Instances of this class encapsulate the data and priority at a location. It is used in
transactions, and it is intended to be inspected and then updated to the desired data at that
location.
Note that changes made to a child MutableData instance will be visible to the parent and vice
versa.
Public Method Summary
MutableData | |
boolean | |
Iterable<MutableData> |
getChildren()
Used to iterate over the immediate children at this location
|
long | |
String |
getKey()
|
Object |
getPriority()
Gets the current priority at this location.
|
<T> T |
getValue(GenericTypeIndicator<T>
t)
Due to the way that Java implements generics, it takes an extra step to get
back a properly-typed Collection.
|
Object |
getValue()
getValue() returns the data contained in this instance as native types.
|
<T> T | |
boolean | |
boolean | |
void | |
void | |
String |
toString()
|
Inherited Method Summary
Public Methods
public MutableData child (String path)
Used to obtain a MutableData instance that encapsulates the data and priority at the given relative path.
Parameters
path | A relative path |
---|
Returns
- An instance encapsulating the data and priority at the given path
public boolean equals (Object o)
public Iterable<MutableData> getChildren ()
Used to iterate over the immediate children at this location
for (MutableData child : parent.getChildren()) {
...
}
Returns
- The immediate children at this location
public long getChildrenCount ()
Returns
- The number of immediate children at this location
public String getKey ()
Returns
- The key name of this location, or null if it is the top-most location
public Object getPriority ()
Gets the current priority at this location. The possible return types are:
- Double
- String
Returns
- The priority at this location as a native type or null if no priority was set
public T getValue (GenericTypeIndicator<T> t)
Due to the way that Java implements generics, it takes an extra step to get back a
properly-typed Collection. So, in the case where you want a List
of Message
instances, you will need to do something like the following:
GenericTypeIndicator<List<Message>> t =
new GenericTypeIndicator<List<Message>>() {};
List<Message> messages = mutableData.getValue(t);
It is important to use a subclass of GenericTypeIndicator
.
See
GenericTypeIndicator
for more details
Parameters
t | A subclass of GenericTypeIndicator
indicating the type of generic collection to be returned. |
---|
Returns
- A properly typed collection, populated with the data from this instance, or null if there is no data at this location.
public Object getValue ()
getValue() returns the data contained in this instance as native types. The possible types returned are:
- Boolean
- String
- Long
- Double
- Map<String, Object>
- List<Object>
Object
in the
above list is given by the same list. These types correspond to the types available in
JSON.
Returns
- The data contained in this instance as native types, or null if there is no data at this location.
public T getValue (Class<T> valueType)
This method is used to marshall the data contained in this instance into a class of your choosing. The class must fit 2 simple constraints:
- The class must have a default constructor that takes no arguments
- The class must define public getters for the properties to be assigned. Properties without a public getter will be set to their default value when an instance is deserialized
class Message {
private String author;
private String text;
private Message() {}
public Message(String author, String text) {
this.author = author;
this.text = text;
}
public String getAuthor() {
return author;
}
public String getText() {
return text;
}
}
// Later
Message m = mutableData.getValue(Message.class);
Parameters
valueType | The class into which this data in this instance should be marshalled |
---|
Returns
- An instance of the class passed in, populated with the data from this instance, or null if there is no data at this location.
public boolean hasChild (String path)
Parameters
path | A relative path |
---|
Returns
- True if data exists at the given path, otherwise false
public boolean hasChildren ()
Returns
- True if the data at this location has children, false otherwise
public void setPriority (Object priority)
Sets the priority at this location
Parameters
priority | The desired priority or null to clear the existing priority |
---|
public void setValue (Object value)
Set the data at this location to the given value. The native types accepted by this method for the value correspond to the JSON types:
- Boolean
- Long
- Double
- Map<String, Object>
- List<Object>
In addition, you can set instances of your own class into this location, provided they satisfy the following constraints:
- The class must have a default constructor that takes no arguments
- The class must define public getters for the properties to be assigned. Properties without a public getter will be set to their default value when an instance is deserialized
Generic collections of objects that satisfy the above constraints are also permitted, i.e.
Map<String, MyPOJO>
, as well as null values.
Note that this overrides the priority, which must be set separately.
Parameters
value | The value to set at this location or null to delete the existing data |
---|
Throws
DatabaseException |
---|