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Java Forum / General / March 2007call method by name
Hello. I have a program that calls a method from another class. This method takes a few seconds to execute as it uses a timer. I want a way of telling the caller when the callee is finished. My idea was passing a parameter to the callee containing the name of the method to run on completion. This method would be in the caller's class. So basically, how do i pass a method name to another class so that it can be called at a later time? Or, what better ways are there to be notified after a timer using method has completed? (other than another timer as the timed code can be finished by clicking the screen) thanks! stinkinrich88@googlemail.com wrote On 03/01/07 14:41,: > Hello. I have a program that calls a method from another class. This > method takes a few seconds to execute as it uses a timer. I want a way [quoted text clipped - 8 lines] > method has completed? (other than another timer as the timed code can > be finished by clicking the screen) It's not quite clear to me what you're doing. The normal way for a callee to notify a caller that it's finished is for the callee to return ... If you're looking for something like a "callback" or a "strategy pattern," the sort of thing C uses function pointers for, that's easy: You pass the callee an object that has the method you'd like the callee to "call back" to. For example, consider how a Comparator is used; there's nothing magical about a Comparator, and you can do similar things in your own classes.  SignatureEric.Sosman@sun.com On Mar 1, 7:41 pm, "stinkinric...@googlemail.com" <stinkinric...@googlemail.com> wrote: > Hello. I have a program that calls a method from another class. This > method takes a few seconds to execute as it uses a timer. I want a way [quoted text clipped - 10 lines] > > thanks! As i understand you need to run some code in a new Thread and then notify another part when this code will be completed. If you wish that a caller part not to be blocked while executing new thread, then the better method is to use listeners; which will be notified by called method when execution will be completed. If you preffer for whatever reason to pass name of the method i think you need also pass instance of caller object. Then it is simple to call the method using java reflection api. hmm, say I had a method like this: public void show(String messageIn) { Timer time = new Timer(2000, new ActionListener() { public void actionPerformed(ActionEvent e){hide();}}); msg.setText(message); time.setRepeats(false); time.start(); setVisible(true); } public void hide() { setVisible(false); ***NOTIFY SOMEHOW**** } This displays a message on screen. The message dissapears after 2 seconds, OR when the user clicks it (an actionListener is added to it in the constructor). This means the hide method will not necisarily run after 2 seconds. When it does run I want it to notify the class that called it (a separate class) by either running a method from it or having the class wait for it somehow On Mar 1, 6:10 pm, "stinkinric...@googlemail.com" <stinkinric...@googlemail.com> wrote: > hmm, say I had a method like this: > [quoted text clipped - 21 lines] > setVisible(false); > ***NOTIFY SOMEHOW**** A. ------------------------- // add field theCaller and initialize it // at appropriate time theCaller.notifyMethodName(...); B. ------------------------- fireEndOfExecutionEvent(new MyEvent(...)); | |--> all listeners to be called > } > [quoted text clipped - 4 lines] > that called it (a separate class) by either running a method from it > or having the class wait for it somehow > On Mar 1, 6:10 pm, "stinkinric...@googlemail.com" > [quoted text clipped - 43 lines] > > that called it (a separate class) by either running a method from it > > or having the class wait for it somehow wow, that's over my head I'm afraid. Could you break it down a little please? Are A&B two separate solutions? I tried to google parts of them and I got nothing! Thanks for your help!!! > wow, that's over my head I'm afraid. Could you break it down a little > please? Are A&B two separate solutions? I tried to google parts of > them and I got nothing! Thanks for your help!!! Define an interface with some method that you want to be able to call. Create an object that implements that interface and pass it to your long-running method. When the long-running method is done, it calls the method defined by the interface on the object you passed to it. http://www.javaworld.com/javaworld/javatips/jw-javatip10.html Search for "java callback" for more examples of this common technique. /gordon Signature[ don't email me support questions or followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e > > wow, that's over my head I'm afraid. Could you break it down a little > > please? Are A&B two separate solutions? I tried to google parts of [quoted text clipped - 14 lines] > [ don't email me support questions or followups ] > g o r d o n + n e w s @ b a l d e r 1 3 . s e Ahhh! pure genius! thank you soo much. That took me ages to get my head around but it works well! I don't suppose there's any way to do this without needing an interface? ooh, can I just ask a really easy question: if I am doing lots of stuff to one thing, eg: hello.setVisible(true); hello.setColor(black); hello.shutUp(); hello.blahblahblah(); how can I get it more like: with(hello) { setVisible(true) setColor(black) ......etc what's the format? thanks!!!!!!!!!!! On Mar 2, 10:25 am, "stinkinric...@googlemail.com" <stinkinric...@googlemail.com> wrote: > > > wow, that's over my head I'm afraid. Could you break it down a little > > > please? Are A&B two separate solutions? I tried to google parts of [quoted text clipped - 41 lines] > > thanks!!!!!!!!!!!- Hide quoted text - There's no built-in support for that kind of syntax (unless a newer version has something I don't know about.... but you can use a nasty looking hack like this: Have all your setXXX methods return "this" (the instance of the class you're working with) and then you can use this syntax - hello.setVisible().setColor().etc(); I don't like it... but you could do it. - Virgil > On Mar 2, 10:25 am, "stinkinric...@googlemail.com" > [quoted text clipped - 58 lines] > > - Virgil Really? not supported? mental. I'm just use to VB6. Thanks anyway though!! and thanks for that other solution! very imaginative! 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 ...
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