Added examples on Tuple,PairRDD

src/main/java/com/virtualpairprogrammers/Main.java

 package com.virtualpairprogrammers;
 
+import lombok.extern.slf4j.Slf4j;
 import org.apache.log4j.Level;
 import org.apache.log4j.Logger;
 import org.apache.spark.SparkConf;
 import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
+import scala.Tuple2;
 
 import java.util.ArrayList;
 import java.util.List;
 
+@Slf4j
 public class Main {
     public static void main(String[] args) {
-        List<Double> inputData=new ArrayList<>();
-        inputData.add(55.5);
-        inputData.add(43.2);
-        inputData.add(23.21);
-        inputData.add(67.2);
+        List<Integer> inputData=new ArrayList<>();
+        inputData.add(55);
+        inputData.add(43);
+        inputData.add(23);
+        inputData.add(67);
 
         //to avoid unnecessary INFO logs and have WARN log only
         Logger.getLogger("org.apache").setLevel(Level.WARN);
@@ -24,11 +27,37 @@ public class Main {
         SparkConf conf=new SparkConf().setAppName("startingSpark")
                 .setMaster("local[*]");
 
-        //represents spark cluster connection
+        //represents a connection with spark cluster
         JavaSparkContext sc=new JavaSparkContext(conf);
 
-        //to load java data into rdd
-       JavaRDD<Double> myRDD= sc.parallelize(inputData);
+        //to load java data into rdd(spark)
+       JavaRDD<Integer> myRDD= sc.parallelize(inputData);
+
+       //reduce method to perform operations on rdd
+       Integer result= myRDD.reduce((value1,value2)-> value1+value2 );
+       log.info(" Result: "+result);
+
+       //map method to perform operations on rdd
+       JavaRDD<Double> sqrtRDD= myRDD.map(value-> Math.sqrt(value));
+       sqrtRDD.foreach(res-> log.info("Result :"+res));
+
+       //how many elements in sqrtRDD
+        long count=sqrtRDD.count();
+        log.info("Elements in rdd: "+count);
+
+        //how many elements in sqrtRDD
+        //using map and reduce
+        JavaRDD<Long> singleRdd=sqrtRDD.map(value-> 1L);
+        Long count1=singleRdd.reduce((value1,value2)-> value1+value2);
+        log.info("Elements in rdd :"+count1);
+
+        // to avoid notserializable exception
+        sqrtRDD.collect().forEach(System.out::println);
+
+        //tuples in spark
+       JavaRDD<Tuple2<Integer,Double>> newSqrtRdd= myRDD.map(value-> new Tuple2(value,Math.sqrt(value)));
+       newSqrtRdd.collect().forEach(System.out::println);
+
 
        //close the spark connection
         sc.close();

src/main/java/com/virtualpairprogrammers/Main1.java

+package com.virtualpairprogrammers;
+
+import org.apache.log4j.Level;
+import org.apache.log4j.Logger;
+import org.apache.spark.SparkConf;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Main1 {
+    public static void main(String[] args) {
+        List<String> inputData = new ArrayList<>();
+        inputData.add("WARN: Tuesday 4 September 0405");
+        inputData.add("ERROR: Tuesday 4 September 0408");
+        inputData.add("FATAL: Wednesday 5 September 1632");
+        inputData.add("ERROR: Friday 7 September 1854");
+        inputData.add("WARN: Saturday 8 September 1942");
+
+        Logger.getLogger("org.apache").setLevel(Level.WARN);
+
+        SparkConf conf = new SparkConf().setAppName("startingSpark").setMaster("local[*]");
+        JavaSparkContext sc = new JavaSparkContext(conf);
+
+        JavaRDD<String> originaLogMessages=sc.parallelize(inputData);
+
+        //pairRDD is similier to Map collection except it can store duplicate keys
+    }
+}