Creating Windows - Beginning Java 2 SDK - page 699

The static constant() method creates a Spring object from the three arguments that are the
minimum, preferred, and maximum values for the object. If all three values are equal, the object is
called a strut because its value is fixed at the common value you set for all three. There's an overloaded
version of the constant() method for creating struts:

Spring strut = Spring.constant(40); // min, pref, and max all set to 40

The Spring class also defines static methods that operate on Spring objects:

sum(Spring spr1, Spring spr2)

Returns a reference to a new Spring object that has
minimum, preferred, and maximum values that are the
sum of the corresponding values of the arguments.

minus (Spring spr) Returns a reference to a new Spring object with

minimum, preferred, and maximum values that are the
same magnitude as those of the argument but with
opposite signs.

max(Spring spr1, Spring spr2) Returns a reference to a new Spring object that has

minimum, preferred, and maximum values that are the
maximum of the corresponding values of the
arguments.

Setting Constraints for a Component
The setX() and setY() methods for a SpringLayout.Constraints object set the constraints for
the WEST and NORTH edges of the component respectively. For example:

Spring xSpring = Spring.constant(5,10,20); // Spring we'll use for X
Spring ySpring = Spring.constant(3,5,8); // Spring we'll use for Y
buttonConstr.setX(xSpring); // Set the WEST edge constraint
buttonConstr.setY(xSpring); // Set the NORTH edge constraint

The setX() method defines a constraint between the WEST edge of the container, and the WEST edge
of the component. Similarly, the setY() method defines a constraint between the NORTH edge of the
container and the NORTH edge of the component. This fixes the location of the component in relation to
the origin of the container.