Constrained ada type in Java

[Ed Trubia]

Have the following type that applies contraints. How could this be easily
coded in Java

type ET_ACTIVE_PORT_ CONFIGURATION is
( HDX_TX1_RX1,
HDX_TX2_RX2,
HDX_TX1_RX2,
HDX_TX2_RX1,
FDX_TX1_RX2,
FDX_TX2_RX1);

for ET_ACTIVE_PORT_ CONFIGURATION use
( HDX_TX1_RX1 => 62,
HDX_TX2_RX2 => 23,
HDX_TX1_RX2 => 34,
HDX_TX2_RX1 => 45,
FDX_TX1_RX2 => 54,
FDX_TX2_RX1 => 61);

[Brad BARCLAY]

Re: Constrained ada type in Java

Ed Trubia wrote:[color=blue]
> Have the following type that applies contraints. How could this be easily
> coded in Java[/color]

There isn't really an elegant way of handling such things in Java as
you can in Ada.

For type constraining, you'll probably want to create a class which
manages these constraints. Thus, if you want an integer type that can
only hold the ranges -45..150 (say, for storing temperature data),
create a class to hold it and ensure that the value it holds doesn't
exceed on underceed that range. For example:

public class TemperatureData {
private int temp = 0;

public TemperatureData (int t) throws OutOfBoundsExce ption {
setTemp(t);
}

public setTemp(int t) throws OutOfBoundsExce ption {
if (t<-45 || t>150) throw new OutOfBoundsExce ption;
else temp=t;
}

public getTemp() {
return temp;
}
}

(Note that you'd have to also define OutOfBoundsExce ption, as it
doesn't already exist).

To handle method-level constraints, you'll have to test each variable
you want to constrain at the beginning of the method call, and then
throw an exception if it's out-of-bounds. The setTemp() method above
does just this.

As I said, there isn't any nice way to do this like there is in Ada. I
was never completely sold on Ada, but this is one of the things I miss
(along with being able to call functions with your parameters in
whatever order you want to provide them in).

Brad BARCLAY

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