org.dstadler.commons.collections

Class MapUtils

java.lang.Object

org.dstadler.commons.collections.MapUtils

public final class MapUtils
extends java.lang.Object

Some helper methods related to Maps, e.g. sorting by value.

Method Summary

Modifier and Type	Method and Description
static <K,V extends java.lang.Comparable<V>> java.util.List<java.util.Map.Entry<K,V>>	sortByValue(java.util.Map<K,V> map) Sorts the provided Map by the value instead of by key like TreeMap does.
static <K extends java.lang.Comparable<K>,V extends java.lang.Comparable<V>> java.util.List<java.util.Map.Entry<K,V>>	sortByValueAndKey(java.util.Map<K,V> map) Sorts the provided Map by the value and then by key instead of by key like TreeMap does.

Methods inherited from class java.lang.Object

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

Method Detail

sortByValue

public static <K,V extends java.lang.Comparable<V>> java.util.List<java.util.Map.Entry<K,V>> sortByValue(java.util.Map<K,V> map)

Sorts the provided Map by the value instead of by key like TreeMap does. The Value-Type needs to implement the Comparable-interface. Note: this will require one Map.Entry for each element in the Map, so for very large Maps this will incur some memory overhead but will not fully duplicate the contents of the map.

Type Parameters:

K - the key-type of the Map that should be sorted

V - the value-type of the Map that should be sorted. Needs to derive from Comparable

Parameters:

map - A map with some elements which should be sorted by Value.

Returns:

Returns a new List of Map.Entry values sorted by value.

sortByValueAndKey

public static <K extends java.lang.Comparable<K>,V extends java.lang.Comparable<V>> java.util.List<java.util.Map.Entry<K,V>> sortByValueAndKey(java.util.Map<K,V> map)

Sorts the provided Map by the value and then by key instead of by key like TreeMap does. The Value-Type and Key-Type need to implement the Comparable-interface. Note: this will require one Map.Entry for each element in the Map, so for very large Maps this will incur some memory overhead but will not fully duplicate the contents of the map.

Type Parameters:

K - the key-type of the Map that should be sorted Needs to derive from Comparable

V - the value-type of the Map that should be sorted. Needs to derive from Comparable

Parameters:

map - A map with some elements which should be sorted by Value first and then by Key.

Returns:

Returns a new List of Map.Entry values sorted by value and key.