal to 0 indicates a specific size. DEFAULT_SIZE indicates the corresponding size from the component should be used. For example, if DEFAULT_SIZE is passed as the minimum size argument, the minimum size is obtained from invoking getMinimumSize on the component. Likewise, PREFERRED_SIZE indicates the value from getPreferredSize should be used. The following example adds myComponent to group with specific values for the range. That is, the minimum is explicitly specified as 100, preferred as 200, and maximum as 300.

   group.addComponent(myComponent, 100, 200, 300);
 

The following example adds myComponent to group using a combination of the forms. The minimum size is forced to be the same as the preferred size, the preferred size is determined by using myComponent.getPreferredSize and the maximum is determined by invoking getMaximumSize on the component.

   group.addComponent(myComponent, GroupLayout.PREFERRED_SIZE,
             GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE);
 

Unless otherwise specified all the methods of Group and its subclasses that allow you to specify a range throw an IllegalArgumentException if passed an invalid range. An invalid range is one in which any of the values are < 0 and not one of PREFERRED_SIZE or DEFAULT_SIZE, or the following is not met (for specific values): min <= pref <= max.

Similarly any methods that take a Component throw a NullPointerException if passed null and any methods that take a Group throw an IllegalArgumentException if passed null.

since	1.6
See also	createSequentialGroup, createParallelGroup