Package java.util.function

Functional interfaces provide typing for lambda expressions.

See: Description

Interface Summary

Interface	Description
BiBlock<L,R>	An operation upon input objects.
BiFunction<T,U,R>	Apply a function to the input objects yielding an appropriate result object.
BinaryOperator<T>	An operation upon two operands yielding a result.
BiPredicate<L,R>	Determines if the input object matches some criteria.
Block<T>	An operation upon an input object.
DoubleBinaryOperator	An operation on two double operands yielding a double result.
DoubleBlock	An operation upon a double input value.
DoubleFunction<T>	Apply a function to the input object yielding an appropriate double value; this is the double-bearing specialization for Function.
DoublePredicate	Determines if the long input value matches some criteria.
DoubleSupplier	A supplier of double values.
DoubleUnaryOperator	An operation on a single double operand yielding a double result.
FlatMapper<T,R>	Map an element to zero or more results and add all results to a sink.
Function<T,R>	Apply a function to the input object yielding an appropriate result object.
IntBinaryOperator	An operation on two int operands yielding an int result.
IntBlock	An operation upon an int input value.
IntFunction<T>	Apply a function to the input object yielding an appropriate int value; this is the int-bearing specialization for Function.
IntPredicate	Determines if the int input value matches some criteria.
IntSupplier	A supplier of int values.
IntUnaryOperator	An operation on a single int operand yielding an int result.
LongBinaryOperator	An operation on two long operands yielding a long result.
LongBlock	An operation upon a long input value.
LongFunction<T>	Apply a function to the input object yielding an appropriate long value; this is the long-bearing specialization for Function.
LongPredicate	Determines if the long input value matches some criteria.
LongSupplier	A supplier of long values.
LongUnaryOperator	An operation on a single long operand yielding a long result.
Predicate<T>	Determines if the input object matches some criteria.
Supplier<T>	A supplier of objects.
UnaryOperator<T>	An operation upon a single operand yielding a result.

Class Summary

Class	Description
Functions	Static utility methods pertaining to Mapper instances.
Predicates	Static utility methods pertaining to Predicate instances.

Package java.util.function Description

Functional interfaces provide typing for lambda expressions. Each functional interface provides a single abstract method to which the lambda expression's parameter and return types are matched.

The interfaces in this package are all functional interfaces used with the collections and streams frameworks. The operation identified by each interface is generally applied to a collection or stream of objects.

All functional interface implementations are expected to ensure that:

• When used for aggregate operations upon many elements it should not be assumed that the operation will be called upon elements in any specific order.
• null values are accepted and returned by these functional interfaces according to the constraints of the specification in which the functional interfaces are used. The functional interfaces themselves do not constrain or mandate use of null values. Most usages of the functional interfaces will define the role, if any, of null for that context.