Uses of Class

Packages that use FunctionalInterface
Contains all of the classes for creating user interfaces and for painting graphics and images.
Provides for system input and output through data streams, serialization and the file system.
Provides classes that are fundamental to the design of the Java programming language.
HTTP Client and WebSocket APIs
Defines interfaces and classes for the Java virtual machine to access files, file attributes, and file systems.
Provides the classes and interfaces for the security framework.
Access to date and time using fields and units, and date time adjusters.
Contains the collections framework, some internationalization support classes, a service loader, properties, random number generation, string parsing and scanning classes, base64 encoding and decoding, a bit array, and several miscellaneous utility classes.
Utility classes commonly useful in concurrent programming.
Functional interfaces provide target types for lambda expressions and method references.
Provides the classes and interfaces of the Java 2 platform's core logging facilities.
This package allows applications to store and retrieve user and system preference and configuration data.
Classes to support functional-style operations on streams of elements, such as map-reduce transformations on collections.
Contains the linker for ordinary Java objects.
Contains interfaces and classes needed by language runtimes to implement their own language-specific object models and type conversions.