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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: Problem with for
Date: Sun, 27 Apr 2014 14:04:25 -0400
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On 4/27/2014 1:55 PM, Venom Lust wrote:
>      public void writeText(String text)
>      {
>          char tmpchar;
>          int a = text.length();
>          for(int i = 0 ; i < text.length();i++);

     The `for' statement executes its subordinate statement multiple
(usually) times.  That subordinate statement is usually a {}-enclosed
block, but can be a simple statement.  What you've written is a `for'
whose subordinate statement is just `;', the empty statement.  So,
your code will execute `;' once for each `i' value, then forget all
about `i' and move ahead to the statement after the `for' ...

>          {
>              jTextArea1.setText(jTextArea1.getText() + text.charAt(i));
>              try {
>                  Thread.sleep(500);
>              } catch (InterruptedException ex) {
>                  Logger.getLogger(IJFMain.class.getName()).log(Level.SEVERE, null, ex);
>              }
>          }

... which happens to be a {}-enclosed block. But this block has nothing
to do with the `for', and is just a stand-alone bunch of code.  The code
refers to a variable named `i', but there's no such variable -- there
once was an `i' that was part of the `for', but the `for' is long gone.

>
> it says at text.charAt(i) that i doesnt exists and at for it says something like supress warning empty statement.
>
> anyone knows whats happening?

     Two things are happening. One, you don't know how to make a good
problem report: When you're puzzled by an error message, *quote* the
message and don't report "it says something like."

     Two, you've got a semicolon that you don't want.

-- 
Eric Sosman
esosman@comcast-dot-net.invalid