Callable Functions

Mark a function as entry point to the contract.

In order for a function or method to be called from outside the contract (by a user on the blockchain, or from another contract) it needs to be annotated as @Callable.

Important:

• A @Callable function must be public and static.
• Return type and method arguments type must be a supported AVM ABI type.
• Only functions in the contract main class should be labelled as @Callable.

@Callable
public static String greet(String name) {
    return "Hello " + name;
}

If you are calling a function within contract, you do not have to assign the @Callable annotation to the function you want to call. The function to be called can be public, private or @Callable.

It is possible to have functions that do not have the @Callable annotation, and your contract will be able to compile. However, any attempt to call a non-Callable function from outside of the contract will be reverted, even if it is a public function.

One of our AVM tool, called the ABI compiler, is run on an input jar, it collects the list of methods labelled @Callable. This information is used in 2 places:

• If we generate a main method for the contract (We only generate a main method if there was no main method in the user code!).
• When generating Contract ABI.