How to use map function in SPARK with Java

Question

I am trying to read a csv file in a lawsuit and I want to split comma separated lines so that I have an RDD with a two dimensional array. I am very new to Spark.

I tried to do this:

public class SimpleApp 
{   
    public static void main(String[] args) throws Exception 
    {       
        String master = "local[2]";
        String csvInput = "/home/userName/Downloads/countrylist.csv";
        String csvOutput = "/home/userName/Downloads/countrylist";

        JavaSparkContext sc = new JavaSparkContext(master, "loadwholecsv", System.getenv("SPARK_HOME"), System.getenv("JARS"));

        JavaRDD<String> csvData = sc.textFile(csvInput, 1);
        JavaRDD<String> words = csvData.map(new Function <List<String>>() { //line 43
              @Override
              public List<String> call(String s) {
                return Arrays.asList(s.split("\\s*,\\s*"));
              }
            });

        words.saveAsTextFile(csvOutput);
    }
}

This should split the lines and return an ArrayList. But I'm not so sure about that. I get this error:

SimpleApp.java:[43,58] wrong number of type arguments; required 2

Answer 1

, . -, , , flatMap, , RDD , RDD , flatMap . - , . JavaRDD... :

JavaRDD<String> words = rdd.flatMap(
  new FlatMapFunction<String, String>() { public Iterable<String> call(String s) {
      return Arrays.asList(s.split("\\s*,\\s*"));
    }});

Answer 2

, ...

        //======Using flatMap(RDD of words)==============
       JavaRDD<String> csvData = spark.textFile(GlobalConstants.STR_INPUT_FILE_PATH, 1);
        JavaRDD<String> counts = csvData.flatMap(new FlatMapFunction<String, String>() {
          //line 43
              @Override
              public Iterable<String> call(String s) {
                return Arrays.asList(s.split("\\s*,\\s*"));
              }
            });     

    //======Using map(RDD of Lists of words)==============
        JavaRDD<String> csvData = spark.textFile(GlobalConstants.STR_INPUT_FILE_PATH, 1);
        JavaRDD<List<String>> counts = csvData.map(new Function <String, List<String>>() { //line 43
              @Override
              public List<String> call(String s) {
                return Arrays.asList(s.split("\\s*,\\s*"));
              }
            }); 

    //=====================================

    counts.saveAsTextFile(GlobalConstants.STR_OUTPUT_FILE_PATH);