How to get the current filename in Hadoop Reduce

I am using the WordCount example and in the Reduce function, I need to get the file name.

public static class Reduce extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable> {
  public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
    int sum = 0;
    while (values.hasNext()) {
      sum += values.next().get();
    }
    String filename = ((FileSplit)(.getContext()).getInputSplit()).getPath().getName();
    // ----------------------------^ I need to get the context and filename!
    key.set(key.toString() + " (" + filename + ")");
    output.collect(key, new IntWritable(sum));
  }
}

This is the above modified code currently, where I wanna get the filename to be printed for the word. I tried following Java Hadoop: How can I create mappers that take as input files and give an output which is the number of lines in each file? but I couldn't get the context object.

I am new to hadoop and need this help. Any help guys?