FindNextItem (Arraylist function)

<section begin=dpl_desc/>Find matching Arraylist item<section end=dpl_desc/>

FindNextItem is a member of the Arraylist class.

This function searches “forward” in the Arraylist to find and return the next item that matches a specified criterion. The criterion is supplied by the SelectionCriterion object that is a required FindNextItem parameter. If no item satisfies the criterion, the request is cancelled and an ItemNotFound exception (?? refid=itemnfe.) is thrown.

FindNextItem is available in Sirius Mods version 7.6 and later.

Syntax

  %item = %arrayl:FindNextItem(criterion [, Start=itemnum])

Syntax Terms

%item

A variable of the type of the items in the Arraylist to contain the item that is located by the search.

%arrayl

An Arraylist object.

criterion

A SelectionCriterion object, which is a relational expression that is applied to an %arrayl 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 that simply returns the item's value. The first item tested by FindNextItem that satisfies this expression is the method's return value. 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 %arrayl declaration and that returns a numeric or string value. This is described further in "Specifying a SelectionCriterion's parameters".

Start= itemnum

The number of the item after which to begin the search. If the itemnum value of Start is 2, item 3 is the first item considered. The value of Start may be 0 through the number of items in the collection. For a collection of three items, itemnum may be 0, 1, 2, or 3. This is an optional argument, and it defaults to 0. If you specify a value, the parameter name Start is required.

Usage Notes

• If the value of Start is greater than the number of items in the Arraylist, the request is cancelled. If the value of Start is equal to the number of items, the request is cancelled, but an ItemNotFound exception is thrown.
• FindPreviousItem is identical to FindNextItem except that it searches backward in the Arraylist.

Examples

• The following request contains three FindNextItem calls, two with a simple selection criterion and one with a compound criterion. The second FindNextItem call fails, but a Try clause catches the exception and issues a third FindNextItem call:

      Begin
      %al 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))
  
      printtext {~} is: {%al:findNextItem(%sel1, start=2)}
  
      try printtext {~} is: {%al:findNextItem(%sel1, start=4)}
        catch ItemNotFound
        Print '***Does not work***'
        try printtext {~} is: {%al:findNextItem(%sel2)}
           catch ItemNotFound
           Print '***Does not work***'
        end try
      end try
  
      End
  

  The result is:

      %al:findNextItem(%sel1, start=2) is: 93
      %al:findNextItem(%sel1, start=5) is: ***Does not work***
      %al:findNextItem(%sel2) is: 77