Package org.apache.flink.api.java.functions

Class NullByteKeySelector<T>

  • Type Parameters:
    T - The type of the input element.
    All Implemented Interfaces:
    Serializable, Function, KeySelector<T,​Byte>
    @Internal
public class NullByteKeySelector<T>
extends Object
implements KeySelector<T,​Byte>
    Used as a dummy KeySelector to allow using keyed operators for non-keyed use cases. Essentially, it gives all incoming records the same key, which is a (byte) 0 value.
    See Also:
    Serialized Form

    • Constructor Detail

      • NullByteKeySelector

        public NullByteKeySelector()

    • Method Detail

      • getKey

        public Byte getKey​(T value)
            throws Exception
        Description copied from interface: KeySelector
        User-defined function that deterministically extracts the key from an object.

        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;
        }
        Specified by:
        getKey in interface KeySelector<T,​Byte>
        Parameters:
        value - The object to get the key from.
        Returns:
        The extracted key.
        Throws:
        Exception - Throwing an exception will cause the execution of the respective task to fail, and trigger recovery or cancellation of the program.