Why does the following happen and how can I fix it?
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/lang/Validate
at org.jsoup.DataUtil.load(DataUtil.java:47)
at org.jsoup.Jsoup.parse(Jsoup.java:57)
at linksfind.main(linksfind.java:12)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.Validate
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 3 more