org.jutil.java.collections
Class Counter

java.lang.Object
  |
  +--org.jutil.java.collections.IntegerAccumulator
        |
        +--org.jutil.java.collections.Counter

All Implemented Interfaces:

CollectionOperator

public abstract class Counter

extends IntegerAccumulator

An IntegerAccumulator that counts the number of items in a collection that satisfies some criterion.

A convenience accumulator of collections that checks elements of a collection satisfy the criterion defined in public boolean criterion(Object element).

As with the accumulator, this class can best be used as an anonymous inner class, as shown below.

 int number = new Counter() {
                public boolean criterion(Object element) {
                  // criterion code
                }
              }.in(collection);
 

Field Summary
static java.lang.String	CVS_REVISION

 

Constructor Summary

Counter()

 

Method Summary
int	accumulate(java.lang.Object element, int acc)
abstract  boolean	criterion(java.lang.Object element)           The criterion used to determine whether or not an element has to be counted.
int	initialAccumulator()

 

Methods inherited from class org.jutil.java.collections.IntegerAccumulator

in

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Methods inherited from interface org.jutil.java.collections.CollectionOperator

isValidElement

 

Field Detail

CVS_REVISION

public static final java.lang.String CVS_REVISION

Counter

public Counter()

initialAccumulator

public int initialAccumulator()

Specifications:

     also

public behavior
ensures \result == 0;

Specifications inherited from overridden method in class IntegerAccumulator:
      --- None ---

accumulate

public int accumulate(java.lang.Object element,
                      int acc)

Specifications:

     also

public behavior
ensures criterion(element) == false ==> \result == acc;
ensures criterion(element) == true ==> \result == acc+1;

Specifications inherited from overridden method in class IntegerAccumulator:

requires element != null;

criterion

public abstract boolean criterion(java.lang.Object element)

The criterion used to determine whether or not an element has to be counted.

Specifications:

ensures ( \forall Object o1; ; ( \forall Object o2; o1.equals(o2); criterion(o1) == criterion(o2)));