net.sf.molae.pipe.basic
Class PipeUtil

java.lang.Object
  net.sf.molae.pipe.basic.PipeUtil

public final class PipeUtil
extends Object

A collection of iterator related utility methods.

Method Summary

static void	assertAssignableFrom(Iterator<?> it, Class<?> cls) Checks that all elements of the specified iterator are assignable to the specified class.
static void	assertIndexes(int fromIndex, int toIndex, int size) Utility method for SubLists.
static <E> Map<E,Integer>	getCardinalityMap(Iterator<E> it) Returns a Map mapping each unique element in the given Iterable to an Integer representing the number of occurrences of that element in the Iterable.
static <E> E	last(Iterator<E> it) Iterates through an iterator to find its last element.
static boolean	removeAll(Iterator<?> it) Removes all elements from the specified iterator.
static int	size(Iterator<?> it) Counts all elments of an iterator.

Methods inherited from class java.lang.Object

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

Method Detail

size

public static int size(Iterator<?> it)

Counts all elments of an iterator.

Parameters:

it - an Iterator object

Returns:

the number of elements of the iterator

last

public static <E> E last(Iterator<E> it)

Iterates through an iterator to find its last element.

Parameters:

it - an Iterator object

Returns:

the last element returned by the specified iterator

Throws:

NoSuchElementException - if iterator is empty

removeAll

public static boolean removeAll(Iterator<?> it)

Removes all elements from the specified iterator.

Parameters:

it - an Iterator object

Returns:

true, if the iterator was not empty before.

Throws:

UnsupportedOperationException - if the specified iterator does not implement the remove method.

assertAssignableFrom

public static void assertAssignableFrom(Iterator<?> it,
                                        Class<?> cls)

Checks that all elements of the specified iterator are assignable to the specified class.

Parameters:

it - an Iterator object

cls - the intended element class of the iterator

Throws:

ClassCastException, - if any element of the specified iterator is not assignable to the specified class.

NullPointerException - if the specified Class parameter is null.

assertIndexes

public static void assertIndexes(int fromIndex,
                                 int toIndex,
                                 int size)

Utility method for SubLists. Checks if

1. fromIndex < 0
2. toIndex > size
3. fromIndex > toIndex

Parameters:

fromIndex - low endpoint (inclusive) of the subList

toIndex - high endpoint (exclusive) of the subList

size - size of the base list

Throws:

IndexOutOfBoundsException - for an illegal endpoint index value (fromIndex < 0 || toIndex > size || fromIndex > toIndex).

getCardinalityMap

public static <E> Map<E,Integer> getCardinalityMap(Iterator<E> it)

Returns a Map mapping each unique element in the given Iterable to an Integer representing the number of occurrences of that element in the Iterable.

Only those elements present in the iterable will appear as keys in the map.

Parameters:

it - the Iterable to get the cardinality map for, must not be null

Returns:

the populated cardinality map

Since:

2.0