hu.akarnokd.reactive4java.util

Class ComparingHashMap<T,U>

java.lang.Object

hu.akarnokd.reactive4java.util.ComparingHashMap<T,U>

Type Parameters:

T - the key type

U - the value type

public class ComparingHashMap<T,U>
extends java.lang.Object

A hash map which uses custom equality comparer on its items.

Note since the new string hashing behavior is hidden under sun.misc, this class implements an older hashing code which might be exploited with well crafted strings.

The implementation is not thread safe.

Note that this is not a complete replacement for java.util.HashMap

Since:

0.97

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	ComparingHashMap.Entry The set entry.

Field Summary

Fields

Modifier and Type	Field and Description
protected Func2<? super T,? super T,java.lang.Boolean>	comparer The comparer function.
protected int	count The current element count.
protected ComparingHashMap.Entry[]	entries The contained entries.
protected double	loadFactor The load factor before the table is resized.
protected int	threshold The load count before the table is resized.

Constructor Summary

Constructors

Constructor and Description
ComparingHashMap() Default constructor with capacity 16, load factor of 0.75 and nullsafe equals() comparer.
ComparingHashMap(Func2<? super T,? super T,java.lang.Boolean> comparer) Constructor with capacity 16, load factor of 0.75 and the given comparer.
ComparingHashMap(int capacity) Constructor with the capacity, load factor of 0.75 and nullsafe equals() comparer.
ComparingHashMap(int capacity, double loadFactor, Func2<? super T,? super T,java.lang.Boolean> comparer) Initializes the set with the given capacity, load factor and comparer.
ComparingHashMap(int capacity, Func2<? super T,? super T,java.lang.Boolean> comparer) Constructor with the given capacity, load factor of 0.75 and the given comparer.

Method Summary

Modifier and Type	Method and Description
protected void	addEntry(int hash, java.lang.Object item, int idx, java.lang.Object value) Adds a new entry to the set, resizing the container as necessary.
U	computeIfAbsent(java.lang.Object key, Func0<? extends U> supplier) Compute and put a new value into the map if the given key is not present.
U	get(java.lang.Object key) Retrieves the value associated with the key or null if not present.
boolean	isEmpty()
U	put(java.lang.Object key, U newValue) Tries to add the given item to this set.
U	putIfAbsent(java.lang.Object key, U newValue) Put a new value into the map if the given key is not present.
protected void	resize(int newSize) Resize the container and remap all its entries.
int	size()
java.lang.Iterable<U>	values()

Methods inherited from class java.lang.Object

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

Field Detail

comparer

protected final Func2<? super T,? super T,java.lang.Boolean> comparer

The comparer function.

entries

protected ComparingHashMap.Entry[] entries

The contained entries.

count

protected int count

The current element count.

loadFactor

protected double loadFactor

The load factor before the table is resized.

threshold

protected int threshold

The load count before the table is resized.

Constructor Detail

ComparingHashMap

public ComparingHashMap()

Default constructor with capacity 16, load factor of 0.75 and nullsafe equals() comparer.

ComparingHashMap

public ComparingHashMap(int capacity)

Constructor with the capacity, load factor of 0.75 and nullsafe equals() comparer.

Parameters:

capacity - the initial capacity.

ComparingHashMap

public ComparingHashMap(@Nonnull
                        Func2<? super T,? super T,java.lang.Boolean> comparer)

Constructor with capacity 16, load factor of 0.75 and the given comparer.

Parameters:

comparer - the comparer function.

ComparingHashMap

public ComparingHashMap(int capacity,
                        @Nonnull
                        Func2<? super T,? super T,java.lang.Boolean> comparer)

Constructor with the given capacity, load factor of 0.75 and the given comparer.

Parameters:

capacity - the initial capacity.

comparer - the comparer function.

ComparingHashMap

public ComparingHashMap(int capacity,
                        double loadFactor,
                        @Nonnull
                        Func2<? super T,? super T,java.lang.Boolean> comparer)

Initializes the set with the given capacity, load factor and comparer.

Parameters:

capacity - the initial capacity, will be rounded up to the next power of 2, minimum 16

loadFactor - the load factor where after the underlying table is resized

comparer - the content comparer

Method Detail

put

public U put(java.lang.Object key,
             U newValue)

Tries to add the given item to this set.

Parameters:

key - the key

newValue - the new value

Returns:

the old value or null if was not present

putIfAbsent

public U putIfAbsent(java.lang.Object key,
                     U newValue)

Put a new value into the map if the given key is not present.

Parameters:

key - the key

newValue - the new value if the key is not present

Returns:

the existing value or the new value if it was added

computeIfAbsent

public U computeIfAbsent(java.lang.Object key,
                         Func0<? extends U> supplier)

Compute and put a new value into the map if the given key is not present.

Parameters:

key - the key

supplier - the new value supplier if the map doesn't contain the key

Returns:

the existing value or the new value if it was added

addEntry

protected void addEntry(int hash,
                        java.lang.Object item,
                        int idx,
                        java.lang.Object value)

Adds a new entry to the set, resizing the container as necessary.

Parameters:

hash - the hash of the item

item - the item

idx - the index

value - the value

resize

protected void resize(int newSize)

Resize the container and remap all its entries.

Parameters:

newSize - the new size

isEmpty

public boolean isEmpty()

Returns:

is this set empty?

size

public int size()

Returns:

the set size.

get

public U get(java.lang.Object key)

Retrieves the value associated with the key or null if not present.

Parameters:

key - the key to check

Returns:

the value or null if not present

values

public java.lang.Iterable<U> values()

Returns:

a sequence of contained elements.