Package com.helger.commons.collection

Class IteratorHelper

java.lang.Object

com.helger.commons.collection.IteratorHelper

public final class IteratorHelper
extends Object

Helper class containing several Iterator, Iterable, Enumeration etc. helper methods.

Author:

Philip Helger

Method Summary

Modifier and Type	Method	Description
static <ELEMENTTYPE> Iterator<ELEMENTTYPE>	getCombinedIterator(Iterator<? extends ELEMENTTYPE> aIter1, Iterator<? extends ELEMENTTYPE> aIter2)	Get a merged iterator of both iterators.
static <ELEMENTTYPE> Enumeration<ELEMENTTYPE>	getEnumeration(ELEMENTTYPE... aArray)	Get an Enumeration object based on the passed array.
static <ELEMENTTYPE> Enumeration<ELEMENTTYPE>	getEnumeration(Iterable<ELEMENTTYPE> aCont)	Get an Enumeration object based on a Collection object.
static <ELEMENTTYPE> Enumeration<ELEMENTTYPE>	getEnumeration(Iterator<ELEMENTTYPE> aIter)	Get an Enumeration object based on an Iterator object.
static <KEYTYPE,VALUETYPE> Enumeration<Map.Entry<KEYTYPE,VALUETYPE>>	getEnumeration(Map<KEYTYPE,VALUETYPE> aMap)	Get an Enumeration object based on a Map object.
static <ELEMENTTYPE> Iterator<ELEMENTTYPE>	getIterator(ELEMENTTYPE... aArray)
static <ELEMENTTYPE> Iterator<ELEMENTTYPE>	getIterator(Iterable<ELEMENTTYPE> aCont)
static <ELEMENTTYPE> IIterableIterator<ELEMENTTYPE>	getIterator(Enumeration<? extends ELEMENTTYPE> aEnum)
static <ELEMENTTYPE> Iterator<ELEMENTTYPE>	getIterator(Iterator<ELEMENTTYPE> aIter)
static <ELEMENTTYPE> Iterator<ELEMENTTYPE>	getReverseIterator(List<? extends ELEMENTTYPE> aCont)
static int	getSize(IIterableIterator<?> aIterator)	Retrieve the size of the passed Iterable.
static int	getSize(Enumeration<?> aEnumeration)	Retrieve the size of the passed Enumeration.
static int	getSize(Iterator<?> aIterator)	Retrieve the size of the passed Iterator.
static boolean	isEmpty(IIterableIterator<?> aIter)
static boolean	isEmpty(Enumeration<?> aEnum)
static boolean	isEmpty(Iterator<?> aIter)
static boolean	isNotEmpty(IIterableIterator<?> aIter)
static boolean	isNotEmpty(Enumeration<?> aEnum)
static boolean	isNotEmpty(Iterator<?> aIter)

Methods inherited from class java.lang.Object

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

Method Detail

isEmpty

public static boolean isEmpty(@Nullable
                              Iterator<?> aIter)

isEmpty

public static boolean isEmpty(@Nullable
                              IIterableIterator<?> aIter)

isEmpty

public static boolean isEmpty(@Nullable
                              Enumeration<?> aEnum)

isNotEmpty

public static boolean isNotEmpty(@Nullable
                                 Iterator<?> aIter)

isNotEmpty

public static boolean isNotEmpty(@Nullable
                                 IIterableIterator<?> aIter)

isNotEmpty

public static boolean isNotEmpty(@Nullable
                                 Enumeration<?> aEnum)

getSize

@Nonnegative
public static int getSize(@Nullable
                          IIterableIterator<?> aIterator)

Retrieve the size of the passed Iterable.

Parameters:

aIterator - Iterable iterator to check. May be null.

Returns:

The number objects or 0 if the passed parameter is null.

getSize

@Nonnegative
public static int getSize(@Nullable
                          Iterator<?> aIterator)

Retrieve the size of the passed Iterator.

Parameters:

aIterator - Iterator to check. May be null.

Returns:

The number objects or 0 if the passed parameter is null.

getSize

@Nonnegative
public static int getSize(@Nullable
                          Enumeration<?> aEnumeration)

Retrieve the size of the passed Enumeration.

Parameters:

aEnumeration - Enumeration to check. May be null.

Returns:

The number objects or 0 if the passed parameter is null.

getIterator

@Nonnull
public static <ELEMENTTYPE> IIterableIterator<ELEMENTTYPE> getIterator(@Nullable
                                                                       Enumeration<? extends ELEMENTTYPE> aEnum)

getIterator

@Nonnull
public static <ELEMENTTYPE> Iterator<ELEMENTTYPE> getIterator(@Nullable
                                                              Iterable<ELEMENTTYPE> aCont)

getIterator

@Nonnull
public static <ELEMENTTYPE> Iterator<ELEMENTTYPE> getIterator(@Nullable
                                                              Iterator<ELEMENTTYPE> aIter)

getIterator

@Nonnull
@SafeVarargs
public static <ELEMENTTYPE> Iterator<ELEMENTTYPE> getIterator(@Nullable
                                                              ELEMENTTYPE... aArray)

getReverseIterator

@Nonnull
public static <ELEMENTTYPE> Iterator<ELEMENTTYPE> getReverseIterator(@Nullable
                                                                     List<? extends ELEMENTTYPE> aCont)

getCombinedIterator

@Nonnull
public static <ELEMENTTYPE> Iterator<ELEMENTTYPE> getCombinedIterator(@Nullable
                                                                      Iterator<? extends ELEMENTTYPE> aIter1,
                                                                      @Nullable
                                                                      Iterator<? extends ELEMENTTYPE> aIter2)

Get a merged iterator of both iterators. The first iterator is iterated first, the second one afterwards.

Type Parameters:

ELEMENTTYPE - The type of elements to be enumerated.

Parameters:

aIter1 - First iterator. May be null.

aIter2 - Second iterator. May be null.

Returns:

The merged iterator. Never null.

getEnumeration

@Nonnull
public static <ELEMENTTYPE> Enumeration<ELEMENTTYPE> getEnumeration(@Nullable
                                                                    Iterable<ELEMENTTYPE> aCont)

Get an Enumeration object based on a Collection object.

Type Parameters:

ELEMENTTYPE - the type of the elements in the container

Parameters:

aCont - The container to enumerate.

Returns:

an Enumeration object

getEnumeration

@Nonnull
@SafeVarargs
public static <ELEMENTTYPE> Enumeration<ELEMENTTYPE> getEnumeration(@Nullable
                                                                    ELEMENTTYPE... aArray)

Get an Enumeration object based on the passed array.

Type Parameters:

ELEMENTTYPE - the type of the elements in the container

Parameters:

aArray - The array to enumerate.

Returns:

an Enumeration object

getEnumeration

@Nonnull
public static <ELEMENTTYPE> Enumeration<ELEMENTTYPE> getEnumeration(@Nullable
                                                                    Iterator<ELEMENTTYPE> aIter)

Get an Enumeration object based on an Iterator object.

Type Parameters:

ELEMENTTYPE - the type of the elements in the container

Parameters:

aIter - iterator object to use

Returns:

an Enumeration object

getEnumeration

@Nonnull
public static <KEYTYPE,VALUETYPE> Enumeration<Map.Entry<KEYTYPE,VALUETYPE>> getEnumeration(@Nullable
                                                                                                       Map<KEYTYPE,VALUETYPE> aMap)

Get an Enumeration object based on a Map object.

Type Parameters:

KEYTYPE - map key type

VALUETYPE - map value type

Parameters:

aMap - map object to use

Returns:

an Enumeration object