Java WordCount on Spark using Dataset

WordCount.java

//tested on spark 2.0

import org.apache.spark.sql.*;
import java.util.Arrays;

public class WordCount {
	
	public static void main(String[] args) {
    if (args.length < 2) {
      System.err.println("Please provide the full path of input file and output dir as arguments");
      System.exit(0);
    }

    
    SparkSession spark = SparkSession
    		  .builder()
    		  .master("local")
    		  .appName("WordCount")
    		  .getOrCreate();
    
    
    Dataset<String> df = spark.read().text(args[0]).as(Encoders.STRING());
    Dataset<String> words = df.flatMap(s -> {
    								return  Arrays.asList(s.toLowerCase().split(" ")).iterator(); 
    							}, Encoders.STRING())
    							.filter(s -> !s.isEmpty())
    							.coalesce(1); //one partition (parallelism level)
    //words.printSchema();   // { value: string (nullable = true) }
    Dataset<Row> t = words.groupBy("value") //<k, iter(V)>
    		.count()
    		.toDF("word","count");
    t = t.sort(functions.desc("count"));
    t.toJavaRDD().saveAsTextFile(args[1]);
  }
}