org.apache.flink.table.api.dataview

Class ListView<T>

java.lang.Object

org.apache.flink.table.api.dataview.ListView<T>

All Implemented Interfaces:

Serializable, DataView

@TypeInfo(value=ListViewTypeInfoFactory.class)
 @PublicEvolving
public class ListView<T>
extends Object
implements DataView

A ListView provides List functionality for accumulators used by user-defined aggregate functions AggregateFunction.

A ListView can be backed by a Java ArrayList or a state backend, depending on the context in which the aggregate function is used.

At runtime ListView will be replaced by a state ListView which is backed by a ListState instead of ArrayList if it works in streaming.

Example of an accumulator type with a ListView and an aggregate function that uses it:

  public class MyAccum {
    public ListView list;
    public long count;
  }

  public class MyAgg extends AggregateFunction {

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
org.apache.flink.api.common.typeinfo.TypeInformation<?>	elementType
List<T>	list

Constructor Summary

Constructors

Constructor and Description
ListView() Creates a list view.
ListView(org.apache.flink.api.common.typeinfo.TypeInformation<?> elementType) Creates a list view for elements of the specified type.
ListView(org.apache.flink.api.common.typeinfo.TypeInformation<?> elementType, List<T> list)

Method Summary

Modifier and Type	Method and Description
void	add(T value) Adds the given value to the list.
void	addAll(List<T> list) Adds all of the elements of the specified list to this list view.
void	clear() Removes all of the elements from this list view.
boolean	equals(Object o)
Iterable<T>	get() Returns an iterable of the list view.
int	hashCode()
boolean	remove(T value) Removes the given value from the list.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

elementType

public transient org.apache.flink.api.common.typeinfo.TypeInformation<?> elementType

list

public final List<T> list

Constructor Detail

ListView

public ListView(org.apache.flink.api.common.typeinfo.TypeInformation<?> elementType,
                List<T> list)

ListView

public ListView(org.apache.flink.api.common.typeinfo.TypeInformation<?> elementType)

Creates a list view for elements of the specified type.

Parameters:

elementType - The type of the list view elements.

ListView

public ListView()

Creates a list view.

Method Detail

get

public Iterable<T> get()
                throws Exception

Returns an iterable of the list view.

Returns:

The iterable of the list.

Throws:

Exception - Thrown if the system cannot get data.

add

public void add(T value)
         throws Exception

Adds the given value to the list.

Parameters:

value - The element to be appended to this list view.

Throws:

Exception - Thrown if the system cannot add data.

addAll

public void addAll(List<T> list)
            throws Exception

Adds all of the elements of the specified list to this list view.

Parameters:

list - The list with the elements that will be stored in this list view.

Throws:

Exception - Thrown if the system cannot add all data.

remove

public boolean remove(T value)
               throws Exception

Removes the given value from the list.

Parameters:

value - The element to be removed from this list view.

Throws:

Exception

clear

public void clear()

Removes all of the elements from this list view.

Specified by:

clear in interface DataView

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object