TwinCollection Class

Package:

com.microsoft.azure.sdk.iot.service.twin

• java.lang.Object
• • java.util.HashMap<String, Object>
  • • com.microsoft.azure.sdk.iot.service.twin.TwinCollection

public class TwinCollection

Representation of a single Twin collection.

The TwinCollection is an extension of aHashMap  ofString  and Object  that contain individual and general versioning mechanism.

By the Twin definition, theObject  can contain types ofBoolean  , Number  ,String  ,Object  , or a sub-TwinCollection, but it cannot be types defined by the user or arrays.

A TwinCollection can contain up to 5 levels of sub TwinCollections. Once the TwinCollection is a extension of theHashMap  , both TwinCollection as well as its sub-TwinCollections can be casted to Map of String and Object.

The collection will be represented in the rest API as a JSON in the body. It can or cannot contain the metadata (identified by the $ character at the beginning of the key.

Because of the Twin metadata, the character $ is not allowed in the entry key.

For instance, the following JSON is a valid TwinCollection with its metadata.

{
        "Color":"White",
        "MaxSpeed":{
            "Value":500,
            "NewValue":300
        },
        "$metadata":{
            "$lastUpdated":"2017-09-21T02:07:44.238Z",
            "$lastUpdatedVersion":4,
            "Color":{
                "$lastUpdated":"2017-09-21T02:07:44.238Z",
                "$lastUpdatedVersion":4,
            },
            "MaxSpeed":{
                "$lastUpdated":"2017-09-21T02:07:44.238Z",
                "$lastUpdatedVersion":4,
                "Value":{
                    "$lastUpdated":"2017-09-21T02:07:44.238Z",
                    "$lastUpdatedVersion":4
                },
                "NewValue":{
                    "$lastUpdated":"2017-09-21T02:07:44.238Z",
                    "$lastUpdatedVersion":4
                }
            }
        },
        "$version":4
    }
    

This class exposes the Twin collection with or without metadata as a Map here user can get both the value and the metadata. For instance, in the above TwinCollection, get(Object) for Color will return White and the getTwinMetadata(String key) for Color will return the Object TwinMetadata that contain getLastUpdated() that will returns theDate  for example 2017-09-21T02:07:44.238Z, getLastUpdatedBy() that will return theString  for example testConfig, getLastUpdatedByDigest() that will return theString  for example 637570515479675333, and getLastUpdatedVersion() that will return theInteger  for example 4.

For the nested TwinCollection, you can do the same, for instance, the following code will return the value and metadata of the NewValue nested in MaxSpeed:

// Get the value of the MaxSpeed, which is a inner TwinCollection.
    TwinCollection innerMaxSpeed = (TwinCollection) twinCollection.getJob("MaxSpeed");
    
    // From the inner TwinCollection, get the value of the NewValue.
    Long maxSpeedNewValue = innerMaxSpeed.getJob("NewValue");
    
    // As in the root TwinCollection, the inner TwinCollection contain its own metadata.
    // So, get the metadata information for the inner NewValue.
    TwinMetadata maxSpeedNewValueMetadata = innerMaxSpeed.getTwinMetadata("NewValue");
    Date newValueLastUpdated = maxSpeedNewValueMetadata.getLastUpdated(); //Shall contain `2017-09-21T02:07:44.238Z`
    Integer newValueLastUpdatedVersion = maxSpeedNewValueMetadata.getLastUpdatedVersion(); //Shall contain `4`
    

Constructor Summary

Constructor	Description
TwinCollection()	Constructor Creates an empty collection. Fill it with put(String key, Object value) or putAll(Map).
TwinCollection(Map<? extends String, Object> map)	Constructor Creates a new Twin collection coping the provided Map.
TwinCollection(TwinCollection collection)	Constructor Creates a new Twin collection coping the provided collection.

Method Summary

Modifier and Type	Method and Description
final TwinMetadata	getTwinMetadata() Getter for the TwinCollection metadata
final TwinMetadata	getTwinMetadata(String key) Getter for the entry metadata in the TwinCollection.
final Integer	getVersion() Getter for the version.
Object	put(String key, Object value) Add a single new entry in the TwinCollection. OverrideHashMap.put(String, Object)  </code> .</p> This function will add a single pair key value to the TwinCollection. By the Twin definition, theObject  </code> can contain types of<code>Boolean  </code> , <code>Number  </code> ,<code>String  </code> ,<code>Object  </code> , or up to 5 levels of sub-TwinCollection, but it cannot be types defined by the user or arrays.</p>
void	putAll(Map<? extends String, ?> map) Add all information in the provided Map to the TwinCollection. OverrideHashMap.putAll(Map)  </code> .</p> This function will add all entries in the Map to the TwinCollection. If the provided key already exists, it will replace the value by the new one. This function will not delete or change the content of the other keys in the Map. As defined by the Twin, the value of a entry can be an inner Map. TwinCollection will accept up to 5 levels of inner Maps.
final void	setVersion(Integer version) Setter for the version of this twin collection.
JsonObject	toJsonObject() Serializer Creates aJsonElement  </code> , which the content represents the information in this class and its subclasses in a JSON format.</p> This is useful if the caller will integrate this JSON with JSON from other classes to generate a consolidated JSON.
String	toString() Creates a pretty print JSON with the content of this class and subclasses.

Constructor Details

TwinCollection

public TwinCollection()

Constructor

Creates an empty collection. Fill it with put(String key, Object value) or putAll(Map).

TwinCollection

public TwinCollection(Map map)

Constructor

Creates a new Twin collection coping the provided Map.

Parameters:

map -

the Map of? extends String 

</code> and<code>Object 

</code> with the Twin collection </p>

TwinCollection

public TwinCollection(TwinCollection collection)

Constructor

Creates a new Twin collection coping the provided collection.

Parameters:

collection -

the Collection of? extends String 

</code> and<code>Object 

</code> with the Twin collection </p>

Method Details

getTwinMetadata

public final TwinMetadata getTwinMetadata()

Getter for the TwinCollection metadata

Returns:

the TwinMetadata of the Whole TwinCollection. It can benull 

</code> . </p>

getTwinMetadata

public final TwinMetadata getTwinMetadata(String key)

Getter for the entry metadata in the TwinCollection.

Parameters:

key -

theString 

</code> with the name of the entry to retrieve the metadata. </p>

Returns:

the TwinMetadata ot the specific entry in the TwinCollection. It can benull 

</code> . </p>

getVersion

public final Integer getVersion()

Getter for the version.

Returns:

TheInteger 

</code> with the version content. It can be<code>null 

</code> . </p>

put

public Object put(String key, Object value)

Add a single new entry in the TwinCollection.

OverrideHashMap.put(String, Object) 

</code> .</p>

This function will add a single pair key value to the TwinCollection. By the Twin definition, theObject 

</code> can contain types of<code>Boolean 

</code> , <code>Number 

</code> ,<code>String 

</code> ,<code>Object 

</code> , or up to 5 levels of sub-TwinCollection, but it cannot be types defined by the user or arrays.</p>

Parameters:

key -

theString 

</code> that represents the key of the new entry. It cannot be<code>null 

</code> or empty. </p>

value -

theObject 

</code> that represents the value of the new entry. It cannot be user defined type or array. </p>

Returns:

TheObject 

</code> that correspond to the last value of this key. It will be<code>null 

</code> if there is no previous value. </p>

putAll

public void putAll(Map map)

Add all information in the provided Map to the TwinCollection.

OverrideHashMap.putAll(Map) 

</code> .</p>

This function will add all entries in the Map to the TwinCollection. If the provided key already exists, it will replace the value by the new one. This function will not delete or change the content of the other keys in the Map.

As defined by the Twin, the value of a entry can be an inner Map. TwinCollection will accept up to 5 levels of inner Maps.

Parameters:

map -

AMap 

</code> of entries to add to the TwinCollection. </p>

setVersion

public final void setVersion(Integer version)

Setter for the version of this twin collection.

Parameters:

version - the version.

toJsonObject

public JsonObject toJsonObject()

Serializer

Creates aJsonElement 

</code> , which the content represents the information in this class and its subclasses in a JSON format.</p>

This is useful if the caller will integrate this JSON with JSON from other classes to generate a consolidated JSON.

Returns:

TheJsonElement 

</code> with the content of this class. </p>

toString

public String toString()

Creates a pretty print JSON with the content of this class and subclasses.

Returns:

TheString 

</code> with the pretty print JSON. </p>