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calling applet in separate frame

markoj
markoj asked
on
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Last Modified: 2012-06-27
I have 2 applets in 2 separate frames. How would one applet call another?
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There are several techniques you can use:

1)

Applet friend = getAppletContext().getApplet("Friend");

where the Friend applet is defined with <applet code = "Some.class" width=20 height=20 name="Friend">

and then use friend.method() or friend.member to estabish communication.

2)

You could use static variablesand methods which are defined and used in both classes

3)

You could use a server app to tranfer data between the applets (If they were not loaded by the same page)

or

4)

You could use threads and the ThreadGroup hierarchy (mainly for control purposes).


If you want to see documentation and samples on all these techniques, go to http://www.mcp.com and read Chapter 1 of the on-line book: Tricks of Java Programming Gurus.

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Author

Commented:
Hm. I tried 1st solution, but it doesn't seem to work. If the applets are in the same frame, then it works. If I put them in
seprate ones it stops working.
Well, that seems to leave you with static variables and methods or networks as alternatives.

Since the network solutions imply either defining your own protocol (over http tunneling) in order to exchange data, as well as establishing a polling mechanism on the server applet(s), its realy only practical for comunicating applets across networks or broser (diferen browser or browser instances) boundries.

The referance I gave you has a verry complete example on using a common class for inter applet communication, including applet registration into the shared service.

As a final alternative, you could also use RMI or CORBA establishing localhost calls. But this would probably be an overkill.

Commented:
I've done this sort of thing before - one applet in a frame , calling methods of  a 2nd  applet in another frame  , and vice-versa .
Lemme know if you  want more info .

Author

Commented:
I'd be thankful.

Author

Commented:
To jpk: I'll grade your answer as soon as I get code from priyam.
markoj,

If the code from pryam works better than my answer, F my answer an give the points to pryam.

Commented:
Hi ! I'm not doing this for points , so  it doesn't matter who you grade  (I didn't realize this question was locked - sorry jpk )
Anyway , my solution is similar to what jpk suggested .
What I've done is , used a common class with static variables , which this class uses to reference the other 2 applets in the separate frames .
Consider that appA ,appB are the 2 aplets in separate frames , and apC is the common class .
 The code in appC  is something like this ::

static appA refA ;
static appB refB ;

public void  regA(appA param)
{
refA = param ;
}
public void regB(appB param)
{
refB = param ;
}

public void  callA()
{
refA.methodA() ;
}
public void callB()
{
refB.methodB() ;
}

When appA and appB are initialised , the register themselves with appC by passing  their references as parameters to the corresponding appC methods :
----------------------
for appA :

appC refAC ;
In its init() or start() method :
refAC = new appC() ;
refAC.regA(this) ;
-------------------------------
for appB :

appC refBC ;

In its init() or start() method :
refBC = new appC() ;
refBC.regB(this) ;
---------------------------------
This way appC now has reference to both the apps .
Now if appA wants to call a public method of appC (say , methodB() ) ,
one way it could do this is by indirectly calling a public method of
appC ( callB()), which in turn  calls the public method of appB
in its method  , for example , the code in appA would be :
 refAC.callB() ;

Similarly . for appB to call appA :
refBC.callA() ;


I hope this is not too confusing -  I'm sorry if it is .
I'm unable to send you actual code at the moment - am a little tied up .
Don't worry about the grades and stuff  - it's inconsequential  - besides , jpk deserves it more than me , since I'm probably suggesting the same thing he did.

Regards,
Priya






Author

Commented:
This is exactly what I did, following jpk's instructions. So I'll grade his answer. But thank you anyway. I'm sure your answer will help others - that won't have to exepriment as much as I had to.
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