Package  Description 

java.lang 
Provides classes that are fundamental to the design of the Java
programming language.

java.nio.file 
Defines interfaces and classes for the Java virtual machine to access files,
file attributes, and file systems.

java.security 
Provides the classes and interfaces for the security framework.

java.time.temporal 
Access to date and time using fields and units, and date time adjusters.

java.util 
Contains the collections framework, legacy collection classes, event model,
date and time facilities, internationalization, and miscellaneous utility
classes (a string tokenizer, a randomnumber generator, and a bit array).

java.util.concurrent 
Utility classes commonly useful in concurrent programming.

java.util.concurrent.atomic 
A small toolkit of classes that support lockfree threadsafe
programming on single variables.

java.util.function 
Functional interfaces provide target types for lambda expressions
and method references.

java.util.logging 
Provides the classes and interfaces of
the Java^{TM} 2
platform's core logging facilities.

java.util.regex 
Classes for matching character sequences against patterns specified by regular
expressions.

java.util.stream 
Classes to support functionalstyle operations on streams of elements, such
as mapreduce transformations on collections.

Class and Description 

Consumer
Represents an operation that accepts a single input argument and returns no
result.

Supplier
Represents a supplier of results.

Class and Description 

BiPredicate
Represents a predicate (booleanvalued function) of two arguments.

Class and Description 

BiConsumer
Represents an operation that accepts two input arguments and returns no
result.

BiFunction
Represents a function that accepts two arguments and produces a result.

Function
Represents a function that accepts one argument and produces a result.

Class and Description 

UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

Class and Description 

BiConsumer
Represents an operation that accepts two input arguments and returns no
result.

BiFunction
Represents a function that accepts two arguments and produces a result.

BinaryOperator
Represents an operation upon two operands of the same type, producing a result
of the same type as the operands.

Consumer
Represents an operation that accepts a single input argument and returns no
result.

DoubleBinaryOperator
Represents an operation upon two
double valued operands and producing a
double valued result. 
DoubleConsumer
Represents an operation that accepts a single
double valued argument and
returns no result. 
DoubleSupplier
Represents a supplier of
double valued results. 
Function
Represents a function that accepts one argument and produces a result.

IntBinaryOperator
Represents an operation upon two
int valued operands and producing an
int valued result. 
IntConsumer
Represents an operation that accepts a single
int valued argument and
returns no result. 
IntFunction
Represents a function that accepts an intvalued argument and produces a
result.

IntSupplier
Represents a supplier of
int valued results. 
IntToDoubleFunction
Represents a function that accepts an intvalued argument and produces a
doublevalued result.

IntToLongFunction
Represents a function that accepts an intvalued argument and produces a
longvalued result.

IntUnaryOperator
Represents an operation on a single
int valued operand that produces
an int valued result. 
LongBinaryOperator
Represents an operation upon two
long valued operands and producing a
long valued result. 
LongConsumer
Represents an operation that accepts a single
long valued argument and
returns no result. 
LongSupplier
Represents a supplier of
long valued results. 
Predicate
Represents a predicate (booleanvalued function) of one argument.

Supplier
Represents a supplier of results.

ToDoubleFunction
Represents a function that produces a doublevalued result.

ToIntFunction
Represents a function that produces an intvalued result.

ToLongFunction
Represents a function that produces a longvalued result.

UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

Class and Description 

BiConsumer
Represents an operation that accepts two input arguments and returns no
result.

BiFunction
Represents a function that accepts two arguments and produces a result.

Consumer
Represents an operation that accepts a single input argument and returns no
result.

DoubleBinaryOperator
Represents an operation upon two
double valued operands and producing a
double valued result. 
Function
Represents a function that accepts one argument and produces a result.

IntBinaryOperator
Represents an operation upon two
int valued operands and producing an
int valued result. 
LongBinaryOperator
Represents an operation upon two
long valued operands and producing a
long valued result. 
Predicate
Represents a predicate (booleanvalued function) of one argument.

Supplier
Represents a supplier of results.

ToDoubleBiFunction
Represents a function that accepts two arguments and produces a doublevalued
result.

ToDoubleFunction
Represents a function that produces a doublevalued result.

ToIntBiFunction
Represents a function that accepts two arguments and produces an intvalued
result.

ToIntFunction
Represents a function that produces an intvalued result.

ToLongBiFunction
Represents a function that accepts two arguments and produces a longvalued
result.

ToLongFunction
Represents a function that produces a longvalued result.

UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

Class and Description 

BinaryOperator
Represents an operation upon two operands of the same type, producing a result
of the same type as the operands.

DoubleBinaryOperator
Represents an operation upon two
double valued operands and producing a
double valued result. 
IntBinaryOperator
Represents an operation upon two
int valued operands and producing an
int valued result. 
IntUnaryOperator
Represents an operation on a single
int valued operand that produces
an int valued result. 
LongBinaryOperator
Represents an operation upon two
long valued operands and producing a
long valued result. 
LongUnaryOperator
Represents an operation on a single
long valued operand that produces
a long valued result. 
UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

Class and Description 

BiConsumer
Represents an operation that accepts two input arguments and returns no
result.

BiFunction
Represents a function that accepts two arguments and produces a result.

BinaryOperator
Represents an operation upon two operands of the same type, producing a result
of the same type as the operands.

BiPredicate
Represents a predicate (booleanvalued function) of two arguments.

Consumer
Represents an operation that accepts a single input argument and returns no
result.

DoubleConsumer
Represents an operation that accepts a single
double valued argument and
returns no result. 
DoublePredicate
Represents a predicate (booleanvalued function) of one
double valued
argument. 
DoubleUnaryOperator
Represents an operation on a single
double valued operand that produces
a double valued result. 
Function
Represents a function that accepts one argument and produces a result.

IntConsumer
Represents an operation that accepts a single
int valued argument and
returns no result. 
IntPredicate
Represents a predicate (booleanvalued function) of one
int valued
argument. 
IntUnaryOperator
Represents an operation on a single
int valued operand that produces
an int valued result. 
LongConsumer
Represents an operation that accepts a single
long valued argument and
returns no result. 
LongPredicate
Represents a predicate (booleanvalued function) of one
long valued
argument. 
LongUnaryOperator
Represents an operation on a single
long valued operand that produces
a long valued result. 
Predicate
Represents a predicate (booleanvalued function) of one argument.

UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

Class and Description 

Supplier
Represents a supplier of results.

Class and Description 

Predicate
Represents a predicate (booleanvalued function) of one argument.

Class and Description 

BiConsumer
Represents an operation that accepts two input arguments and returns no
result.

BiFunction
Represents a function that accepts two arguments and produces a result.

BinaryOperator
Represents an operation upon two operands of the same type, producing a result
of the same type as the operands.

Consumer
Represents an operation that accepts a single input argument and returns no
result.

DoubleBinaryOperator
Represents an operation upon two
double valued operands and producing a
double valued result. 
DoubleConsumer
Represents an operation that accepts a single
double valued argument and
returns no result. 
DoubleFunction
Represents a function that accepts a doublevalued argument and produces a
result.

DoublePredicate
Represents a predicate (booleanvalued function) of one
double valued
argument. 
DoubleSupplier
Represents a supplier of
double valued results. 
DoubleToIntFunction
Represents a function that accepts a doublevalued argument and produces an
intvalued result.

DoubleToLongFunction
Represents a function that accepts a doublevalued argument and produces a
longvalued result.

DoubleUnaryOperator
Represents an operation on a single
double valued operand that produces
a double valued result. 
Function
Represents a function that accepts one argument and produces a result.

IntBinaryOperator
Represents an operation upon two
int valued operands and producing an
int valued result. 
IntConsumer
Represents an operation that accepts a single
int valued argument and
returns no result. 
IntFunction
Represents a function that accepts an intvalued argument and produces a
result.

IntPredicate
Represents a predicate (booleanvalued function) of one
int valued
argument. 
IntSupplier
Represents a supplier of
int valued results. 
IntToDoubleFunction
Represents a function that accepts an intvalued argument and produces a
doublevalued result.

IntToLongFunction
Represents a function that accepts an intvalued argument and produces a
longvalued result.

IntUnaryOperator
Represents an operation on a single
int valued operand that produces
an int valued result. 
LongBinaryOperator
Represents an operation upon two
long valued operands and producing a
long valued result. 
LongConsumer
Represents an operation that accepts a single
long valued argument and
returns no result. 
LongFunction
Represents a function that accepts a longvalued argument and produces a
result.

LongPredicate
Represents a predicate (booleanvalued function) of one
long valued
argument. 
LongSupplier
Represents a supplier of
long valued results. 
LongToDoubleFunction
Represents a function that accepts a longvalued argument and produces a
doublevalued result.

LongToIntFunction
Represents a function that accepts a longvalued argument and produces an
intvalued result.

LongUnaryOperator
Represents an operation on a single
long valued operand that produces
a long valued result. 
ObjDoubleConsumer
Represents an operation that accepts an objectvalued and a
double valued argument, and returns no result. 
ObjIntConsumer
Represents an operation that accepts an objectvalued and a
int valued argument, and returns no result. 
ObjLongConsumer
Represents an operation that accepts an objectvalued and a
long valued argument, and returns no result. 
Predicate
Represents a predicate (booleanvalued function) of one argument.

Supplier
Represents a supplier of results.

ToDoubleFunction
Represents a function that produces a doublevalued result.

ToIntFunction
Represents a function that produces an intvalued result.

ToLongFunction
Represents a function that produces a longvalued result.

UnaryOperator
Represents an operation on a single operand that produces a result of the
same type as its operand.

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For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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