How can we pass List<Text> as Mapper output?

Question

I am working on a problem of Map-Reduce. But I stuck at one point that how can I pass List<Text> as Mapper output? Is it possible or not? If yes, then how can we tell the configuration about the Mapper output class?

Answer 1

You may use the ArrayWritable class as value object from your mapper class. Please refer the below code snippet for your mapper class,

ArrayWritable arrayWritable = new ArrayWritable(Text.class);

Text [] textValues = new Text[2];
textValues[0] = new Text("value1");
textValues[1] = new Text("value1");

arrayWritable.set(textValues );
context.write(key , arrayWritable );

set the value class as following in your driver class,

job.setMapOutputValueClass(ArrayWritable.class);