@Override public boolean next(ImmutableBytesWritable rowKey, ResultWritable value) throws IOException {

        boolean next = false;

        try {
          next = recordReader.nextKeyValue();

          if (next) {
            rowKey.set(recordReader.getCurrentValue().getRow());
            value.setResult(recordReader.getCurrentValue());
          }
        } catch (InterruptedException e) {
          throw new IOException(e);
        }

        return next;
      }
HiveHBaseTableInputFormat implements InputFormat for HBase storage handler
tables, decorating an underlying HBase TableInputFormat with extra Hive logic
such as column pruning and filter pushdown.
hbase-handler/src/java/org/apache/hadoop/hive/hbase/HiveHBaseTableInputFormat.java