NamedArraylist class: Difference between revisions
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==Examples== | ==Examples== | ||
The following code | The following code shows some of the <var>NamedArraylist</var> methods: | ||
<p class="code">%narl is collection NamedArraylist of longstring | <p class="code">%narl is collection NamedArraylist of longstring | ||
%i is float | %i is float | ||
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should be used wherever their functionality may | should be used wherever their functionality may | ||
prove useful, without concern for performance (which will be quite good). | prove useful, without concern for performance (which will be quite good). | ||
==List of NamedArraylist methods== | ==List of NamedArraylist methods== | ||
The [[List of NamedArraylist methods|"List of NamedArraylist methods"]] shows all the class methods, with a brief description of each. | The [[List of NamedArraylist methods|"List of NamedArraylist methods"]] shows all the class methods, with a brief description of each. |
Revision as of 22:16, 12 November 2012
NamedArraylists can be thought of as traditional arrays 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.
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 Americans 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.
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).
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. |