Package net.sf.colossus.util
Class CollectionHelper
- java.lang.Object
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- net.sf.colossus.util.CollectionHelper
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public class CollectionHelper extends java.lang.Object
A collection of static methods to help with using java.util.Collection derivates. This is an addition toCollections
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Constructor Summary
Constructors Constructor Description CollectionHelper()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static <T> void
copySelective(java.util.Collection<? extends T> source, java.util.Collection<? super T> target, Predicate<T> filter)
Copies all elements that match a predicate.static <T> java.util.List<T>
selectAsList(java.util.Collection<? extends T> source, Predicate<T> filter)
Retrieves all elements from a collection that match a predicate.static <T> T
selectFirst(java.util.Collection<? extends T> source, Predicate<T> filter)
Retrieves the first element from a collection that matches a predicate.
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Method Detail
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copySelective
public static <T> void copySelective(java.util.Collection<? extends T> source, java.util.Collection<? super T> target, Predicate<T> filter)
Copies all elements that match a predicate. Every element of the first collection for which the predicate holds (i.e. returns true) is added to the second collection.
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selectAsList
public static <T> java.util.List<T> selectAsList(java.util.Collection<? extends T> source, Predicate<T> filter)
Retrieves all elements from a collection that match a predicate. The result will be all elements of the source collection for which the predicate is true, retrieved in normal iteration order.- Type Parameters:
T
- The type of elements we are interested in.- Parameters:
source
- A collection containing elements we are interested in. Not null. Can be empty.filter
- The predicate determining if an element is to be retrieved. Not null.- Returns:
- A list containing all matching elements in iteration order. Never null. Can be empty.
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selectFirst
public static <T> T selectFirst(java.util.Collection<? extends T> source, Predicate<T> filter)
Retrieves the first element from a collection that matches a predicate.- Type Parameters:
T
- The type of elements we are interested in.- Parameters:
source
- A collection containing elements we are interested in. Not null. Can be empty.filter
- The predicate determining if an element is to be retrieved. Not null.- Returns:
- The first matching element or null if no element matches.
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