java.lang.Object
- com.badlogic.gdx.utils.ObjectSet<T>

All Implemented Interfaces:

java.lang.Iterable<T>

Direct Known Subclasses:

OrderedSet
```
public class ObjectSet<T>
extends java.lang.Object
implements java.lang.Iterable<T>
```
An unordered set where the keys are objects. 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.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class ObjectSet.ObjectSetIterator<K>

Field Summary

Fields
Modifier and Type	Field	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	Description
`ObjectSet()`	Creates a new set with an initial capacity of 51 and a load factor of 0.8.
`ObjectSet(int initialCapacity)`	Creates a new set with a load factor of 0.8.
`ObjectSet(int initialCapacity, float loadFactor)`	Creates a new set with the specified initial capacity and load factor.
`ObjectSet(ObjectSet<? extends T> set)`	Creates a new set identical to the specified set.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`add(T key)`	Returns true if the key was added to the set or false if it was already in the set.
`void`	`addAll(Array<? extends T> array)`
`void`	`addAll(Array<? extends T> array, int offset, int length)`
`void`	`addAll(ObjectSet<T> set)`
`boolean`	`addAll(T... array)`
`boolean`	`addAll(T[] array, int offset, int length)`
`void`	`clear()`	Clears the set, leaving the backing arrays at the current capacity.
`void`	`clear(int maximumCapacity)`	Clears the set and reduces the size of the backing arrays to be the specified capacity / loadFactor, if they are larger.
`boolean`	`contains(T key)`
`void`	`ensureCapacity(int additionalCapacity)`	Increases the size of the backing array to accommodate the specified number of additional items / loadFactor.
`boolean`	`equals(java.lang.Object obj)`
`T`	`first()`
`T`	`get(T key)`
`int`	`hashCode()`
`boolean`	`isEmpty()`	Returns true if the set is empty.
`ObjectSet.ObjectSetIterator<T>`	`iterator()`	Returns an iterator for the keys in the set.
`boolean`	`notEmpty()`	Returns true if the set has one or more items.
`protected int`	`place(T item)`	Returns an index >= 0 and <= `mask` for the specified `item`.
`boolean`	`remove(T key)`	Returns true if the key was removed.
`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)`
`static <T> ObjectSet<T>`	`with(T... array)`

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
  - ObjectSet
```
public ObjectSet()
```
    Creates a new set with an initial capacity of 51 and a load factor of 0.8.
  - ObjectSet
```
public ObjectSet(int initialCapacity)
```
    Creates a new set with a load factor of 0.8.
    
    Parameters:
    
    initialCapacity - The backing array size is initialCapacity / loadFactor, increased to the next power of two.
  - ObjectSet
```
public ObjectSet(int initialCapacity,
                 float loadFactor)
```
    Creates a new set with the specified initial capacity and load factor. This set will hold initialCapacity items before growing the backing table.
    
    Parameters:
    
    initialCapacity - The backing array size is initialCapacity / loadFactor, increased to the next power of two.
  - ObjectSet
```
public ObjectSet(ObjectSet<? extends T> set)
```
    Creates a new set identical to the specified set.
- Method Detail
  - place
```
protected int place(T 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;
  - add
```
public boolean add(T key)
```
    Returns true if the key was added to the set or false if it was already in the set. If this set already contains the key, the call leaves the set unchanged and returns false.
  - addAll
```
public void addAll(Array<? extends T> array)
```
  - addAll
```
public void addAll(Array<? extends T> array,
                   int offset,
                   int length)
```
  - addAll
```
public boolean addAll(T... array)
```
  - addAll
```
public boolean addAll(T[] array,
                      int offset,
                      int length)
```
  - addAll
```
public void addAll(ObjectSet<T> set)
```
  - remove
```
public boolean remove(T key)
```
    Returns true if the key was removed.
  - notEmpty
```
public boolean notEmpty()
```
    Returns true if the set has one or more items.
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if the set 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 set 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 set and reduces the size of the backing arrays to be the specified capacity / loadFactor, if they are larger. The reduction is done by allocating new arrays, though for large arrays this can be faster than clearing the existing array.
  - clear
```
public void clear()
```
    Clears the set, leaving the backing arrays at the current capacity. When the capacity is high and the population is low, iteration can be unnecessarily slow. clear(int) can be used to reduce the capacity.
  - contains
```
public boolean contains(T key)
```
  - get
```
@Null
public T get(T key)
```
  - first
```
public T first()
```
  - 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()
```
    Overrides:
    
    toString in class java.lang.Object
  - toString
```
public java.lang.String toString(java.lang.String separator)
```
  - iterator
```
public ObjectSet.ObjectSetIterator<T> iterator()
```
    Returns an iterator for the keys in the set. Remove is supported.
    If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the ObjectSet.ObjectSetIterator constructor for nested or multithreaded iteration.
    
    Specified by:
    
    iterator in interface java.lang.Iterable<T>
  - with
```
public static <T> ObjectSet<T> with(T... array)
```

Class ObjectSet<T>

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

ObjectSet

ObjectSet

ObjectSet

ObjectSet

Method Detail

place

add

addAll

addAll

addAll

addAll

addAll

remove

notEmpty

isEmpty

shrink

clear

clear

contains

get

first

ensureCapacity

hashCode

equals

toString

toString

iterator

with