XLS_Reader java file

Exception occur while running Reading_Writing_XLS.java even i specified right path of the file

at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at Xls_Reader.<init>(Xls_Reader.java:33)
at Reading_Writing_XLS.main(Reading_Writing_XLS.java:9)
Exception in thread "main" java.lang.NullPointerException
at Xls_Reader.getRowCount(Xls_Reader.java:45)
at Reading_Writing_XLS.main(Reading_Writing_XLS.java:10)
ERROR: JDWP Unable to get JNI 1.2 environment, jvm->GetEnv() return code = -2
JDWP exit error AGENT_ERROR_NO_JNI_ENV(183): [util.c:840]