Struct NativeList<T>

An unmanaged, resizable list.

Namespace: Unity.Collections
Syntax
public struct NativeList<T> : IEnumerable<T>, IEnumerable, IDisposable where T : struct
Type Parameters
Name Description
T

The type of the elements in the container.

Constructors

NativeList(Allocator)

Constructs a new list using the specified type of memory allocation.

Declaration
public NativeList(Allocator allocator)
Parameters
Type Name Description
Allocator allocator

A member of the Unity.Collections.Allocator enumeration.
Remarks

The list initially has a capacity of one. To avoid reallocating memory for the list, specify sufficient capacity up front.

NativeList(Int32, Allocator)

Constructs a new list with the specified initial capacity and type of memory allocation.

Declaration
public NativeList(int initialCapacity, Allocator allocator)
Parameters
Type Name Description
Int32 initialCapacity

The initial capacity of the list. If the list grows larger than its capacity, the internal array is copied to a new, larger array.
Allocator allocator

A member of the Unity.Collections.Allocator enumeration.

Properties

Capacity

The number of items that can fit in the list.

Declaration
public int Capacity { get; set; }
Property Value
Type Description
Int32

The number of items that the list can hold before it resizes its internal storage.
Remarks

Capacity specifies the number of items the list can currently hold. You can change Capacity to fit more or fewer items. Changing Capacity creates a new array of the specified size, copies the old array to the new one, and then deallocates the original array memory. You cannot change the Capacity to a size smaller than Length (remove unwanted elements from the list first).

Exceptions
Type Condition
ArgumentOutOfRangeException

Thrown if Capacity is set smaller than Length.

IsCreated

Reports whether memory for the container is allocated.

Declaration
public bool IsCreated { get; }
Property Value
Type Description
Boolean

True if this container object's internal storage has been allocated.
Remarks

Note that the container storage is not created if you use the default constructor. You must specify at least an allocation type to construct a usable container.

Item[Int32]

Retrieve a member of the contaner by index.

Declaration
public T this[int index] { get; set; }
Parameters
Type Name Description
Int32 index

The zero-based index into the list.
Property Value
Type Description
T

The list item at the specified index.
Exceptions
Type Condition
IndexOutOfRangeException

Thrown if index is negative or >= to Length.

Length

The current number of items in the list.

Declaration
public int Length { get; }
Property Value
Type Description
Int32

The item count.

Methods

Add(T)

Adds an element to the list.

Declaration
public void Add(T value)
Parameters
Type Name Description
T value
Remarks

If the list has reached its current capacity, it copies the original, internal array to a new, larger array, and then deallocates the original.

AddNoResize(T)

Adds an element to the list.

Declaration
public void AddNoResize(T value)
Parameters
Type Name Description
T value

The value to be added at the end of the list.
Remarks

If the list has reached its current capacity, internal array won't be resized, and exception will be thrown.

AddRange(NativeArray<T>)

Adds the elements of a NativeArray to this list.

Declaration
public void AddRange(NativeArray<T> elements)
Parameters
Type Name Description
NativeArray<T> elements

The items to add.

AddRange(Void*, Int32)

Adds elements from a buffer to this list.

Declaration
public void AddRange(void *elements, int count)
Parameters
Type Name Description
Void* elements

A pointer to the buffer.
Int32 count

The number of elements to add to the list.
Exceptions
Type Condition
ArgumentOutOfRangeException

Thrown if count is negative.

AddRangeNoResize(Void*, Int32)

Adds elements from a buffer to this list.

Declaration
public void AddRangeNoResize(void *ptr, int length)
Parameters
Type Name Description
Void* ptr

A pointer to the buffer.
Int32 length

The number of elements to add to the list.
Remarks

If the list has reached its current capacity, internal array won't be resized, and exception will be thrown.

Exceptions
Type Condition
ArgumentOutOfRangeException

Thrown if length is negative.

AddRangeNoResize(NativeList<T>)

Adds elements from a list to this list.

Declaration
public void AddRangeNoResize(NativeList<T> list)
Parameters
Type Name Description
NativeList<T> list
Remarks

If the list has reached its current capacity, internal array won't be resized, and exception will be thrown.

AsArray()

This list as a NativeArray.

Declaration
public NativeArray<T> AsArray()
Returns
Type Description
NativeArray<T>

A NativeArray "view" of the list.
Remarks

The array is not a copy; it references the same memory as the original list. You can use the NativeArray API to manipulate the list.

AsDeferredJobArray()

Provides a NativeArray that you can pass into a job whose contents can be modified by a previous job.

Declaration
public NativeArray<T> AsDeferredJobArray()
Returns
Type Description
NativeArray<T>

A NativeArray that can be passed to one job as a "promise" that is fulfilled by a previous job.
Remarks

Pass a deferred array to a job when the list is populated or modified by a previous job. Using a deferred array allows you to schedule both jobs at the same time. (Without a deferred array, you would have to wait for the results of the first job before you scheduling the second.)

Examples

The following example populates a list with integers in one job and passes that data to a second job as a deferred array. If you tried to pass the list directly to the second job, that job would get the contents of the list at the time you schedule the job and would not see any modifications made to the list by the first job.

using UnityEngine;
using Unity.Jobs;
using Unity.Collections;

public class DeferredArraySum : MonoBehaviour
{
   public struct ListPopulatorJob : IJob
   {
       public NativeList<int> list;

       public void Execute()
       {
           for (int i = list.Length; i < list.Capacity; i++)
           {
               list.Add(i);
           }
       }
   }

   public struct ArraySummerJob : IJob
   {
       [ReadOnly] public NativeArray<int> deferredArray;
       public NativeArray<int> sum;

       public void Execute()
       {
           sum[0] = 0;
           for (int i = 0; i < deferredArray.Length; i++)
           {
               sum[0] += deferredArray[i];
           }
       }
   }

   void Start()
   {
       var deferredList = new NativeList<int>(100, Allocator.TempJob);

       var populateJob = new ListPopulatorJob()
       {
           list = deferredList
       };

       var output = new NativeArray<int>(1, Allocator.TempJob);
       var sumJob = new ArraySummerJob()
       {
           deferredArray = deferredList.AsDeferredJobArray(),
           sum = output
       };

       var populateJobHandle = populateJob.Schedule();
       var sumJobHandle = sumJob.Schedule(populateJobHandle);

       sumJobHandle.Complete();

       Debug.Log("Result: " + output[0]);

       deferredList.Dispose();
       output.Dispose();
   }
}

AsParallelWriter()

Returns parallel writer instance.

Declaration
public NativeList<T>.ParallelWriter AsParallelWriter()
Returns
Type Description
NativeList.ParallelWriter<>

Clear()

Clears the list.

Declaration
public void Clear()
Remarks

List Capacity remains unchanged.

CopyFrom(T[])

Overwrites this list with the elements of an array.

Declaration
public void CopyFrom(T[] array)
Parameters
Type Name Description
T[] array

A managed array or NativeArray to copy into this list.

Dispose()

Disposes of this container and deallocates its memory immediately.

Declaration
public void Dispose()

Dispose(JobHandle)

Safely disposes of this container and deallocates its memory when the jobs that use it have completed.

Declaration
public JobHandle Dispose(JobHandle inputDeps)
Parameters
Type Name Description
JobHandle inputDeps

The job handle or handles for any scheduled jobs that use this container.
Returns
Type Description
JobHandle

A new job handle containing the prior handles as well as the handle for the job that deletes the container.
Remarks

You can call this function dispose of the container immediately after scheduling the job. Pass the JobHandle returned by the Job.Schedule method using the jobHandle parameter so the job scheduler can dispose the container after all jobs using it have run.

GetEnumerator()

Declaration
public NativeArray<T>.Enumerator GetEnumerator()
Returns
Type Description
NativeArray.Enumerator<>

RemoveAtSwapBack(Int32)

Truncates the list by replacing the item at the specified index with the last item in the list. The list is shortened by one.

Declaration
public void RemoveAtSwapBack(int index)
Parameters
Type Name Description
Int32 index

The index of the item to delete.
Exceptions
Type Condition
ArgumentOutOfRangeException

If index is negative or >= Length.

Resize(Int32, NativeArrayOptions)

Changes the list length, resizing if necessary.

Declaration
public void Resize(int length, NativeArrayOptions options)
Parameters
Type Name Description
Int32 length

The new length of the list.
NativeArrayOptions options

Memory should be cleared on allocation or left uninitialized.

ResizeUninitialized(Int32)

Changes the container length, resizing if necessary, without initializing memory.

Declaration
public void ResizeUninitialized(int length)
Parameters
Type Name Description
Int32 length

The new length of the container.

ToArray()

A copy of this list as a NativeArray.

Declaration
public T[] ToArray()
Returns
Type Description
T[]

A NativeArray containing copies of all the items in the list.

ToArray(Allocator)

A copy of this list as a NativeArray allocated with the specified type of memory.

Declaration
public NativeArray<T> ToArray(Allocator allocator)
Parameters
Type Name Description
Allocator allocator

A member of the Unity.Collections.Allocator enumeration.
Returns
Type Description
NativeArray<T>

A NativeArray containing copies of all the items in the list.

Operators

Implicit(NativeList<T> to NativeArray<T>)

This list as a NativeArray.

Declaration
public static implicit operator NativeArray<T>(NativeList<T> nativeList)
Parameters
Type Name Description
NativeList<T> nativeList

A NativeList instance.
Returns
Type Description
NativeArray<T>

A NativeArray containing all the items in the list.
Remarks

The array is not a copy; it references the same memory as the original list.

Extension Methods