chtlp / java-kit

Useful Java Tools written/collected by Linpeng Tang

java-kit

Useful Java Tools written/collected by Linpeng Tang

Collections

PriorityMap & HeapMap

A Priority Map is a map that allows you to retrieve/remove the entry with the smallest key with high efficiency. In this library, Priority Map is impelemented by HeapMap.

You can use it to implement a Priority Queue that allows you to update the priority value of the keys (just update the value of that key).

For example,

PriorityMap<String, Integer> map = new HeapMap<String, Integer>();
map.put("A", 1);
map.put("B", 2);

creates a Priority Map with 2 entries. map.peakKey() will now return "A". Now go ahead and change the values:

map.put("A", 3);

Now map.peakKey() will return "B".

Many caching policies can be implemented with Priority Map.