PYspark SparkContext Error "error occurred while calling None.org.apache.spark.api.java.JavaSparkContext."

Question

I know this question has been posted before, but I tried implementing the solutions, but none worked for me. I installed Spark for Jupyter Notebook using this tutorial:

https://medium.com/@GalarnykMichael/install-spark-on-mac-pyspark-
453f395f240b#.be80dcqat

Installed Latest Version of Apache Spark on the MAC

When I try to run the following code in Jupyter

wordcounts = sc.textFile('words.txt')

I get the following error:

name 'sc' is not defined

When I try adding the Code:

from pyspark import SparkContext, SparkConf
sc =SparkContext()

getting the following error:

An error occurred while calling 
None.org.apache.spark.api.java.JavaSparkContext.
: java.lang.NoClassDefFoundError: Could not initialize class 
org.apache.hadoop.util.StringUtils
at
org.apache.hadoop.security.SecurityUtil.
getAuthenticationMethod(SecurityUtil.java:611)

Added the path in bash:

export SPARK_PATH=~/spark-2.2.1-bin-hadoop2.7
export PYSPARK_DRIVER_PYTHON="jupyter"
export PYSPARK_DRIVER_PYTHON_OPTS="notebook"

#For python 3, You have to add the line below or you will get an error
# export PYSPARK_PYTHON=python3
alias snotebook='$SPARK_PATH/bin/pyspark --master local[2]'

Please help me resolve this.