Queue

What kind of problems are commonly solved via queues:

• typicall problems that work based on the "first come first serve" statement
• lineup problems, like a human string aligned to buy tickets to a concert
• Breadth First Search (BFS) graph traversal
• Tracking most recent added elements

Java Queue Implementations

java.util.Queue ("single end"): add things to one end and take them from the other (FIFO)
java.util.Deque ("double ended queue"): add things to either end, and take them from either end
java.util.Deque is a subiterface of java.utilQueue

• java.util.ArrayDeque, not thread-safe, example
• java.util.concurrent.ArrayBlockingQueue, thread-safe, example
• java.util.concurrent.ConcurrentLinkedDeque and java.util.concurrent.ConcurrentLinkedQueue, thread-safe, example
• java.util.LinkedList, not thread-safe and not efficient, example