October 25, 2021 - Sarkari Job Alert

I am trying to start with Spark. I have Hadoop (3.3.1) and Spark (3.2.2) in my library. I have set the SPARK_HOME, PATH, HADOOP_HOME and LD_LIBRARY_PATH to their respective paths. I am also running JDK 17 (echo and -version work fine in the terminal).

Yet, I still get the following error:

Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
21/10/25 17:17:07 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
java.lang.IllegalAccessError: class org.apache.spark.storage.StorageUtils$ (in unnamed module @0x1f508f09) cannot access class sun.nio.ch.DirectBuffer (in module java.base) because module java.base does not export sun.nio.ch to unnamed module @0x1f508f09
  at org.apache.spark.storage.StorageUtils$.<init>(StorageUtils.scala:213)
  at org.apache.spark.storage.StorageUtils$.<clinit>(StorageUtils.scala)
  at org.apache.spark.storage.BlockManagerMasterEndpoint.<init>(BlockManagerMasterEndpoint.scala:110)
  at org.apache.spark.SparkEnv$.$anonfun$create$9(SparkEnv.scala:348)
  at org.apache.spark.SparkEnv$.registerOrLookupEndpoint$1(SparkEnv.scala:287)
  at org.apache.spark.SparkEnv$.create(SparkEnv.scala:336)
  at org.apache.spark.SparkEnv$.createDriverEnv(SparkEnv.scala:191)
  at org.apache.spark.SparkContext.createSparkEnv(SparkContext.scala:277)
  at org.apache.spark.SparkContext.<init>(SparkContext.scala:460)
  at org.apache.spark.SparkContext$.getOrCreate(SparkContext.scala:2690)
  at org.apache.spark.sql.SparkSession$Builder.$anonfun$getOrCreate$2(SparkSession.scala:949)
  at scala.Option.getOrElse(Option.scala:189)
  at org.apache.spark.sql.SparkSession$Builder.getOrCreate(SparkSession.scala:943)
  at org.apache.spark.repl.Main$.createSparkSession(Main.scala:106)
  ... 55 elided
<console>:14: error: not found: value spark
       import spark.implicits._
              ^
<console>:14: error: not found: value spark
       import spark.sql
              ^
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _ / _ / _ `/ __/  '_/
   /___/ .__/_,_/_/ /_/_   version 3.2.0
      /_/
         
Using Scala version 2.12.15 (OpenJDK 64-Bit Server VM, Java 17.0.1)
Type in expressions to have them evaluated.
Type :help for more information.

Any ideas how to fix this?

Answer

Java 17 isn’t supported – Spark runs on Java 8/11 (source: https://spark.apache.org/docs/latest/).

So install Java 11 and point Spark to that.

The warning unable to load native-hadoop library for platform is quite common and doesn’t mean that anything’s wrong.

Answer

This may help you:-

Method to write to a csv file.

public static void exportToCSV(JTable table,
        String path) {

    try {

        TableModel model = table.getModel();
        FileWriter csv = new FileWriter(new File(path));

        for (int i = 0; i < model.getColumnCount(); i++) {
            csv.write(model.getColumnName(i) + ",");
        }

        csv.write("n");

        for (int i = 0; i < model.getRowCount(); i++) {
            for (int j = 0; j < model.getColumnCount(); j++) {
                csv.write(model.getValueAt(i, j).toString() + ",");
            }
            csv.write("n");
        }

        csv.close();
    } catch (IOException e) {
       System.out.println("Error "+e);
    }
}

For reading and showing it to a JTable you can use OpenCSV.

CSVReader reader = new CSVReader(new FileReader("file.csv")); 
List list = reader.readAll();
JTable table = new JTable(list.toArray());

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