Re: Accessor Methods

From:

Hendrik Maryns <hendrik_maryns@despammed.com>

Newsgroups:

comp.lang.java.help

Date:

Thu, 18 May 2006 14:53:09 +0200

Message-ID:

<e4hqnl$d5v$1@newsserv.zdv.uni-tuebingen.de>

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Tobias Schr?er schreef:

Hi,

Allan M. Bruce schrieb:

<fightingbull06@yahoo.com> wrote in message
news:1147947898.806581.56840@i39g2000cwa.googlegroups.com...

[..]

public boolean setPosNum(int newValue)
{
    if (newValue < 0)
        return false; // error

    posNum = newValue;
    return true; // successful
}

[..]

I think it's better to throw a runtime exception than return a boolean
value. Negative values may not be set and should be avoided by the
programmer. If he does, an exception is thrown.
If the value that should be set comes from a user input, it's best to
check the input for validity in any way.

Indeed, that2"s what IllegalArgumentException is for. If you are
learning about accessor methods, you will probably also encounter the
function vs. procedure idea (setters are procedures, they do not return
a value), and the three different possibilities of handling wrong input:
do nothing (as above), throw an exception, or use preconditions (design
by contract). You have to decide for yourself which method is better in
which case, there is no golden rule (but of course there are personal
preferences...)

H.

- --
Hendrik Maryns

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