CODEWITHSUNDEEP
javadependency-injectionguice
AlexeiOst
AlexeiOst

Reputation: 630

Deferred binding to instance using Guice

I have this in my module:

@Override
protected void configure() {
    bind(Authenticator.class).toInstance(KerberosAuthenticator.create());
}

And the reason for binding to instance here is because Kerberos authentication needs a bit of initialization like so:

    public static KerberosAuthenticator create() {
    KerberosAuthenticator auth = new KerberosAuthenticator();
    auth.start();
    return auth;
}

This works. I particularly like the fact that it works without noise like factories and providers... Can I somehow defer creating this instance. Obviously the create() method is called at the time I am configuring the binding. In this case the creation is not expensive, but in other cases it may be, or, perhaps, not even needed... I am, somehow, missing it in the Guice docs... Thank you.

Upvotes: 1

Views: 251

Answers (2)

Olivier Grégoire
Olivier Grégoire

Reputation: 35477

You could simply write a provider method:

@Provides
Authenticator provideAuthenticator() {
  KerberosAuthenticator auth = new KerberosAuthenticator();
  auth.start();
  return auth;
}

This meets your requirement of lazyness because (from the page):

Whenever the injector needs an instance of that type, it will invoke the method.

Upvotes: 0

hunter
hunter

Reputation: 4183

use Provider,

bind(Authenticator.class) .toProvider(AuthenticatorProvider.class)

check this

https://github.com/google/guice/wiki/ProviderBindings

Upvotes: 1

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