Re: Unchecked call to compareTo

From:

Lew <lew@nowhere.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 02 Jan 2007 18:42:31 -0500

Message-ID:

<h5GdnfmnFqt6cAfYnZ2dnUVZ_oannZ2d@comcast.com>

Russell Wallace wrote:

Just plain old Objects. The idea is that there's data in rows and
columns, each column may contain BigDecimals, Strings, Dates or
whatever, and the intent is to sort records by the values in the
currently selected column. So in:

int compare(Record a, Record b) {
Comparable ca = (Comparable<?>) get(a);
Comparable cb = (Comparable<?>) get(b);
return ca.compareTo(cb);
}

ca represents record a's value in the currently selected column, ditto
cb for record b. ca and cb may be BigDecimal, String or whatever, but
they are guarenteed to be the same type (though I don't know how or if I
can tell the compiler that).

Now you are definitely in the "<T ...> compare( T, T )" world.

How about you do the get outside the method and pass the comparables into the
method, so that the method is responsible for only one task, not both
extraction and comparison?

Then you don't even need the comparison method, since compareTo already works.

Object oa = get( a );
Object ob = get( b );
if ( oa.compareTo( ob ) ) { ... } // if ( get(a).compareTo( get(b) ) ) ...

- Lew