Queue (libGDX Core 1.10.0 API)

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

All Implemented Interfaces:

Iterable<T>
```
public class Queue<T>
extends Object
implements 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 and Description

static class Queue.QueueIterable<T>

static class Queue.QueueIterator<T>

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

Field Summary

Fields
Modifier and Type Field and Description

int size
Number of elements in the queue.

Fields
Modifier and Type	Field and Description
`int`	`size` Number of elements in the queue.

Constructor Summary

Constructors
Constructor and 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, 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 and 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(Object o)`
`boolean`	`equalsIdentity(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.
`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.
`String`	`toString()`
`String`	`toString(String separator)`

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

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

- Field Detail
  - 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,
             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.
  - removeFirst
```
public T removeFirst()
```
    Remove the first item from the queue. (dequeue from head) Always O(1).
    
    Returns:
    
    removed object
    
    Throws:
    
    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:
    
    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:
    
    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:
    
    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:
    
    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 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 Iterable<T>
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - toString
```
public String toString(String separator)
```
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - equalsIdentity
```
public boolean equalsIdentity(Object o)
```
    Uses == for comparison of each item.

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

size

Constructor Detail

Queue

Queue

Queue

Method Detail

addLast

addFirst

ensureCapacity

removeFirst

removeLast

indexOf

removeValue

removeIndex

notEmpty

isEmpty

first

last

get

clear

iterator

toString

toString

hashCode

equals

equalsIdentity