NamedArraylist class

From m204wiki
Jump to: navigation, search

A NamedArraylist can be thought of as a traditional array with no bounds but with identifying subscripts that can be arbitrary strings rather than numbers.

About the GenericNamedArraylist class

The NamedArraylist class extends the system GenericNamedArraylist class, so many of the methods available in the NamedArraylist class are documented as belonging to the GenericNamedArraylist class. Any method available in the GenericNamedArraylist class is also available in the NamedArraylist class. The other classes that extend the GenericNamedArraylist class are the FloatNamedArraylist class and the UnicodeNamedArraylist class.

Looking up an item in a NamedArraylist by its name is only slightly (possibly immeasurably) more CPU intensive than looking up the item by number, either in a NamedArraylist or in an Arraylist. NamedArraylist items will also take up a bit more space in CCATEMP than Arraylist items — the extra space required to hold the names. Usually, this overhead should be minor.

Because of their relatively low extra overhead, NamedArraylists should be used wherever their functionality may prove useful, without concern for performance (which will be quite good).

Examples

  • The following code shows some of the NamedArraylist methods:

    %narl is collection NamedArraylist of longstring %i is float %narl = new %narl:useDefault = true %narl('Idle') = 'Eric' %narl('Cleese') = 'John' %narl('Gilliam') = 'Terry' %narl('Pallin') = 'Michael' %narl('Chapman') = 'Graham' Print 'The American''s first name is ' %narl('Gilliam') print '*** Completely different:' for %i from 1 to %narl:count print %narl:itemByNumber(%i) and %narl:nameByNumber(%i) end for

    This code prints:

    The American's first name is Terry *** Completely different: Graham Chapman John Cleese Terry Gilliam Eric Idle Michael Pallin

    Note: The items are kept in EBCDIC order by their name. This is always the case for NamedArraylist items.

  • For another example, suppose there is a Recordset object in a file where field ProductId has a product ID and field Quantity has the number of items with that ID. The product IDs are ten-character alphanumeric IDs, so they cannot be used as numeric subscripts. Some records may have the same ProductId as others. NamedArraylists provide an ideal way of getting the total quantity of each item in the Recordset:

    %quantity is collection NamedArraylist of float ... %quantity = new %quantity:useDefault = true for each record in %recset  %quantity(productId) = %quantity(productId) + quantity end for for %i from 1 to %quantity:count print %quantity:nameByNumber(%i) and -  %quantity:itemByNumber(%i) end for

    Because UseDefault is set to True, the first reference to a %quantity item for a given ProductId will return the default value of 0. The value of the Quantity field is added to this 0, and the total is stored under the product ID.

    Subsequent requests for the same product ID will return the current running total for that product.

List of NamedArraylist methods

The List of NamedArraylist methods shows all the class methods, with a brief description of each.

See also

List of FloatNamedArraylist methods For a list of all methods in the FloatNamedArraylist class, with a brief description of each.
List of UnicodeNamedArraylist methods For a list of all methods in the UnicodeNamedArraylist class, with a brief description of each.
Collections For background information about collections and Arraylists and about declaring Arraylist object variables.
Coding considerations for collections For tips on using collections.