public class EmptyRowDataKeySelector extends Object implements RowDataKeySelector
Modifier and Type | Field and Description |
---|---|
static EmptyRowDataKeySelector |
INSTANCE |
Constructor and Description |
---|
EmptyRowDataKeySelector() |
Modifier and Type | Method and Description |
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RowData |
getKey(RowData value)
User-defined function that deterministically extracts the key from an object.
|
RowDataTypeInfo |
getProducedType()
Gets the data type (as a
TypeInformation ) produced by this function or input format. |
public static final EmptyRowDataKeySelector INSTANCE
public RowData getKey(RowData value) throws Exception
KeySelector
For example for a class:
public class Word { String word; int count; }
The key extractor could return the word as a key to group all Word objects by the String they contain.
The code would look like this
public String getKey(Word w) { return w.word; }
getKey
in interface KeySelector<RowData,RowData>
value
- The object to get the key from.Exception
- Throwing an exception will cause the execution of the respective task to
fail, and trigger recovery or cancellation of the program.public RowDataTypeInfo getProducedType()
ResultTypeQueryable
TypeInformation
) produced by this function or input format.getProducedType
in interface ResultTypeQueryable<RowData>
getProducedType
in interface RowDataKeySelector
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