| 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 | Description | 
|---|---|---|
class  | 
PriorityQueue<E>
An unbounded priority queue based on a priority heap. 
 | 
| Modifier and Type | Class | 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
  
Delayed elements, 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  
TransferQueue based on linked nodes. | 
|
class  | 
PriorityBlockingQueue<E>
An unbounded blocking queue that uses
 the same ordering rules as class  
PriorityQueue and 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. 
 | 
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