LightweightMap

java.lang.Object
- ohos.utils.LightweightMap<K,V>

所有已实现的接口:

Map<K,V>
```
public final class LightweightMap<K,V>
extends Object
implements Map<K,V>
```
Provides a container that implements the Map interfaces.
The LightweightMap container uses less memory than the HashMap 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 LightweightMap container.

从以下版本开始:

1

嵌套类概要
- 从接口继承的嵌套类/接口 java.util.Map
  Map.Entry<K,V>

构造器概要

构造器
构造器	说明
`LightweightMap()`	Constructs a default `LightweightMap` container.
`LightweightMap(int capacity)`	Constructs an `LightweightMap` container with a specified capacity.
`LightweightMap(int capacity, boolean useIdentityHash)`	Constructs an `LightweightMap` container with a specified capacity and specifies whether to use the system hash method.
`LightweightMap(LightweightMap<? extends K,? extends V> srcLightweightMap)`	Constructs a new `LightweightMap` container using an existing `LightweightMap` 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
`void`	`clear()`	Deletes all key-value pair mappings in an `LightweightMap` container.
`boolean`	`containsAll(Collection<?> collection)`	Checks whether an `LightweightMap` container has all the objects in a specified `Collection` object.
`boolean`	`containsKey(Object key)`	Checks whether an `LightweightMap` container has a key that is the same as a specified `key`.
`boolean`	`containsValue(Object value)`	Checks whether an `LightweightMap` container has a value that is the same as a specified `value`.
`void`	`ensureCapacity(int minimumCapacity)`	Ensures that the capacity of an `LightweightMap` container is greater than or equal to a specified value, and that the container has all the original objects after capacity expansion.
`Set<Map.Entry<K,V>>`	`entrySet()`	Obtains a `Set` object that contains all key-value pairs in an `LightweightMap` container.
`V`	`get(Object key)`	Obtains the value equal to a specified `key` in an `LightweightMap` container.
`int`	`indexOfKey(Object key)`	Obtains the `index` of the key equal to a specified `key` in an `LightweightMap` container.
`int`	`indexOfValue(Object value)`	Obtains the `index` of the value equal to a specified `value` in an `LightweightMap` container.
`boolean`	`isEmpty()`	Checks whether an `LightweightMap` container has no key-value pair.
`K`	`keyAt(int index)`	Obtains the key at the location identified by `index` in an `LightweightMap` container.
`Set<K>`	`keySet()`	Obtains a `Set` object that contains all the keys of an `LightweightMap` container.
`V`	`put(K key, V value)`	Saves a key-value pair to an `LightweightMap` container.
`void`	`putAll(Map<? extends K,? extends V> map)`	Adds all objects of a specified `Map` container to an `LightweightMap` container.
`void`	`putAll(LightweightMap<? extends K,? extends V> arrayMap)`	Adds all objects of a specified `LightweightMap` container to another `LightweightMap` container.
`V`	`remove(Object key)`	Deletes a key-value pair whose key is the same as a specified `key` from an `LightweightMap` container.
`boolean`	`removeAll(Collection<?> collection)`	Deletes key-value pairs with the same objects as a specified `Collection` from an `LightweightMap` container.
`V`	`removeAt(int index)`	Deletes a key-value pair at the location identified by `index` from an `LightweightMap` container.
`boolean`	`retainAll(Collection<?> collection)`	Deletes the key-value pairs that do not exist in a specified `Collection` object from an `LightweightMap` container.
`V`	`setValueAt(int index, V value)`	Sets the value identified by `index` in an `LightweightMap` container to a specified `value`.
`int`	`size()`	Obtains the number of key-value pairs stored in an `LightweightMap` container.
`String`	`toString()`	Obtains a string that contains all the keys and values in an `LightweightMap` container.
`V`	`valueAt(int index)`	Obtains the value identified by `index` in an `LightweightMap` container.
`Collection<V>`	`values()`	Obtains a `Collection` object that contains all values of an `LightweightMap` container.

从接口继承的方法 java.util.Map
compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

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

- 构造器详细资料
  - LightweightMap
```
public LightweightMap()
```
    Constructs a default LightweightMap container.
    
    从以下版本开始:
    
    1
  - LightweightMap
```
public LightweightMap(int capacity)
```
    Constructs an LightweightMap container with a specified capacity.
    The number of key-value pairs of the constructed LightweightMap container can hold is determined by the specified capacity.
    
    参数:
    
    capacity - Indicates the capacity of the LightweightMap container to be constructed.
    
    从以下版本开始:
    
    1
  - LightweightMap
```
public LightweightMap(int capacity,
                      boolean useIdentityHash)
```
    Constructs an LightweightMap container with a specified capacity and specifies whether to use the system hash method.
    
    参数:
    
    capacity - Indicates the capacity of the LightweightMap 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.
    
    从以下版本开始:
    
    1
  - LightweightMap
```
public LightweightMap(LightweightMap<? extends K,? extends V> srcLightweightMap)
```
    Constructs a new LightweightMap container using an existing LightweightMap container.
    
    参数:
    
    srcLightweightMap - Indicates an existing LightweightMap container.
    
    从以下版本开始:
    
    1
- 方法详细资料
  - clear
```
public void clear()
```
    Deletes all key-value pair mappings in an LightweightMap container.
    This method makes the LightweightMap container empty.
    
    指定者:
    
    clear 在接口中 Map<K,V>
    
    从以下版本开始:
    
    1
  - containsAll
```
public boolean containsAll(Collection<?> collection)
```
    Checks whether an LightweightMap container has all the objects in a specified Collection object.
    
    参数:
    
    collection - Indicates the specified Collection object.
    
    返回:
    
    Returns true if the LightweightMap container has all the objects in the specified Collection object; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    从以下版本开始:
    
    1
  - containsKey
```
public boolean containsKey(Object key)
```
    Checks whether an LightweightMap container has a key that is the same as a specified key.
    
    指定者:
    
    containsKey 在接口中 Map<K,V>
    
    参数:
    
    key - Indicates the specified key.
    
    返回:
    
    Returns true if the LightweightMap container has a key that is the same as the specified key; returns false otherwise.
    
    从以下版本开始:
    
    1
  - containsValue
```
public boolean containsValue(Object value)
```
    Checks whether an LightweightMap container has a value that is the same as a specified value.
    
    指定者:
    
    containsValue 在接口中 Map<K,V>
    
    参数:
    
    value - Indicates the specified value.
    
    返回:
    
    Returns true if the LightweightMap container has a value that is the same as the specified value; returns false otherwise.
    
    从以下版本开始:
    
    1
  - ensureCapacity
```
public void ensureCapacity(int minimumCapacity)
```
    Ensures that the capacity of an LightweightMap 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 LightweightMap container.
    
    从以下版本开始:
    
    1
  - entrySet
```
public Set<Map.Entry<K,V>> entrySet()
```
    Obtains a Set object that contains all key-value pairs in an LightweightMap container.
    The key-value pairs are stored in the Map.Entry format.
    
    指定者:
    
    entrySet 在接口中 Map<K,V>
    
    返回:
    
    Returns a Set object that contains all key-value pairs in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - get
```
public V get(Object key)
```
    Obtains the value equal to a specified key in an LightweightMap container.
    
    指定者:
    
    get 在接口中 Map<K,V>
    
    参数:
    
    key - Indicates the specified key.
    
    返回:
    
    Returns the value equal to the specified key; returns null if the specified key does not exist in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - indexOfKey
```
public int indexOfKey(Object key)
```
    Obtains the index of the key equal to a specified key in an LightweightMap container.
    
    参数:
    
    key - Indicates the specified key.
    
    返回:
    
    Returns the requested index in int format.
    
    从以下版本开始:
    
    1
  - indexOfValue
```
public int indexOfValue(Object value)
```
    Obtains the index of the value equal to a specified value in an LightweightMap container.
    
    参数:
    
    value - Indicates the specified value.
    
    返回:
    
    Returns the requested index in int format.
    
    从以下版本开始:
    
    1
  - isEmpty
```
public boolean isEmpty()
```
    Checks whether an LightweightMap container has no key-value pair.
    
    指定者:
    
    isEmpty 在接口中 Map<K,V>
    
    返回:
    
    Returns true if the LightweightMap container has no key-value pair; returns false otherwise.
    
    从以下版本开始:
    
    1
  - keyAt
```
public K keyAt(int index)
```
    Obtains the key at the location identified by index in an LightweightMap container.
    If index is a negative number, the key is located from the reverse direction.
    
    参数:
    
    index - Identifies the location of a key.
    
    返回:
    
    Returns the key identified by index in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - keySet
```
public Set<K> keySet()
```
    Obtains a Set object that contains all the keys of an LightweightMap container.
    
    指定者:
    
    keySet 在接口中 Map<K,V>
    
    返回:
    
    Returns the Set object that contains all the keys in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - put
```
public V put(K key,
             V value)
```
    Saves a key-value pair to an LightweightMap container.
    If the key of the key-value pair already exists in the LightweightMap container, the existing value of the key is overwritten by the new value.
    If the capacity of the LightweightMap container has been used up, it will be automatically expanded.
    
    指定者:
    
    put 在接口中 Map<K,V>
    
    参数:
    
    key - Indicates the key of the key-value pair to be saved.
    
    value - Indicates the value of the key-value pair to be saved.
    
    返回:
    
    Returns the existing value of the key before this operation is performed; returns null if the key is not contained in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - putAll
```
public void putAll(LightweightMap<? extends K,? extends V> arrayMap)
```
    Adds all objects of a specified LightweightMap container to another LightweightMap container.
    
    参数:
    
    arrayMap - Indicates the specified LightweightMap container whose objects are to be added to another LightweightMap container.
    
    抛出:
    
    NullPointerException - Throws this exception if arrayMap is null.
    
    从以下版本开始:
    
    1
  - putAll
```
public void putAll(Map<? extends K,? extends V> map)
```
    Adds all objects of a specified Map container to an LightweightMap container.
    
    指定者:
    
    putAll 在接口中 Map<K,V>
    
    参数:
    
    map - Indicates the specified Map container whose objects are to be added to the LightweightMap container.
    
    抛出:
    
    NullPointerException - Throws this exception if map is null.
    
    从以下版本开始:
    
    1
  - remove
```
public V remove(Object key)
```
    Deletes a key-value pair whose key is the same as a specified key from an LightweightMap container.
    
    指定者:
    
    remove 在接口中 Map<K,V>
    
    参数:
    
    key - Indicates the specified key.
    
    返回:
    
    Returns the value of the specified key if the key-value pair is deleted; returns null if the key is not contained in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - removeAll
```
public boolean removeAll(Collection<?> collection)
```
    Deletes key-value pairs with the same objects as a specified Collection from an LightweightMap container.
    
    参数:
    
    collection - Indicates the specified Collection which defines the mappings to be deleted.
    
    返回:
    
    Returns true if any object is deleted from the LightweightMap container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    从以下版本开始:
    
    1
  - removeAt
```
public V removeAt(int index)
```
    Deletes a key-value pair at the location identified by index from an LightweightMap container.
    If index is a negative number, the key-value pair is located from the reverse direction.
    During the deletion, the system determines whether to expand or reduce capacity of the LightweightMap 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 a key-value pair.
    
    返回:
    
    Returns the key identified by index.
    
    从以下版本开始:
    
    1
  - retainAll
```
public boolean retainAll(Collection<?> collection)
```
    Deletes the key-value pairs that do not exist in a specified Collection object from an LightweightMap container.
    
    参数:
    
    collection - Indicates the specified Collection object.
    
    返回:
    
    Returns true if any key-value pair is deleted from the LightweightMap container; returns false otherwise.
    
    抛出:
    
    NullPointerException - Throws this exception if collection is null.
    
    从以下版本开始:
    
    1
  - setValueAt
```
public V setValueAt(int index,
                    V value)
```
    Sets the value identified by index in an LightweightMap container to a specified value.
    
    参数:
    
    index - Identifies the location of a value.
    
    value - Indicates the value to be set.
    
    返回:
    
    Returns the old value identified by index.
    
    抛出:
    
    IndexOutOfBoundsException - Throws this exception if the specified index is beyond the valid range.
    
    从以下版本开始:
    
    1
  - size
```
public int size()
```
    Obtains the number of key-value pairs stored in an LightweightMap container.
    
    指定者:
    
    size 在接口中 Map<K,V>
    
    返回:
    
    Returns the number of key-value pairs stored in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - toString
```
public String toString()
```
    Obtains a string that contains all the keys and values in an LightweightMap container.
    An example string is "{1: "one", 2: "two"}".
    The keys and values must support the toString method.
    
    覆盖:
    
    toString 在类中 Object
    
    返回:
    
    Returns a string that contains all the keys and values in the LightweightMap container.
    
    从以下版本开始:
    
    1
  - valueAt
```
public V valueAt(int index)
```
    Obtains the value identified by index in an LightweightMap container.
    If index is a negative number, the value is located from the reverse direction.
    
    参数:
    
    index - Identifies the location of a value.
    
    返回:
    
    Returns the value identified by index.
    
    从以下版本开始:
    
    1
  - values
```
public Collection<V> values()
```
    Obtains a Collection object that contains all values of an LightweightMap container.
    
    指定者:
    
    values 在接口中 Map<K,V>
    
    返回:
    
    Returns a Collection object that contains all values of an LightweightMap container.
    
    从以下版本开始:
    
    1

类 LightweightMap<K,V>

嵌套类概要

从接口继承的嵌套类/接口 java.util.Map

构造器概要

方法概要

从接口继承的方法 java.util.Map

从类继承的方法 java.lang.Object

构造器详细资料

LightweightMap

LightweightMap

LightweightMap

LightweightMap

方法详细资料

clear

containsAll

containsKey

containsValue

ensureCapacity

entrySet

get

indexOfKey

indexOfValue

isEmpty

keyAt

keySet

put

putAll

putAll

remove

removeAll

removeAt

retainAll

setValueAt

size

toString

valueAt

values