Chief Delphi - Using multiple classes in java to control one pwm

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Using multiple classes in java to control one pwm

So I'm trying to figure out how to do multiple classes. This is the strucuture of the classes, where everything in events is a system on the robot.
http://www.chiefdelphi.com/forums/at...5&d=1396919131
The problem is, I put all the pwm stuff in map, so when the second one runs it complains about that pwm already being assigned. How do I get around this?
Here is the error I get, incase I misinterpreted it:

Spoiler for blah:

Re: Using multiple classes in java to control one pwm

Can you paste your map.java?

If at any point a conflict in PWM ports is detected your project will return an error and a stacktrace like the one you pasted. You will probably need to reassign the port in code, as well as move the physical cable itself on your Digital Sidecar.

If you declare a talon object in map.java, you can just make new variables in the two other classes that point to the existing object.
Ex:
Talon motor = map.getMotor();
Or just map.motor if you make it public, but encapsulation.

Re: Using multiple classes in java to control one pwm

Quote:

Originally Posted by vgdude999 (Post 1371244)

If you declare a talon object in map.java, you can just make new variables in the two other classes that point to the existing object.
Ex:
Talon motor = map.getMotor();

@sthreet: Or this, in which case map.java would have to initialize your Talon objects with the constants, e.g.

Code:

Talon motor = new Motor(PWM_PORT_ON_DSC);

For this purpose you may want to look into the Singleton design pattern. Be careful that multiple classes aren't attempting to access the Talon object at the same time, which appears to be your initial problem.

Re: Using multiple classes in java to control one pwm

Sorry, the one I was using as map was outputmap. I called it map in all the events though. (Map is inputmap, will go ahead and rename it.)

Spoiler for outputmap:

Also, how do I make it public so I don't have to write:

Code:

import edu.wpi.first.wpilibj.templates.outputmap;



//inside of class

outputmap map=new outputmap();

every time?

Re: Using multiple classes in java to control one pwm

Quote:

Originally Posted by sthreet (Post 1371300)

Sorry, the one I was using as map was outputmap. I called it map in all the events though. (Map is inputmap, will go ahead and rename it.)

Spoiler for outputmap:

Also, how do I make it public so I don't have to write:

Code:

import edu.wpi.first.wpilibj.templates.outputmap;



//inside of class

outputmap map=new outputmap();

every time?

If you make the variables in the outputmap class static (i.e. class variables instead of instance variables), then you can access them directly without an instance.

Code:

public class outputmap 

{

    //output

    public static Talon leftdrive=new Talon(1);

    public static Talon rightdrive=new Talon(2);

...

}



// Somewhere else in the code

Talon myMotor = outputmap.leftdrive;

As was mentioned before, this is an example of the Singleton design pattern. Note that static classes are not necessarily the best way to handle this scenario. Another method is to have the class manage a single shared instance. See the WPILib DriverStation class for example.

Re: Using multiple classes in java to control one pwm

Thanks, it worked perfectly. Doesn't seem to like multiple instances.

That is really weird, that you can access a static variable when you can't access a non-static one, I can see something like public/private/semiprivate where semiprivate is the same as current public and public is the same as current public static.

I do come from python and javascript though, so not having types to variables must be weird here.

Quote:

Originally Posted by sthreet (Post 1371795)

From my (very basic) understanding, non static variables and methods can only be used if an object of their class is created. So, if you kept the talons non static, you would have to actually create an instance of the outputmap.
So,
outputmap x = new outputmap();

Static variables and methods, however, do not require this.
Please correct me if anything I said is horribly wrong :)

Re: Using multiple classes in java to control one pwm

Quote:

Originally Posted by vgdude999 (Post 1371997)

This is correct. Non-static variables belong to a specific instance of a class; each instance has it's own copy. Static variables belong to the class itself; they exist independent of an instance. Before, when the first instance of outputmap was created, it allocated the IO channels that OP was using. If a second instance was attempted, it would be trying to reallocate those IO ports. Since you can only have one instance of a given IO channel, an AllocationException was thrown.