| Package | Description | 
|---|---|
| java.util | Contains the collections framework, legacy collection classes, event model,
date and time facilities, internationalization, and miscellaneous utility
classes (a string tokenizer, a random-number generator, and a bit array). | 
| java.util.concurrent | Utility classes commonly useful in concurrent programming. | 
| Modifier and Type | Class and Description | 
|---|---|
| class  | PriorityQueue<E>An unbounded priority queue based on a priority heap. | 
| Modifier and Type | Class and Description | 
|---|---|
| class  | ArrayBlockingQueue<E>A bounded blocking queue backed by an
 array. | 
| class  | ConcurrentLinkedQueue<E>An unbounded thread-safe queue based on linked nodes. | 
| class  | DelayQueue<E extends Delayed>An unbounded blocking queue of
  Delayedelements, in which an element can only be taken
 when its delay has expired. | 
| class  | LinkedBlockingDeque<E>An optionally-bounded blocking deque based on
 linked nodes. | 
| class  | LinkedBlockingQueue<E>An optionally-bounded blocking queue based on
 linked nodes. | 
| class  | LinkedTransferQueue<E>An unbounded  TransferQueuebased on linked nodes. | 
| class  | PriorityBlockingQueue<E>An unbounded blocking queue that uses
 the same ordering rules as class  PriorityQueueand supplies
 blocking retrieval operations. | 
| class  | SynchronousQueue<E>A blocking queue in which each insert
 operation must wait for a corresponding remove operation by another
 thread, and vice versa. | 
 Submit a bug or feature 
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
 Copyright © 1993, 2025, Oracle and/or its affiliates.  All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.