RuntimeException - ConnectException - Connection refused

[ChaiBapchya]

Following the steps mentioned on - http://ampcamp.berkeley.edu/3/exercises/realtime-processing-with-spark-streaming.html
For Java

Edited the Tutorial.java file along with twitter.txt (setting the corresponding credentials)
However while running the command -

sbt/sbt package run

Following error -

: Retrying connect to server: ip-172-31-22-114.ec2.internal/172.31.22.114:9000. Already tried 9 time(s).
[error] (run-main) java.net.ConnectException: Call to ip-172-31-22-114.ec2.internal/172.31.22.114:9000 failed on connection exception: java.net.ConnectException: Connection refused
java.net.ConnectException: Call to ip-172-31-22-114.ec2.internal/172.31.22.114:9000 failed on connection exception: java.net.ConnectException: Connection refused
    at org.apache.hadoop.ipc.Client.wrapException(Client.java:1099)
    at org.apache.hadoop.ipc.Client.call(Client.java:1075)
    at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
    at com.sun.proxy.$Proxy3.getProtocolVersion(Unknown Source)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:396)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:379)
    at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:119)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:238)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:203)
    at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:89)
    at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1386)
    at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:66)
    at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1404)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:254)
    at org.apache.hadoop.fs.Path.getFileSystem(Path.java:187)
    at spark.SparkContext.setCheckpointDir(SparkContext.scala:829)
    at spark.streaming.StreamingContext.checkpoint(StreamingContext.scala:171)
    at spark.streaming.api.java.JavaStreamingContext.checkpoint(JavaStreamingContext.scala:589)
    at Tutorial.main(Tutorial.java:41)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
Caused by: java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:744)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:489)
    at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:434)
    at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:560)
    at org.apache.hadoop.ipc.Client$Connection.access$2000(Client.java:184)
    at org.apache.hadoop.ipc.Client.getConnection(Client.java:1206)
    at org.apache.hadoop.ipc.Client.call(Client.java:1050)
    at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
    at com.sun.proxy.$Proxy3.getProtocolVersion(Unknown Source)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:396)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:379)
    at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:119)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:238)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:203)
    at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:89)
    at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1386)
    at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:66)
    at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1404)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:254)
    at org.apache.hadoop.fs.Path.getFileSystem(Path.java:187)
    at spark.SparkContext.setCheckpointDir(SparkContext.scala:829)
    at spark.streaming.StreamingContext.checkpoint(StreamingContext.scala:171)
    at spark.streaming.api.java.JavaStreamingContext.checkpoint(JavaStreamingContext.scala:589)
    at Tutorial.main(Tutorial.java:41)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
java.lang.RuntimeException: Nonzero exit code: 1
    at scala.sys.package$.error(package.scala:27)

[ChaiBapchya]

Error is at line 41 of Tutorial.java

ssc.checkpoint(checkpointDir);

When I print checkpointDir which is called from ScalaHelper.java, It gives

hdfs://ip-172-31-22-116.ec2.internal:9000/checkpoint/