Unable to correct NMONVisualizer java error. Can someone help to decode this java error?

Hello AIX and Java gurus,
I have a java error that I have no clue how to resolve. I am trying to run the popular NMONVisualizer utility against a NMON dataset and getting the error as shown below:

/db2storage/NMON >java -jar NMONVisualizer_2015-02-02.jar com.ibm.nmon.ReportGenerator rasmq02hdqra_150404_1027.nmon

Exception in thread "main" java.lang.NoSuchMethodError: java.net.URLDecoder: method decode(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String; not found
        at org.eclipse.jdt.internal.jarinjarloader.RsrcURLConnection.getInputStream(RsrcURLConnection.java:42)
        at java.net.URL.openStream(URL.java:827)
        at sun.misc.URLClassPath$Loader.getResource(URLClassPath.java:449)
        at sun.misc.URLClassPath.getResource(URLClassPath.java:166)
        at java.net.URLClassLoader$ClassFinder.run(URLClassLoader.java:676)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:239)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:516)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:448)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:220)
        at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:54)

How ca I resolve this error? Immediate help needed.
Thanks
okonita

check your classpath