ObjectIntMap (libgdx API)

java.lang.Object
- com.badlogic.gdx.utils.ObjectIntMap<K>

All Implemented Interfaces:

java.lang.Iterable<ObjectIntMap.Entry<K>>
```
public class ObjectIntMap<K>
extends java.lang.Object
implements java.lang.Iterable<ObjectIntMap.Entry<K>>
```
An unordered map where the keys are objects and the values are unboxed ints. Null keys are not allowed. No allocation is done except when growing the table size.
This class performs fast contains and remove (typically O(1), worst case O(n) but that is rare in practice). Add may be slightly slower, depending on hash collisions. Hashcodes are rehashed to reduce collisions and the need to resize. Load factors greater than 0.91 greatly increase the chances to resize to the next higher POT size.
Unordered sets and maps are not designed to provide especially fast iteration. Iteration is faster with OrderedSet and OrderedMap.
This implementation uses linear probing with the backward shift algorithm for removal. Hashcodes are rehashed using Fibonacci hashing, instead of the more common power-of-two mask, to better distribute poor hashCodes (see Malte Skarupke's blog post). Linear probing continues to work even when all hashCodes collide, just more slowly.

Author:

Nathan Sweet, Tommy Ettinger

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`ObjectIntMap.Entries<K>`
`static class`	`ObjectIntMap.Entry<K>`
`static class`	`ObjectIntMap.Keys<K>`
`static class`	`ObjectIntMap.Values`

Field Summary

Fields
Modifier and Type	Field and Description
`protected int`	`mask` A bitmask used to confine hashcodes to the size of the table.
`protected int`	`shift` Used by `place(Object)` to bit shift the upper bits of a `long` into a usable range (>= 0 and <= `mask`).
`int`	`size`

Constructor Summary

Constructors
Constructor and Description
`ObjectIntMap()` Creates a new map with an initial capacity of 51 and a load factor of 0.8.
`ObjectIntMap(int initialCapacity)` Creates a new map with a load factor of 0.8.
`ObjectIntMap(int initialCapacity, float loadFactor)` Creates a new map with the specified initial capacity and load factor.
`ObjectIntMap(ObjectIntMap<? extends K> map)` Creates a new map identical to the specified map.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()`
`void`	`clear(int maximumCapacity)` Clears the map and reduces the size of the backing arrays to be the specified capacity / loadFactor, if they are larger.
`boolean`	`containsKey(K key)`
`boolean`	`containsValue(int value)` Returns true if the specified value is in the map.
`void`	`ensureCapacity(int additionalCapacity)` Increases the size of the backing array to accommodate the specified number of additional items / loadFactor.
`ObjectIntMap.Entries<K>`	`entries()` Returns an iterator for the entries in the map.
`boolean`	`equals(java.lang.Object obj)`
`K`	`findKey(int value)` Returns the key for the specified value, or null if it is not in the map.
`int`	`get(K key, int defaultValue)` Returns the value for the specified key, or the default value if the key is not in the map.
`int`	`getAndIncrement(K key, int defaultValue, int increment)` Returns the key's current value and increments the stored value.
`int`	`hashCode()`
`boolean`	`isEmpty()` Returns true if the map is empty.
`ObjectIntMap.Entries<K>`	`iterator()`
`ObjectIntMap.Keys<K>`	`keys()` Returns an iterator for the keys in the map.
`boolean`	`notEmpty()` Returns true if the map has one or more items.
`protected int`	`place(K item)` Returns an index >= 0 and <= `mask` for the specified `item`.
`void`	`put(K key, int value)`
`int`	`put(K key, int value, int defaultValue)` Returns the old value associated with the specified key, or the specified default value.
`void`	`putAll(ObjectIntMap<? extends K> map)`
`int`	`remove(K key, int defaultValue)` Returns the value for the removed key, or the default value if the key is not in the map.
`void`	`shrink(int maximumCapacity)` Reduces the size of the backing arrays to be the specified capacity / loadFactor, or less.
`java.lang.String`	`toString()`
`java.lang.String`	`toString(java.lang.String separator)`
`ObjectIntMap.Values`	`values()` Returns an iterator for the values in the map.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Field Detail
  - size
```
public int size
```
  - shift
```
protected int shift
```
    Used by place(Object) to bit shift the upper bits of a long into a usable range (>= 0 and <= mask). The shift can be negative, which is convenient to match the number of bits in mask: if mask is a 7-bit number, a shift of -7 shifts the upper 7 bits into the lowest 7 positions. This class sets the shift > 32 and < 64, which if used with an int will still move the upper bits of an int to the lower bits due to Java's implicit modulus on shifts.
    mask can also be used to mask the low bits of a number, which may be faster for some hashcodes, if place(Object) is overridden.
  - mask
```
protected int mask
```
    A bitmask used to confine hashcodes to the size of the table. Must be all 1 bits in its low positions, ie a power of two minus 1. If place(Object) is overriden, this can be used instead of shift to isolate usable bits of a hash.
- Constructor Detail
  - ObjectIntMap
```
public ObjectIntMap()
```
    Creates a new map with an initial capacity of 51 and a load factor of 0.8.
  - ObjectIntMap
```
public ObjectIntMap(int initialCapacity)
```
    Creates a new map with a load factor of 0.8.
    
    Parameters:
    
    initialCapacity - If not a power of two, it is increased to the next nearest power of two.
  - ObjectIntMap
```
public ObjectIntMap(int initialCapacity,
                    float loadFactor)
```
    Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity items before growing the backing table.
    
    Parameters:
    
    initialCapacity - If not a power of two, it is increased to the next nearest power of two.
  - ObjectIntMap
```
public ObjectIntMap(ObjectIntMap<? extends K> map)
```
    Creates a new map identical to the specified map.
- Method Detail
  - place
```
protected int place(K item)
```
    Returns an index >= 0 and <= mask for the specified item.
    The default implementation uses Fibonacci hashing on the item's Object.hashCode(): the hashcode is multiplied by a long constant (2 to the 64th, divided by the golden ratio) then the uppermost bits are shifted into the lowest positions to obtain an index in the desired range. Multiplication by a long may be slower than int (eg on GWT) but greatly improves rehashing, allowing even very poor hashcodes, such as those that only differ in their upper bits, to be used without high collision rates. Fibonacci hashing has increased collision rates when all or most hashcodes are multiples of larger Fibonacci numbers (see Malte Skarupke's blog post).
    This method can be overriden to customizing hashing. This may be useful eg in the unlikely event that most hashcodes are Fibonacci numbers, if keys provide poor or incorrect hashcodes, or to simplify hashing if keys provide high quality hashcodes and don't need Fibonacci hashing: return item.hashCode() & mask;
  - put
```
public void put(K key,
                int value)
```
  - put
```
public int put(K key,
               int value,
               int defaultValue)
```
    Returns the old value associated with the specified key, or the specified default value.
  - putAll
```
public void putAll(ObjectIntMap<? extends K> map)
```
  - get
```
public int get(K key,
               int defaultValue)
```
    Returns the value for the specified key, or the default value if the key is not in the map.
  - getAndIncrement
```
public int getAndIncrement(K key,
                           int defaultValue,
                           int increment)
```
    Returns the key's current value and increments the stored value. If the key is not in the map, defaultValue + increment is put into the map and defaultValue is returned.
  - remove
```
public int remove(K key,
                  int defaultValue)
```
    Returns the value for the removed key, or the default value if the key is not in the map.
  - notEmpty
```
public boolean notEmpty()
```
    Returns true if the map has one or more items.
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if the map is empty.
  - shrink
```
public void shrink(int maximumCapacity)
```
    Reduces the size of the backing arrays to be the specified capacity / loadFactor, or less. If the capacity is already less, nothing is done. If the map contains more items than the specified capacity, the next highest power of two capacity is used instead.
  - clear
```
public void clear(int maximumCapacity)
```
    Clears the map and reduces the size of the backing arrays to be the specified capacity / loadFactor, if they are larger.
  - clear
```
public void clear()
```
  - containsValue
```
public boolean containsValue(int value)
```
    Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
  - containsKey
```
public boolean containsKey(K key)
```
  - findKey
```
@Null
public K findKey(int value)
```
    Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.
  - ensureCapacity
```
public void ensureCapacity(int additionalCapacity)
```
    Increases the size of the backing array to accommodate the specified number of additional items / loadFactor. Useful before adding many items to avoid multiple backing array resizes.
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object
  - equals
```
public boolean equals(java.lang.Object obj)
```
    Overrides:
    
    equals in class java.lang.Object
  - toString
```
public java.lang.String toString(java.lang.String separator)
```
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - iterator
```
public ObjectIntMap.Entries<K> iterator()
```
    Specified by:
    
    iterator in interface java.lang.Iterable<ObjectIntMap.Entry<K>>
  - entries
```
public ObjectIntMap.Entries<K> entries()
```
    Returns an iterator for the entries in the map. Remove is supported.
    If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the ObjectIntMap.Entries constructor for nested or multithreaded iteration.
  - values
```
public ObjectIntMap.Values values()
```
    Returns an iterator for the values in the map. Remove is supported.
    If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the ObjectIntMap.Values constructor for nested or multithreaded iteration.
  - keys
```
public ObjectIntMap.Keys<K> keys()
```
    Returns an iterator for the keys in the map. Remove is supported.
    If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the ObjectIntMap.Keys constructor for nested or multithreaded iteration.

Class ObjectIntMap<K>

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

size

shift

mask

Constructor Detail

ObjectIntMap

ObjectIntMap

ObjectIntMap

ObjectIntMap

Method Detail

place

put

put

putAll

get

getAndIncrement

remove

notEmpty

isEmpty

shrink

clear

clear

containsValue

containsKey

findKey

ensureCapacity

hashCode

equals

toString

toString

iterator

entries

values

keys