The signature for concat is:
String concat(String str)
Therefore,
> // this line has no effects?????why??
> //content has been initialized in the constructor as:
> //content = new String(":");
>
> content.concat(new String("~~~~~~~\n"));
would require you to do:
content = content.concat(new String("~~~~~~\n"));
Conversly, you can also do this as well:
content += "~~~~~~\n";
Or.. use a StringBuffer. It's much more efficient (it doesn't create new
String objects every time a string is concatenated). Use it's
.append(String str) method.
Erik Sahl
[EMAIL PROTECTED]
> Hi,
>
> I meet a problem in the servlets. I don't know why the
> concat()method has no
> effects.
> No error , no results. Just Like a blank line.
>
> public void doGet (HttpServletRequest request,
> HttpServletResponse response)
> throws ServletException, IOException
> {
> String ipaddress = new String(request.getRemoteAddr());
> if (!ipname.containsKey(ipaddress))
> {
>
> ipname.put(request.getRemoteAddr(),request.getParameter("name"));
> iprequest.put(request.getRemoteAddr(),request);
> ipresponse.put(request.getRemoteAddr(),response);
> }
>
> // this line has no effects?????why??
> //content has been initialized in the constructor as:
> //content = new String(":");
>
> content.concat(new String("~~~~~~~\n"));
>
> response.setContentType("text/html");
>
>
> PrintWriter out = response.getWriter();
> out.println("<html>");
> out.println("<body>");
> out.println("<FORM
> action=\"http://155.69.22.31:8080/chat/chat\"
> method=\"post\">");
> out.println("<P>");
> out.println("<LABEL for=\"We are talking!\">We are talking!:
> </LABEL><BR>");
> out.println("<TEXTAREA name=\"history\" rows=\"12\"
> cols=\"50\">");
> out.println(content);
> out.println("</TEXTAREA><BR>");
> out.println("<LABEL for=\"I am speaking!\">I am speaking!:
> </LABEL><BR>");
> out.println("<input type=text size=40 name=message>");
> out.println("<INPUT type=\"submit\" value=\"Send\"><INPUT
> type=\"reset\">");
> out.println("</P>");
> out.println("</FORM>");
> out.println("</body>");
> out.println("</html>");
> }
>
> Thanksvery much!
>
> Yang
>
>
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