 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / First Aid / February 2006non-static method error -- servlet..
I'm getting the non-static method error.. this is for a servlet.. I'm trying to use getMimeType() method, which is a method of ServletContext; I have read Roedy's page.. http://mindprod.com/jgloss/compileerrormessages.html#NONSTATICCANTBEREF but: ServletContext is an interface, which means you can't create an object from it.. (come to think of it, how come we can use Interface HttpServletRequest in servlets without saying "implements HttpServletRequest"?) i.e., public class myServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) aren't we instantiating HttpServletRequest here? which is an interface.. thank you very much.. Frances > I'm getting the non-static method error.. this is for a servlet.. > I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 5 lines] > ServletContext is an interface, which means you can't create an object > from it.. Yes, you can't *create* an instance of ServletContext. But you *get* an instance, by using appropriate get...() methods. The Servlet interface has the method public ServletConfig getServletConfig() and the ServletConfig interface in turn has the method public ServletContext getServletContext() Hence, within your servlet you can do ServletContext context = this.getServletConfig().getServletContext(); String mimeType = context.getMimeType(....); You see: it's just an exercise in looking through the API docs ;-) > (come to think of it, how come we can use Interface HttpServletRequest in > servlets without saying "implements HttpServletRequest"?) [quoted text clipped - 7 lines] > aren't we instantiating HttpServletRequest here? which is an interface.. > thank you very much.. No, you are not. Instead the servlet container has instantiated the HttpServletRequest somehow (you don't know how, and you don't care). Then the servlet container called your servlet's doGet(...) method, passing the HttpServletRequest to you.  Signature"TFritsch$t-online:de".replace(':','.').replace('$','@') >>I'm getting the non-static method error.. this is for a servlet.. >>I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 16 lines] > String mimeType = context.getMimeType(....); > You see: it's just an exercise in looking through the API docs ;-) thank you.. I did look in docs... was looking for something like ServletContext.getInstance()... (I guess from now when looking to "instantiate" an interface will look for any get<InterfaceName>() method throughout API..) thanks again.. Frances > I'm getting the non-static method error.. this is for a servlet.. > I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 5 lines] > ServletContext is an interface, which means you can't create an object > from it.. ServletContext context = getServletContext(); > (come to think of it, how come we can use Interface HttpServletRequest > in servlets without saying "implements HttpServletRequest"?) [quoted text clipped - 9 lines] > > Frances Signaturetrippy mhm31x9 Smeeter#29 WSD#30 sTaRShInE_mOOnBeAm aT HoTmAil dOt CoM NP: "I Am The Law" -- Anthrax "Now, technology's getting better all the time and that's fine, but most of the time all you need is a stick of gum, a pocketknife, and a smile." -- Robert Redford "Spy Game" > > I'm getting the non-static method error.. this is for a servlet.. > > I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 7 lines] > > ServletContext context = getServletContext(); It won't work if you don't use. ServletConfig config = getServletConfig(); ServletContext context = config.getServletContext(); in the init() method first in some related servlet first. Sorry, guess I should have mentioned that. My bad. > > (come to think of it, how come we can use Interface HttpServletRequest > > in servlets without saying "implements HttpServletRequest"?) [quoted text clipped - 9 lines] > > > > Frances Signaturetrippy mhm31x9 Smeeter#29 WSD#30 sTaRShInE_mOOnBeAm aT HoTmAil dOt CoM NP: "I Am The Law" -- Anthrax "Now, technology's getting better all the time and that's fine, but most of the time all you need is a stick of gum, a pocketknife, and a smile." -- Robert Redford "Spy Game" >>>I'm getting the non-static method error.. this is for a servlet.. >>>I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 12 lines] > ServletConfig config = getServletConfig(); > ServletContext context = config.getServletContext(); yes noticed, since ServletContext.getServletContext() doesn't work.. and was confused at first b/c looked in API and found a bunch of getServletContext() methods, but none of them is of ServletContext interface.. thank you very much for your response, works now... > in the init() method first in some related servlet first. > > Sorry, guess I should have mentioned that. My bad. > >>>I'm getting the non-static method error.. this is for a servlet.. > >>>I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 19 lines] > > thank you very much for your response, works now... NP. Glad it helped. > > in the init() method first in some related servlet first. > > > > Sorry, guess I should have mentioned that. My bad. Signaturetrippy mhm31x9 Smeeter#29 WSD#30 sTaRShInE_mOOnBeAm aT HoTmAil dOt CoM NP: "I Am The Law" -- Anthrax "Now, technology's getting better all the time and that's fine, but most of the time all you need is a stick of gum, a pocketknife, and a smile." -- Robert Redford "Spy Game" >>>>>I'm getting the non-static method error.. this is for a servlet.. >>>>>I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 22 lines] > > NP. Glad it helped. thanks for all yr help, trippy.. I had also tried this, public class myServlet extends HttpServlet implements ServletContext { and it wouldn't compile.. why is this.. thanks again.. Frances > >>>>>I'm getting the non-static method error.. this is for a servlet.. > >>>>>I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 28 lines] > > and it wouldn't compile.. why is this.. thanks again.. Frances Context isn't a reserved word like out, or request or response or session. You could have this for instance: ServletContext fred = config.getServletContext() and fred would work where context would normally be.(I do use context though, because it's a hell of a lot easier to remember than anything else.) The return type for a config.getServletContext() is a ServletContext object. That's why you can use the interface without implementing it because you already get that return type back from the method call. A similar thing would be like using Enumeration en = somePropertiesObject.keys(); Signaturetrippy mhm31x9 Smeeter#29 WSD#30 sTaRShInE_mOOnBeAm aT HoTmAil dOt CoM NP: "I Am The Law" -- Anthrax "Now, technology's getting better all the time and that's fine, but most of the time all you need is a stick of gum, a pocketknife, and a smile." -- Robert Redford "Spy Game" >public class myServlet extends HttpServlet { > protected void doGet(HttpServletRequest request, HttpServletResponse >response) > >aren't we instantiating HttpServletRequest here? which is an interface.. > thank you very much.. see http://mindprod.com/jgloss/interface.html http://mindprod.com/jgloss/interfacevsabstract.html SignatureCanadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. > I'm getting the non-static method error.. this is for a servlet.. > I'm trying to use getMimeType() method, which is a method of [quoted text clipped - 5 lines] > ServletContext is an interface, which means you can't create an object > from it.. Right, you have to implement it in a class, or have an object who's class has implemented it. To use ServletContext.getMimeType() you need an object who's class has implemented the interface. For a servlet you can get this from the GenericServlet.getServletContext() method, ie. this.getServletContext() will return an object which has implemented the ServletContext interface. > (come to think of it, how come we can use Interface HttpServletRequest > in servlets without saying "implements HttpServletRequest"?) Some class implements it, and you get an object of that class. > i.e., > [quoted text clipped - 4 lines] > aren't we instantiating HttpServletRequest here? which is an interface.. > thank you very much.. No. The class of which "request" is an instance has implemented it. You don't need to know what class "request" is an instance of, all you need to know is that this class has implemented the HttpServletRequest interface. this allows you to invoke methods from that interface on the request object. It means that the object which is passed as the first parameter to the doGet() method can be of any class provided it implements the interface. HttpServletRequest isn't being instantiated, but a class which implements it has been. SignatureNigel Wade, System Administrator, Space Plasma Physics Group, University of Leicester, Leicester, LE1 7RH, UK E-mail : nmw@ion.le.ac.uk Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555 Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.