Re: Simple question about Java Methods

Eric Sosman <>
Mon, 18 Aug 2008 11:52:53 -0400
Danger_Duck wrote:

In paramaters, can I specify what type of String I want? For example,
can I do something like:

public void method1(static final String s) {
  //do something

I suppose my bigger question is how you specify a fixed value without
resorting to Java's ugly implementation of enumarations.

For instance, I want to have a class that will graph functions based
on type, but one of the parameters is "sin, square, sawtooth" etc.

Right now, I have declarators like 'public static final String sin =
"SinWave"; ' at the top of my class, and would like it so that the
constructor only accepts static final strings. Of course, he might use
such strings from different classes to my dismay, but at least I will
filter it out a bit.

     There is no such animal as a `static final String'.

     You're suffering from a confusion that has beset many others:
You've mixed up the reference with the thing referred to. The
things referred to are the String objects "SinWave" et al. These
String objects are not static, nor final, nor private, public,
protected, volatile, or anything else: They're just "out there"
in the JVM somewhere.

     The reference variable `sin', on the other hand, *is* static
and final and public. But `sin' is not "SinWave", `sin' refers
to "SinWave". The reference variable `sin' belongs to your class,
while the String object "SinWave" belongs to the JVM.

     If you can understand the difference between a telephone and
a telephone number, a house and a street address, or a person and
his name, you should be able to tell objects from references.

So am I able to get more specific about the parameters I want to take
in? My gut feeling is no since the above code looks atrocious, but I
would like to hear how one goes about such things in a simple manner
(again, without enumerations).

     Polymorphism can often substitute for selection. For example:

    public abstract class Wave {
        public abstract void graphMe();

        public static final Wave SIN = new Wave() {
            public void graphMe() { ... }

        public static final Wave SQUARE = new Wave() {
            public void graphMe() { ... }

    // Caller's code:

Unfortunately, if you ponder this long enough you'll discover that
you don't like it. (How do I know? You already said so!)


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