LightweightSet

java.lang.Object
- ohos.utils.LightweightSet<E>

所有已实现的接口:

Iterable<E>, Collection<E>, Set<E>
```
public final class LightweightSet<E>
extends Object
implements Collection<E>, Set<E>
```
Provides a container that implements the Collection and Set interfaces.
The LightweightSet container uses less memory than the HashSet container, but may show poor performance when reaching a large size.
It is recommended that you use this container when less memory is required.
Note: The thread is secure only when data is read from the LightweightSet container.

从以下版本开始:

1

构造器概要

构造器
构造器	说明
`LightweightSet()`	Constructs a default `LightweightSet` container.
`LightweightSet(int capacity)`	Constructs an `LightweightSet` container with a specified capacity.
`LightweightSet(int capacity, boolean useIdentityHash)`	Constructs an `LightweightSet` container with a specified capacity and specifies whether to use the system hash method to map keys.
`LightweightSet(LightweightSet<? extends E> srcLightweightSet)`	Constructs a new `LightweightSet` container using an existing `LightweightSet` container.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`boolean`	`add(E element)`	Adds a specified `element` object to an `LightweightSet` container.
`boolean`	`addAll(Collection<? extends E> collection)`	Adds all objects in a specified `Collection` to an `LightweightSet` container.
`boolean`	`addAll(LightweightSet<? extends E> array)`	Adds all the objects in a specified `LightweightSet` container to the current `LightweightSet` container.
`void`	`clear()`	Clears an `LightweightSet` container.
`boolean`	`contains(Object key)`	Checks whether an `LightweightSet` container has a specified `key`.
`boolean`	`containsAll(Collection<?> collection)`	Checks whether an `LightweightSet` container has all the objects of a specified `Collection`.
`void`	`ensureCapacity(int minimumCapacity)`	Ensures that the capacity of an `LightweightSet` container is greater than or equal to a specified value, and that the container has all the original objects after capacity expansion.
`boolean`	`equals(Object obj)`	Checks whether the objects of an `LightweightSet` container are of the same type as a specified `Object`.
`int`	`hashCode()`	Obtains the hash value of an `LightweightSet` container.
`int`	`indexOf(Object key)`	Obtains the index of a `key` of a specified `Object` type in an `LightweightSet` container.
`boolean`	`isEmpty()`	Checks whether an `LightweightSet` container has no object.
`Iterator<E>`	`iterator()`	Obtains an `Iterator` that can operate the `LightweightSet` container.
`boolean`	`remove(Object obj)`	Deletes an object of a specified `Object` type from an `LightweightSet` container.
`boolean`	`removeAll(Collection<?> collection)`	Deletes all the objects that are contained in a specified `Collection` from an `LightweightSet` container.
`boolean`	`removeAll(LightweightSet<? extends E> array)`	Deletes all the objects that are contained in a specified `LightweightSet` container from an `LightweightSet` container.
`E`	`removeAt(int index)`	Deletes an object at the location identified by `index` from an `LightweightSet` container.
`boolean`	`retainAll(Collection<?> collection)`	Deletes the objects that do not exist in a specified `Collection` from an `LightweightSet` container.
`int`	`size()`	Obtains the number of objects in an `LightweightSet` container.
`Object[]`	`toArray()`	Obtains an array that contains all the objects of an `LightweightSet` container.
`<T> T[]`	`toArray(T[] array)`	Obtains an array that contains all the objects of an `LightweightSet` container.
`String`	`toString()`	Obtains a string that contains all the objects of an `LightweightSet` container.
`E`	`valueAt(int index)`	Obtains the object at the location identified by `index` in an `LightweightSet` container.
`E`	`valueAt(int index, E defaultKey)`	Obtains the object at the location identified by `index` in an `LightweightSet` container.

从接口继承的方法 java.util.Collection
parallelStream, removeIf, stream

从接口继承的方法 java.lang.Iterable
forEach

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

从接口继承的方法 java.util.Set
spliterator

- 构造器详细资料
  - LightweightSet
```
public LightweightSet()
```
    Constructs a default LightweightSet container.
  - LightweightSet
```
public LightweightSet(int capacity)
```
    Constructs an LightweightSet container with a specified capacity.
    
    参数:
    
    capacity - Indicates the capacity of the LightweightSet container to be constructed.
  - LightweightSet
```
public LightweightSet(int capacity,
                      boolean useIdentityHash)
```
    Constructs an LightweightSet container with a specified capacity and specifies whether to use the system hash method to map keys.
    
    参数:
    
    capacity - Indicates the capacity of the LightweightSet container to be constructed.
    
    useIdentityHash - Specifies whether the system hash method is used to map keys. The value true indicates that the System.identityHashCode method is used. The value false indicates that the default hashCode method is used.
  - LightweightSet
```
public LightweightSet(LightweightSet<? extends E> srcLightweightSet)
```
    Constructs a new LightweightSet container using an existing LightweightSet container.
    
    参数:
    
    srcLightweightSet - Indicates an existing LightweightSet container.
- 方法详细资料
  - add
```
public boolean add(E element)
```
    Adds a specified element object to an LightweightSet container.
    
    指定者:
    
    add 在接口中 Collection<E>
    
    指定者:
    
    add 在接口中 Set<E>
    
    参数:
    
    element - Indicates the element object to add.
    
    返回:
    
    Returns true if the element object is added; returns false if the element object already exists in the LightweightSet container.
  - addAll
```
public boolean addAll(LightweightSet<? extends E> array)
```
    Adds all the objects in a specified LightweightSet container to the current LightweightSet container.
    Before the objects are added, the capacity of the current LightweightSet container will be checked and assured.
    
    参数:
    
    array - Indicates the specified LightweightSet container whose objects are to be added to the current LightweightSet container.
    
    返回:
    
    Returns true if any object is added to the current container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if array is null.
  - addAll
```
public boolean addAll(Collection<? extends E> collection)
```
    Adds all objects in a specified Collection to an LightweightSet container.
    
    指定者:
    
    addAll 在接口中 Collection<E>
    
    指定者:
    
    addAll 在接口中 Set<E>
    
    参数:
    
    collection - Indicates the Collection whose objects are to be added to the LightweightSet container.
    
    返回:
    
    Returns true if any object is added to the container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    另请参阅:
    
    Collection.add(Object)
  - clear
```
public void clear()
```
    Clears an LightweightSet container.
    This method makes the LightweightSet container empty.
    
    指定者:
    
    clear 在接口中 Collection<E>
    
    指定者:
    
    clear 在接口中 Set<E>
  - contains
```
public boolean contains(Object key)
```
    Checks whether an LightweightSet container has a specified key.
    
    指定者:
    
    contains 在接口中 Collection<E>
    
    指定者:
    
    contains 在接口中 Set<E>
    
    参数:
    
    key - Indicates the specified key.
    
    返回:
    
    Returns true if the LightweightSet container has the specified key; returns false otherwise.
  - containsAll
```
public boolean containsAll(Collection<?> collection)
```
    Checks whether an LightweightSet container has all the objects of a specified Collection.
    
    指定者:
    
    containsAll 在接口中 Collection<E>
    
    指定者:
    
    containsAll 在接口中 Set<E>
    
    参数:
    
    collection - Indicates the specified Collection.
    
    返回:
    
    Returns true if the LightweightSet container has all the objects of the specified Collection; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    另请参阅:
    
    Collection.contains(Object)
  - ensureCapacity
```
public void ensureCapacity(int minimumCapacity)
```
    Ensures that the capacity of an LightweightSet container is greater than or equal to a specified value, and that the container has all the original objects after capacity expansion.
    
    参数:
    
    minimumCapacity - Indicates the minimum capacity allowed for the LightweightSet container.
  - equals
```
public boolean equals(Object obj)
```
    Checks whether the objects of an LightweightSet container are of the same type as a specified Object.
    
    指定者:
    
    equals 在接口中 Collection<E>
    
    指定者:
    
    equals 在接口中 Set<E>
    
    覆盖:
    
    equals 在类中 Object
    
    参数:
    
    obj - Indicates the Object to be compared with the objects of the LightweightSet container.
    
    返回:
    
    Returns true if the objects of the LightweightSet container are of the same type as the specified Object; returns false otherwise.
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - hashCode
```
public int hashCode()
```
    Obtains the hash value of an LightweightSet container.
    The hash value is the sum of the hash values of all objects of the LightweightSet container.
    If the LightweightSet container has no object, the hash value is 0.
    
    指定者:
    
    hashCode 在接口中 Collection<E>
    
    指定者:
    
    hashCode 在接口中 Set<E>
    
    覆盖:
    
    hashCode 在类中 Object
    
    返回:
    
    Returns the hash value of the LightweightSet container.
    
    另请参阅:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - indexOf
```
public int indexOf(Object key)
```
    Obtains the index of a key of a specified Object type in an LightweightSet container.
    
    参数:
    
    key - Indicates the key of a specified Object type.
    
    返回:
    
    Returns the index of the key in int format.
  - isEmpty
```
public boolean isEmpty()
```
    Checks whether an LightweightSet container has no object.
    
    指定者:
    
    isEmpty 在接口中 Collection<E>
    
    指定者:
    
    isEmpty 在接口中 Set<E>
    
    返回:
    
    Returns true if the LightweightSet container has no object; returns false otherwise.
  - iterator
```
public Iterator<E> iterator()
```
    Obtains an Iterator that can operate the LightweightSet container.
    
    指定者:
    
    iterator 在接口中 Collection<E>
    
    指定者:
    
    iterator 在接口中 Iterable<E>
    
    指定者:
    
    iterator 在接口中 Set<E>
    
    返回:
    
    Returns an Iterator that can operate the LightweightSet container.
  - remove
```
public boolean remove(Object obj)
```
    Deletes an object of a specified Object type from an LightweightSet container.
    
    指定者:
    
    remove 在接口中 Collection<E>
    
    指定者:
    
    remove 在接口中 Set<E>
    
    参数:
    
    obj - Indicates the object to be deleted.
    
    返回:
    
    Returns true if the object is deleted from the LightweightSet container; returns false if the object does not exist in the LightweightSet container.
  - removeAll
```
public boolean removeAll(LightweightSet<? extends E> array)
```
    Deletes all the objects that are contained in a specified LightweightSet container from an LightweightSet container.
    
    参数:
    
    array - Indicates the specified LightweightSet container.
    
    返回:
    
    Returns true if any object is deleted from the LightweightSet container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if array is null.
  - removeAll
```
public boolean removeAll(Collection<?> collection)
```
    Deletes all the objects that are contained in a specified Collection from an LightweightSet container.
    
    指定者:
    
    removeAll 在接口中 Collection<E>
    
    指定者:
    
    removeAll 在接口中 Set<E>
    
    参数:
    
    collection - Indicates the specified Collection.
    
    返回:
    
    Returns true if any object is deleted from the LightweightSet container; returns false otherwise.
    
    另请参阅:
    
    Collection.remove(Object), Collection.contains(Object)
  - removeAt
```
public E removeAt(int index)
```
    Deletes an object at the location identified by index from an LightweightSet container.
    If index is a negative number, the object is located from the reverse direction.
    During the deletion, the system determines whether to expand or reduce capacity of the LightweightSet container. If the number of objects in the container is less than a specified number, the system reduces the capacity of the container.
    
    参数:
    
    index - Identifies the location of an object.
    
    返回:
    
    Returns the object identified by index.
  - retainAll
```
public boolean retainAll(Collection<?> collection)
```
    Deletes the objects that do not exist in a specified Collection from an LightweightSet container.
    
    指定者:
    
    retainAll 在接口中 Collection<E>
    
    指定者:
    
    retainAll 在接口中 Set<E>
    
    参数:
    
    collection - Indicates the specified Collection.
    
    返回:
    
    Returns true if any object is deleted from the LightweightSet container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    另请参阅:
    
    Collection.remove(Object), Collection.contains(Object)
  - toString
```
public String toString()
```
    Obtains a string that contains all the objects of an LightweightSet container.
    An example string is "{1, 2}".
    Objects in the LightweightSet container must support the toString method.
    
    覆盖:
    
    toString 在类中 Object
    
    返回:
    
    Returns a string that contains all the objects of the LightweightSet container.
  - size
```
public int size()
```
    Obtains the number of objects in an LightweightSet container.
    
    指定者:
    
    size 在接口中 Collection<E>
    
    指定者:
    
    size 在接口中 Set<E>
    
    返回:
    
    Returns the number of objects in the LightweightSet container.
  - toArray
```
public Object[] toArray()
```
    Obtains an array that contains all the objects of an LightweightSet container.
    
    指定者:
    
    toArray 在接口中 Collection<E>
    
    指定者:
    
    toArray 在接口中 Set<E>
    
    返回:
    
    Returns an array that contains all the objects of the LightweightSet container.
  - toArray
```
public <T> T[] toArray(T[] array)
```
    Obtains an array that contains all the objects of an LightweightSet container.
    If the capacity of the input array is insufficient, a new array with sufficient capacity will be used.
    
    指定者:
    
    toArray 在接口中 Collection<E>
    
    指定者:
    
    toArray 在接口中 Set<E>
    
    类型参数:
    
    T - the runtime type of the array to contain the collection
    
    参数:
    
    array - Indicates the array that stores all objects of the LightweightSet container.
    
    返回:
    
    Returns an array that contains all the objects of the LightweightSet container.
    
    抛出:
    
    NullPointerException - Throws this exception if array is null.
  - valueAt
```
public E valueAt(int index)
```
    Obtains the object at the location identified by index in an LightweightSet container.
    If index is a negative number, the object is located from the reverse direction.
    
    参数:
    
    index - Identifies the location of an object.
    
    返回:
    
    Returns the object identified by index in the LightweightSet container.
  - valueAt
```
public E valueAt(int index,
                 E defaultKey)
```
    Obtains the object at the location identified by index in an LightweightSet container.
    If index is a negative number, the object is located from the reverse direction.
    If the index is invalid (for example, it is greater than the number of objects in the LightweightSet container or less than 0), defaultKey will be returned.
    
    参数:
    
    index - Identifies the location of an object.
    
    defaultKey - Indicates the default value returned if the specified index is invalid.
    
    返回:
    
    Returns the object identified by index in the LightweightSet container.

类 LightweightSet<E>

构造器概要

方法概要

从接口继承的方法 java.util.Collection

从接口继承的方法 java.lang.Iterable

从类继承的方法 java.lang.Object

从接口继承的方法 java.util.Set

构造器详细资料

LightweightSet

LightweightSet

LightweightSet

LightweightSet

方法详细资料

add

addAll

addAll

clear

contains

containsAll

ensureCapacity

equals

hashCode

indexOf

isEmpty

iterator

remove

removeAll

removeAll

removeAt

retainAll

toString

size

toArray

toArray

valueAt

valueAt