MapData (Flink : Table : Common 2.1.0 API)

All Known Implementing Classes:

BinaryMapData, ColumnarMapData, GenericMapData
```
@PublicEvolving
public interface MapData
```
Base interface of an internal data structure representing data of MapType or MultisetType.
Note: All keys and values of this data structure must be internal data structures. All keys must be of the same type; same for values. See RowData for more information about internal data structures.
Use GenericMapData to construct instances of this interface from regular Java maps.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`ArrayData`	`keyArray()`	Returns an array view of the keys contained in this map.
`int`	`size()`	Returns the number of key-value mappings in this map.
`ArrayData`	`valueArray()`	Returns an array view of the values contained in this map.

- Method Detail
  - size
```
int size()
```
    Returns the number of key-value mappings in this map.
  - keyArray
```
ArrayData keyArray()
```
    Returns an array view of the keys contained in this map.
    A key-value pair has the same index in the key array and value array.
  - valueArray
```
ArrayData valueArray()
```
    Returns an array view of the values contained in this map.
    A key-value pair has the same index in the key array and value array.