Java Reference
In-Depth Information
Table 3-2. ( continued )
Operation
Description
sequenceEqual
Iterates over the two source elements in parallel and compares their corresponding
elements. If all corresponding elements are equal and the collection sizes are equal, then
true is returned. Otherwise, the method returns false .
If a comparator is specified, it is used to compare the elements.
Example: seqA.sequenceEqual(seqB)
defaultIfEmpty
Iterates over and yields all elements of the source collection. If the source collection is
empty, the defaultValue is yielded. If defaultvalue is not specified, a null is yielded.
Example: employees.defaultIfEmpty()
count
Collection.size() is used to obtain the count if there is no predicate function specified
and if the source implements Collection . If the source does not implement Collection ,
then the count operator iterates over the source elements, counting the total number.
If a predicate is specified, the count operator iterates over the source elements and
counts the number of elements for which the predicate function returns true .
Example: employees.count()
sum
Iterates over the source elements, invoking the selector function for each element.
Computes the sum of the returned values. If no selector function is specified, the sum of
the elements in the collection is computed.
Zero is returned for an empty collection. Furthermore, the operator does not include
null values in the result.
Example: [3,5,7,10].sum()
min
Iterates over the source elements, invoking the selector function for each element. Finds
the minimum of the returned values. If no selector function is specified, the minimum of
the elements in the collection is computed. The values to be compared must implement
Comparable .
null is returned for an empty collection.
Example: [3,5,7,10].min() // returns 3
max
Iterates over the source elements, invoking the selector function for each element. Finds
the maximum of the returned values. If no selector function is specified, the maximum of
the elements in the collection is computed. The values to be compared must implement
Comparable .
The max operator returns null for an empty collection.
Example: [3,5,7,10].max() // returns 10
average
Iterates over the source elements, invoking the selector function for each element.
Computes the average of the returned values. If no selector function is specified, the
average of the elements in the collection is calculated.
The average operator returns null for an empty collection.
Example: [3,5,7].average()
( continued )
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