Java: Hashtables and checking a element is less than value of 40

[intellix]

For an assignment, one of the tasks is to display someone with a grade less than 40. So far i've got this:
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Enumeration enumName = NameGrade.keys() ;
Enumeration enumGrade = NameGrade.elements();
txtOutput.setText("");
while ( enumGrade.hasMoreElements() ){
currently converting object to string, then to integer and checking if its less than 40
if ( Integer.parseInt((String)enumGrade.nextElement() ) < 40){
txtOutput.append("Name: " + enumName.nextElement() + " - " + enumGrade.nextElement() + "%\n" );
InputName.setText("");
InputGrade.setText("");
}else{
}
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Just isnt working :/ I input 2 people, one with a grade under and one with over 40 then click the button. At first it was displaying one person but with a different grade ;o then I changed it and it errors out showing nothing at all... I can imagine the error is blindingly obvious if anyone good with Java could check it out Hope theres enough information there..

Thanks so much, you would be saving my neck as Im really not getting any of this

 

[intellix]

thank you so much, it works properly! I get a load of errors though, even though the program still runs and seems to be doing what it needs to do. the first two of the errors are:

Exception in thread "AWT-EventQueue-0" java.util.NoSuchElementException: Hashtable Enumerator
at java.util.Hashtable$Enumerator.nextElement(Hashtable.java:1021)

Im fine to leave this lol but.. what is causing that do you think? cause they were my main concern last time, even though it wasnt showing stuff correctly too Thanks sooooo much