hadoop - Context Object in JAVA MapReduce -

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this question has answer here:

what use of context context in map() method.

public void map(longwritable key, text value, context context)

extracted here

in:

map(object key, object value, context context)

to allow serialization , transfer of types of data, java defines own writable class. these box classes text (for string), intwritable (for integers), longwritable (for long) instances of base class writable (for values), , instances of writablecomparable (for keys). context used collect , write ouput intermediate final files.


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