Uses of Interface

Packages that use Comparator
Provides classes that are fundamental to the design of the Java programming language.
Provides classes and interfaces for handling text, dates, numbers, and messages in a manner independent of natural languages.
The main API for dates, times, instants, and durations.
Generic API for calendar systems other than the default ISO.
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.
Classes to support functional-style operations on streams of elements, such as map-reduce transformations on collections.
Provides a set of "lightweight" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.
Provides classes and interfaces for dealing with javax.swing.JTable.