AbstractPriorityQueue

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java.lang.Object
- net.datastructures.AbstractPriorityQueue<K,V>

All Implemented Interfaces:

PriorityQueue<K,V>

Direct Known Subclasses:

HeapPriorityQueue, SortedPriorityQueue, UnsortedPriorityQueue
```
public abstract class AbstractPriorityQueue<K,V>
extends Object
implements PriorityQueue<K,V>
```
An abstract base class to ease the implementation of the PriorityQueue interface. The base class provides four means of support: 1) It defines a PQEntry class as a concrete implementation of the entry interface 2) It provides an instance variable for a general Comparator and a protected method, compare(a, b), that makes use of the comparator. 3) It provides a boolean checkKey method that verifies that a given key is appropriate for use with the comparator 4) It provides an isEmpty implementation based upon the abstract size() method.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`protected static class`	`AbstractPriorityQueue.PQEntry<K,V>` A concrete implementation of the Entry interface to be used within a PriorityQueue implementation.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`AbstractPriorityQueue()` Creates an empty priority queue based on the natural ordering of its keys.
`protected`	`AbstractPriorityQueue(Comparator<K> c)` Creates an empty priority queue using the given comparator to order keys.

Method Summary

Methods
Modifier and Type	Method and Description
`protected boolean`	`checkKey(K key)` Determines whether a key is valid.
`protected int`	`compare(Entry<K,V> a, Entry<K,V> b)` Method for comparing two entries according to key
`boolean`	`isEmpty()` Tests whether the priority queue is empty.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.datastructures.PriorityQueue
insert, min, removeMin, size

- Constructor Detail
  - AbstractPriorityQueue
```
protected AbstractPriorityQueue(Comparator<K> c)
```
    Creates an empty priority queue using the given comparator to order keys.
    
    Parameters:
    c - comparator defining the order of keys in the priority queue
  - AbstractPriorityQueue
```
protected AbstractPriorityQueue()
```
    Creates an empty priority queue based on the natural ordering of its keys.
- Method Detail
  - compare
```
protected int compare(Entry<K,V> a,
          Entry<K,V> b)
```
    Method for comparing two entries according to key
  - checkKey
```
protected boolean checkKey(K key)
                    throws IllegalArgumentException
```
    Determines whether a key is valid.
    
    Throws:
    
    IllegalArgumentException
  - isEmpty
```
public boolean isEmpty()
```
    Tests whether the priority queue is empty.
    
    Specified by:
    
    isEmpty in interface PriorityQueue<K,V>
    
    Returns:
    true if the priority queue is empty, false otherwise

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