title: Error in RWeka in R package
body: <p>I have searched SO and everywhere else and nothing works to fix the unsupported major.minor version 51 error. I uninstalled Java 8 and installed Java 7. No luck.
  Thank you for your help.
  I am using:
   R 3.3.1
  Java 8.91
  OSX, el capitan
  library(NLP)
  library(tm)
  library(RWeka)
  library(rJava)
  library((RWekajars))
  library(parallel)
  options(mc.cores=1)
  Here is the R code causing the error:</p>
  
  <pre><code>trigram &lt;- function(x){NGramTokenizer(x,control=Weka_control(min=3,max=3))}
  tdm &lt;- TermDocumentMatrix(corpus2,control=list(tokenize=trigram))
  
  Here is the error I get.
   Error in .jnew(name) : 
    java.lang.UnsupportedClassVersionError: weka/core/tokenizers/NGramTokenizer : Unsupported major.minor version 51.0 
  9 stop(structure(list(message = "java.lang.UnsupportedClassVersionError: weka/core/tokenizers/NGramTokenizer : Unsupported major.minor version 51.0", 
      call = .jnew(name), jobj = &lt;S4 object of class structure("jobjRef", package = "rJava")&gt;), .Names = c("message", 
  "call", "jobj"), class = c("UnsupportedClassVersionError", "ClassFormatError", 
  "LinkageError", "Error", "Throwable", "Object", "Exception",  ... 
  8 .jnew(name) 
  7 NGramTokenizer(x, control = Weka_control(min = 3, max = 3)) 
  6 .tokenize(doc) 
  5 FUN(X[[i]], ...) 
  4 lapply(X = X, FUN = FUN, ...) 
  3 mclapply(unname(content(x)), termFreq, control) 
  2 TermDocumentMatrix.VCorpus(corpus2, control = list(tokenize = trigram)) 
  1 TermDocumentMatrix(corpus2, control = list(tokenize = trigram)) 
  </code></pre>