mapreduce - Why can't output value of hadoop map be null? -


i want use hadoop mapreduce sort lines of log. put fields of line output key, , set output value null. when run, null pointer exception raised @ line

context.write(new text(outkeystr), null);

so why can't output value of hadoop map null? why output value of hadoop reduce can (i tested)?

you can't use explict value null can use nullwritable class if don't care value


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