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

All Implemented Interfaces:

java.lang.Iterable<T>
```
public class Queue<T>
extends java.lang.Object
implements java.lang.Iterable<T>
```
A resizable, ordered array of objects with efficient add and remove at the beginning and end. Values in the backing array may wrap back to the beginning, making add and remove at the beginning and end O(1) (unless the backing array needs to resize when adding). Deque functionality is provided via removeLast() and addFirst(Object).

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class Queue.QueueIterable<T>

static class Queue.QueueIterator<T>

Field Summary

Fields
Modifier and Type	Field	Description
`protected int`	`head`	Index of first element.
`int`	`size`	Number of elements in the queue.
`protected int`	`tail`	Index of last element.
`protected T[]`	`values`	Contains the values in the queue.

Constructor Summary

Constructors
Constructor	Description
`Queue()`	Creates a new Queue which can hold 16 values without needing to resize backing array.
`Queue(int initialSize)`	Creates a new Queue which can hold the specified number of values without needing to resize backing array.
`Queue(int initialSize, java.lang.Class<T> type)`	Creates a new Queue which can hold the specified number of values without needing to resize backing array.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addFirst(T object)`	Prepend given object to the head.
`void`	`addLast(T object)`	Append given object to the tail.
`void`	`clear()`	Removes all values from this queue.
`void`	`ensureCapacity(int additional)`	Increases the size of the backing array to accommodate the specified number of additional items.
`boolean`	`equals(java.lang.Object o)`
`boolean`	`equalsIdentity(java.lang.Object o)`	Uses == for comparison of each item.
`T`	`first()`	Returns the first (head) item in the queue (without removing it).
`T`	`get(int index)`	Retrieves the value in queue without removing it.
`int`	`hashCode()`
`int`	`indexOf(T value, boolean identity)`	Returns the index of first occurrence of value in the queue, or -1 if no such value exists.
`boolean`	`isEmpty()`	Returns true if the queue is empty.
`java.util.Iterator<T>`	`iterator()`	Returns an iterator for the items in the queue.
`T`	`last()`	Returns the last (tail) item in the queue (without removing it).
`boolean`	`notEmpty()`	Returns true if the queue has one or more items.
`T`	`removeFirst()`	Remove the first item from the queue.
`T`	`removeIndex(int index)`	Removes and returns the item at the specified index.
`T`	`removeLast()`	Remove the last item from the queue.
`boolean`	`removeValue(T value, boolean identity)`	Removes the first instance of the specified value in the queue.
`protected void`	`resize(int newSize)`	Resize backing array.
`java.lang.String`	`toString()`
`java.lang.String`	`toString(java.lang.String separator)`

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
  - values
```
protected T[] values
```
    Contains the values in the queue. Head and tail indices go in a circle around this array, wrapping at the end.
  - head
```
protected int head
```
    Index of first element. Logically smaller than tail. Unless empty, it points to a valid element inside queue.
  - tail
```
protected int tail
```
    Index of last element. Logically bigger than head. Usually points to an empty position, but points to the head when full (size == values.length).
  - size
```
public int size
```
    Number of elements in the queue.
- Constructor Detail
  - Queue
```
public Queue()
```
    Creates a new Queue which can hold 16 values without needing to resize backing array.
  - Queue
```
public Queue(int initialSize)
```
    Creates a new Queue which can hold the specified number of values without needing to resize backing array.
  - Queue
```
public Queue(int initialSize,
             java.lang.Class<T> type)
```
    Creates a new Queue which can hold the specified number of values without needing to resize backing array. This creates backing array of the specified type via reflection, which is necessary only when accessing the backing array directly.
- Method Detail
  - addLast
```
public void addLast(@Null
                    T object)
```
    Append given object to the tail. (enqueue to tail) Unless backing array needs resizing, operates in O(1) time.
    
    Parameters:
    
    object - can be null
  - addFirst
```
public void addFirst(@Null
                     T object)
```
    Prepend given object to the head. (enqueue to head) Unless backing array needs resizing, operates in O(1) time.
    
    Parameters:
    
    object - can be null
    
    See Also:
    
    addLast(Object)
  - ensureCapacity
```
public void ensureCapacity(int additional)
```
    Increases the size of the backing array to accommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes.
  - resize
```
protected void resize(int newSize)
```
    Resize backing array. newSize must be bigger than current size.
  - removeFirst
```
public T removeFirst()
```
    Remove the first item from the queue. (dequeue from head) Always O(1).
    
    Returns:
    
    removed object
    
    Throws:
    
    java.util.NoSuchElementException - when queue is empty
  - removeLast
```
public T removeLast()
```
    Remove the last item from the queue. (dequeue from tail) Always O(1).
    
    Returns:
    
    removed object
    
    Throws:
    
    java.util.NoSuchElementException - when queue is empty
    
    See Also:
    
    removeFirst()
  - indexOf
```
public int indexOf(T value,
                   boolean identity)
```
    Returns the index of first occurrence of value in the queue, or -1 if no such value exists.
    
    Parameters:
    
    identity - If true, == comparison will be used. If false, .equals() comparison will be used.
    
    Returns:
    
    An index of first occurrence of value in queue or -1 if no such value exists
  - removeValue
```
public boolean removeValue(T value,
                           boolean identity)
```
    Removes the first instance of the specified value in the queue.
    
    Parameters:
    
    identity - If true, == comparison will be used. If false, .equals() comparison will be used.
    
    Returns:
    
    true if value was found and removed, false otherwise
  - removeIndex
```
public T removeIndex(int index)
```
    Removes and returns the item at the specified index.
  - notEmpty
```
public boolean notEmpty()
```
    Returns true if the queue has one or more items.
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if the queue is empty.
  - first
```
public T first()
```
    Returns the first (head) item in the queue (without removing it).
    
    Throws:
    
    java.util.NoSuchElementException - when queue is empty
    
    See Also:
    
    addFirst(Object), removeFirst()
  - last
```
public T last()
```
    Returns the last (tail) item in the queue (without removing it).
    
    Throws:
    
    java.util.NoSuchElementException - when queue is empty
    
    See Also:
    
    addLast(Object), removeLast()
  - get
```
public T get(int index)
```
    Retrieves the value in queue without removing it. Indexing is from the front to back, zero based. Therefore get(0) is the same as first().
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - when the index is negative or >= size
  - clear
```
public void clear()
```
    Removes all values from this queue. Values in backing array are set to null to prevent memory leak, so this operates in O(n).
  - iterator
```
public java.util.Iterator<T> iterator()
```
    Returns an iterator for the items in the queue. Remove is supported.
    If Collections.allocateIterators is false, the same iterator instance is returned each time this method is called. Use the Queue.QueueIterator constructor for nested or multithreaded iteration.
    
    Specified by:
    
    iterator in interface java.lang.Iterable<T>
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - toString
```
public java.lang.String toString(java.lang.String separator)
```
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object
  - equals
```
public boolean equals(java.lang.Object o)
```
    Overrides:
    
    equals in class java.lang.Object
  - equalsIdentity
```
public boolean equalsIdentity(java.lang.Object o)
```
    Uses == for comparison of each item.

Modifier and Type	Class	Description
`static class`	`Queue.QueueIterable<T>`
`static class`	`Queue.QueueIterator<T>`

Class Queue<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

values

head

tail

size

Constructor Detail

Queue

Queue

Queue

Method Detail

addLast

addFirst

ensureCapacity

resize

removeFirst

removeLast

indexOf

removeValue

removeIndex

notEmpty

isEmpty

first

last

get

clear

iterator

toString

toString

hashCode

equals

equalsIdentity