Re: define a set of constant

Daniel Pitts <>
Wed, 01 Sep 2010 10:39:29 -0700
On 8/31/2010 12:25 PM, markspace wrote:

On 8/31/2010 10:03 AM, a wrote:

The point for doing this is to limit the options for the user to input
calling the method.
It is very similiar to HasHorizontalAlignment and
HasHorizontalAlignment.HorizontalAlignment, but I dont understand how it

They really don't work.

SwingConstants just holds a bunch of ints. You example just uses
Strings. Neither one of these by their nature actually limits the
options for user of the method. It was a dumb idea for Swing to do
things this way.

It's better to use a specific type that you created to limit the options
for the user of the method.

public class MyOptions {
public static final MyOption OPTION1 = new MyOption( "Option 1" );
public static final MyOption OPTION2 = new MyOption( "Option 2" );

private final String option;

private MyOption( String s ) {
option = s;

public String toString() {
return option;

is the basic pattern. Note the public (but final) static fields and the
private constructor. Those are key. Enums will do some of this
auto-magically for you.

Now you can restrict a method parameter to just OPTION1 or OPTION2.

public void someMethod( MyOptions opt ) {

Since only you have control of your type MyOptions class, only you can
add more fields for a user to pass to someMethod().

More specifically, he should use a MyOption enum instead:

public enum MyOption {

public class SomeOtherClass {
    public void method(MyOption option) {
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