Re: How to specify a parameter
On Mar 15, 2:18 pm, "Luca D." <ldant...@gmail.com> wrote:
Hello!
When I create an instance of a class, I have to specify a direction,
which can be "Left" or "Right".
I thought about:
public class Object {
private String direction;
public Object(String direction) {
this.direction = direction;
}
}
Object o = new Object("Left"/"Right");
Otherwise:
public class Object {
private final int left = 0;
private final int right = 1;
private int direction;
public Object(int direction) {
this.direction = direction;
}
}
Object o = new Object(0/1);
In this case everyone must know that left = 0 and right = 1.
Is there a common way/design pattern to solve this kind of problem?
Thank you.
Hi,
Good question (shows lots of thought towards design that will save you
a heart ache in the long run if you continue to think of these things
up front rather than wait for a project to get large enough and
complex enough for these things to become significant).
If you are using a more recent version of Java (1.5 or higher) you can
use an enumeration (google java enumeration should give you everything
you need). 1.4 or earlier it was common to do something like declare a
public static final variables, something like:
public class Thingy {
public static final int LEFT = 0;
public static final int RIGHT = 1;
private int direction;
public Thingy(int initDirection) {
this.direction = initDirection;
}
}
Thingy thing = new Thingy(Thingy.LEFT);
Also, Josh Bloch had a very good book of idioms called Effective Java
that had an excellent section that described how to roll your own
enumerations in Java pre 1.5.
Have Fun,
John