org.deegree.commons.utils
Class CollectionUtils

java.lang.Object
  org.deegree.commons.utils.CollectionUtils

public class CollectionUtils
extends Object

CollectionUtils

Version:

$Revision: 21302 $, $Date: 2009-12-08 09:30:46 +0100 (Di, 08 Dez 2009) $

Author:

Andreas Schmitz, last edited by: $Author: aschmitz $

Nested Class Summary

static interface	CollectionUtils.Mapper<T,U> Mapper gives a name to a simple function.
static interface	CollectionUtils.Reducer<T> Reducer

Field Summary

static CollectionUtils.Reducer<Boolean>	AND
static CollectionUtils.Mapper<String,double[]>	DOUBLE_PRINTER Use like this: System.out.println(map(List object, DOUBLE_PRINTER)) Unfortunately, a generic version for all primitive-arrays is not possible...

Constructor Summary

CollectionUtils()

Method Summary

static <T> CollectionUtils.Mapper<String,T[]>	getArrayPrinter()
static <T> CollectionUtils.Mapper<Boolean,T>	getInstanceofMapper(Class<?> c)
static <T,U> LinkedList<T>	map(Collection<U> col, CollectionUtils.Mapper<T,U> mapper) Wraps a for loop and the creation of a new list.
static <T,U> LinkedList<T>	map(U[] col, CollectionUtils.Mapper<T,U> mapper) Wraps a for loop and the creation of a new list.
static <T> T	reduce(T identity, Collection<T> col, CollectionUtils.Reducer<T> reducer)
static <T> List<T>	removeDuplicates(List<T> list)
static <T,U> Pair<ArrayList<T>,ArrayList<U>>	unzip(Collection<Pair<T,U>> col)

Methods inherited from class java.lang.Object

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

Field Detail

DOUBLE_PRINTER

public static final CollectionUtils.Mapper<String,double[]> DOUBLE_PRINTER

Use like this: System.out.println(map(List object, DOUBLE_PRINTER)) Unfortunately, a generic version for all primitive-arrays is not possible...

AND

public static final CollectionUtils.Reducer<Boolean> AND

Constructor Detail

CollectionUtils

public CollectionUtils()

Method Detail

getArrayPrinter

public static <T> CollectionUtils.Mapper<String,T[]> getArrayPrinter()

Type Parameters:

T -

Returns:

a mapper to output an object array

getInstanceofMapper

public static <T> CollectionUtils.Mapper<Boolean,T> getInstanceofMapper(Class<?> c)

Type Parameters:

T -

Parameters:

c -

Returns:

a list of booleans, true if u instanceof c

removeDuplicates

public static <T> List<T> removeDuplicates(List<T> list)

Type Parameters:

T -

Parameters:

list -

Returns:

removes any duplicates in the list. Keeps the first occurrence of duplicates.

unzip

public static <T,U> Pair<ArrayList<T>,ArrayList<U>> unzip(Collection<Pair<T,U>> col)

Type Parameters:

T -

U -

Parameters:

col -

Returns:

two separate lists

map

public static <T,U> LinkedList<T> map(U[] col,
                                      CollectionUtils.Mapper<T,U> mapper)

Wraps a for loop and the creation of a new list.

Type Parameters:

T -

U -

Parameters:

col -

mapper -

Returns:

a list where the mapper has been applied to each element in the map

map

public static <T,U> LinkedList<T> map(Collection<U> col,
                                      CollectionUtils.Mapper<T,U> mapper)

Wraps a for loop and the creation of a new list.

Type Parameters:

T -

U -

Parameters:

col -

mapper -

Returns:

a list where the mapper has been applied to each element in the map

reduce

public static <T> T reduce(T identity,
                           Collection<T> col,
                           CollectionUtils.Reducer<T> reducer)

Type Parameters:

T -

Parameters:

identity -

col -

reducer -

Returns:

the folded value