SubsetNew (Arraylist function): Difference between revisions

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<tr><th>selectionCriterion</th>
<tr><th>selectionCriterion</th>
<td>A <var>[[SelectionCriterion class|SelectionCriterion]]</var> object, which is a relational expression that is applied to an <var class="term">al</var> item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.
<td>A <var>[[SelectionCriterion class|SelectionCriterion]]</var> object, which is a relational expression that is applied to an <var class="term">al</var> item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.
<p>For example, <code>GT(this, -11)</code> is the criterion <code>this > -11</code>, where <code>this</code> is an identity function that simply returns the item's value. The items that satisfy this expression populate the <var>Arraylist</var> that <var>SubsetNew</var> returns.</p>
<p>For example, <code>GT(this, -11)</code> is the criterion <code>this > -11</code>, where <var>this</var> is an identity function value that simply returns the item's value. The items that satisfy this expression populate the <var>Arraylist</var> that <var>SubsetNew</var> returns.</p>
<p>The function in the criterion is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the <var class="term">al</var> declaration and that returns a numeric or string value. This is described further in [[SelectionCriterion class#Specifying a SelectionCriterion's parameters|"Specifying a SelectionCriterion's parameters"]].</p></td></tr>
<p>The function in the criterion is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the <var class="term">al</var> declaration and that returns a numeric or string value. This is described further in [[SelectionCriterion class#Specifying a SelectionCriterion's parameters|"Specifying a SelectionCriterion's parameters"]].</p></td></tr>
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Revision as of 17:50, 3 May 2011

Return all matching Arraylist items (Arraylist class)

SubsetNew searches the entire Arraylist to find and return all items that match a specified criterion. The criterion is supplied by the SelectionCriterion object that is the required SubsetNew parameter. If no item satisfies the criterion, SubsetNew returns an empty Arraylist.

Syntax

%newList = al:SubsetNew( selectionCriterion)

Syntax terms

%newList An Arraylist variable of the same type as the method Arraylist (al) to receive the items that are located by the search. If %newList is not empty, its contents are discarded before it is populated by any items returned from SubsetNew.
al An Arraylist object.
selectionCriterion A SelectionCriterion object, which is a relational expression that is applied to an al item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.

For example, GT(this, -11) is the criterion this > -11, where this is an identity function value that simply returns the item's value. The items that satisfy this expression populate the Arraylist that SubsetNew returns.

The function in the criterion is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the al declaration and that returns a numeric or string value. This is described further in "Specifying a SelectionCriterion's parameters".

Usage notes

Examples

  1. The following request contains two SubsetNew calls, one with a simple selection criterion and one with a compound criterion:

    begin %al is arraylist of float %alnew is arraylist of float %al = list(111, 29, 0, 93, 77, -345) %sel1 is object selectioncriterion for float %sel2 is object selectioncriterion for float %sel1 = GT(this, 0) %sel2 = AND(GE(this, 50), LT(this, 93)) %alnew = %al:SubsetNew(%sel1) Print 'The result of selection1 is:' %alnew:print %alnew = %al:SubsetNew(%sel2) print 'The result of selection2 is:' %alnew:print end

    The result is:

    The result of selection1 is: 1: 111 2: 29 3: 93 4. 77 The result of selection2 is: 1: 93 2: 77

See also

  • FindNextItem without the Start argument is similar to SubsetNew except that it returns just the first matching item it encounters.