CODEWITHSUNDEEP
corda
Tywin Lannister
Tywin Lannister

Reputation: 164

Can my @InitiatingFlow be a Generic class?

Is it possible to define an @InitiatingFlow as a generic class?:

@InitiatingFlow
public class FungibleStateIssueSend<T extends Oil> extends FlowLogic<SignedTransaction> {...}

...If I try I get a compile error on the @InitiatedBy annotation in the receiving flow:

@InitiatedBy(FungibleStateIssueSend.class)
public class FungibleStateIssueReceive extends FlowLogic<Void> {...}

Error:

Incompatible types. Found: 'java.lang.Class<com.template.flows.FungibleStateIssueSend>', required: 'java.lang.Class<? extends net.corda.core.flows.FlowLogic<?>>'

Here is how I was going to use it:

// Define the delivery unit (bbl, m3 or tonne) and corresponding API of the oil in that unit:
WtiBbl wtiBbl = new WtiBbl(new BigDecimal("4.5"));

// Set Amount of units for delivery:
Amount<WtiBbl> amountWtiBbl = new Amount<>(1_000L, wtiBbl);

// Create a FungibleState so the delivery can be divided between different shippers:
OilFungibleState<WtiBbl> juneProduction = new OilFungibleState<>(Month.JUNE, Collections.singletonList(partyA), amountWtiBbl);

// Issue the FungibleState onto the ledger...
FungibleStateIssueSend<WtiBbl> fungibleStateIssueSend = new FungibleStateIssueSend<>(juneProduction);
CordaFuture<SignedTransaction> future = partyANode.startFlow(fungibleStateIssueSend);
mockNetwork.runNetwork();

SignedTransaction signedTransaction = future.get();

I can work around the limitation. I just want to understand if this is a Corda thing or a Java thing?

Upvotes: 0

Views: 69

Answers (1)

Ashutosh Meher
Ashutosh Meher

Reputation: 1821

It feels like its more of a Java thing.

For example, if I use a wild card for the class type it works fine with generic typed parameter.

@Target(ElementType.TYPE_USE)
@Retention(RetentionPolicy.RUNTIME)
@interface TestAnnotation{
    public Class<?> value();
}

So I can use the annotation @TestAnnotation(Initiator.class) in a class, while Initiator could be defined as:

public static class Initiator<T> extends FlowLogic<SignedTransaction>

But when we bound the wildcard to something below, the compiler complains.

@Target(ElementType.TYPE_USE)
@Retention(RetentionPolicy.RUNTIME)
@interface TestAnnotation{
    public Class<? extends FlowLogic<?>> value();
}

But if we remove the wildcard from the FlowLogic it works. Not sure why the compiler complains because of that wildcard.

Upvotes: 1

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