How to write the spark programming to count letters

public class WordCount {


static class SplitFunction implements FlatMapFunction<String, String>
 {
 public Iterable<String> call(String s) {
    return Arrays.asList(s.split(" "));
  }
 }

public static void main(String[] args)
{

SparkConf sparkConf = new SparkConf();
sparkConf.setAppName("Spark WordCount example using Java");

sparkConf.setMaster("local");
JavaSparkContext sparkContext = new JavaSparkContext(sparkConf);

JavaRDD<String> textFile = sparkContext.textFile("input.txt");

JavaRDD<String> words = textFile.flatMap(new SplitFunction());

JavaPairRDD<String, Integer> pairs = words.mapToPair(new PairFunction<String, String, Integer>() {
      public Tuple2<String, Integer> call(String s) {
        return new Tuple2<String, Integer>(s, 1);
      }
     });
 JavaPairRDD<String, Integer> counts = pairs.reduceByKey(
    new Function2<Integer, Integer, Integer>() {
      public Integer call(Integer a, Integer b) {
        return a + b;
      }
    });


counts.saveAsTextFile("output");
sparkContext.stop();
sparkContext.close();
   }
 }