title: R: Shiny, how to use renderTable to replace reactiveTable?
body: <p>I am trying to load multiple text files (each has a string of characters) into Shiny and I found a very nice tutorial to begin with: 
  <a href="https://gist.github.com/jcheng5/4050398" rel="nofollow">https://gist.github.com/jcheng5/4050398</a>
  The code is shown below:</p>
  
  <h3>ui.R</h3>
  
  <p><code>shinyUI(pageWithSidebar(
      headerPanel("File input test"),
      sidebarPanel(
          fileInput("files", "File data", multiple=TRUE)
      ),
      mainPanel(
          tableOutput("filetable")
      )
  ))</code></p>
  
  <h3>server.R</h3>
  
  <p><code>shinyServer(function(input, output) {
      output$filetable &lt;- reactiveTable(function() {
          if (is.null(input$files)) {
          # User has not uploaded a file yet
              return(NULL)
          }
      input$files
      })
  })</code></p>
  
  <p>The issue I have is that the result got a warning: <code>reactiveTable is deprecated. Please use renderTable instead.</code> Besides that, the code does work well.</p>
  
  <p>However, after I replaced reactiveTable with renderTable, I got an error message: <code>Error: no applicable method for 'xtable' applied to an object of class "function"</code></p>
  
  <p>Any idea how to replace <code>reactiveTable</code> with <code>renderTable</code> correctly? Thanks a lot!</p>