How do you catch enter key as an error in java eclipse?
<p>this is what i'm trying to do: </p>

<p>User enters numbers into the program and program does stuff with it. </p>

<p>but if the user were to just type the "enter" key (or "return" key) eclipse says   </p>

<blockquote>
  <p>Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 0</p>
</blockquote>

<p>what i need for eclipse to say is "invalid input" and ask for the input again. </p>

<p>This is how i am getting the input: </p>

<p>I am using one buffered reader in one function, and i am calling the function whenever i need to read input from the user. Here are my codes for this function incase you want to refer to it. Also, the program is a coverage optimization program, incase you wanted to know that as well. Thank you so much for your help!</p>

<pre><code>public static String Reader() {
  BufferedReader nerd = new BufferedReader(new InputStreamReader(System.in));
  String rvalue = "0";
  try {
    rvalue = nerd.readLine();
    if(elements_typed == 0) {
      Integer.parseInt(rvalue);
    }
    if(sets_typed == 0) {
      Integer.parseInt(rvalue);
    }
    return rvalue; 
  } catch (IOException e) {
    System.out.print("ERROR: Input must be an integer in [1, infinity]!");
    display_menu();
  } catch (NumberFormatException e) {
    System.out.print("ERROR: Input must be an integer in [1, infinity]!\n\n");  
    if(elements_typed == 0) {
      System.out.print("Enter number of elements (n):\n");
      rvalue = Reader();
    }
    if(sets_typed == 0) {
      System.out.print("Enter number of sets (n):\n");
      rvalue = Reader();
    }
  }
  return rvalue;
}
</code></pre>
