As underscore(_) is not allowed. It may be the problem if your other configuration are ok.
Your configuration file should be something like
<property>
<name>fs.default.name</name>
<value>hdfs://masterServer:9000/</value>
</property>
http://*.com/questions/27956973/java-io-ioexception-incomplete-hdfs-uri-no-host
所有文档在，
https://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/
下找。