A Queue is a collection designed for processing elements generally in the First In First Out (FIFO) order.

Important properties of Queue interface

1. Methods in Queue interface generally exists in two forms:

   • one throws an exception if the operation fails,

   • the other returns a special value (either null or false, depending on the operation).

TreeMap is a Red-Black tree based NavigableMap implementation.

Important properties of TreeMap

1. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time.

2. Provides guaranteed log(n) time cost for the containsKey, get, put and remove operations.

   • Algorithms are adaptations of those in Cormen, Leiserson, and Rivest's Introduction to Algorithms.

NavigableMap estends SortedMap with navigation methods.

Important properties of NavigableMap

1. Methods lowerEntry, floorEntry, ceilingEntry, and higherEntry return Map.Entry objects associated with keys respectively less than, less than or equal, greater than or equal, and greater than a given key, returning null if there is no such key.

   • Similarly, methods lowerKey, floorKey, ceilingKey, and higherKey return only the associated keys.

SortedMap interface extends Map interface to further provide a total ordering on its keys.

Important Properties of SortedMap

• SortedMap is ordered according to the natural ordering of its keys, or by a Comparator typically provided at sorted map creation time.

• Order is reflected when iterating over the sorted map's collection views returned by the entrySet, keySet and values methods.

• SortedMap is the map analogue of SortedSet.

The unary operator '++expr' is a prefix operator and 'expr++' is a postfix operator.

When used in a assignment or print context (like within a print statement), a prefix operator (e.g. ++a) first increments a and then return the value of a, whereas the postfix operator (e.g. a++) returns the value of a and then increments a.

Expansions for the prefix and postfix shorthand forms

Below expansions will help you understand these operators well.

1. a++ expands to