import javax.annotation.PreDestroy (1)
import java.util.concurrent.atomic.AtomicBoolean
import javax.inject.Singleton
@Singleton
class PreDestroyBean implements AutoCloseable {
    AtomicBoolean stopped = new AtomicBoolean(false)
    @PreDestroy (2)
    @Override
    void close() throws Exception {
        stopped.compareAndSet(false, true)
    }
}

import javax.annotation.PreDestroy
import javax.inject.Singleton
import java.util.concurrent.atomic.AtomicBoolean
@Singleton
class PreDestroyBean : AutoCloseable {
    internal var stopped = AtomicBoolean(false)
    @PreDestroy (2)
    @Throws(Exception::class)
    }
}

For factory beans, the preDestroy value in the annotation can be used to tell Micronaut which method to invoke.

import io.micronaut.context.annotation.Bean
import io.micronaut.context.annotation.Factory
import javax.inject.Singleton
@Factory
class ConnectionFactory {
    @Bean(preDestroy = "stop") (1)
    @Singleton
    Connection connection() {
        new Connection()
    }
}

import io.micronaut.context.annotation.Bean
import io.micronaut.context.annotation.Factory
import javax.inject.Singleton
@Factory
class ConnectionFactory {
    fun connection(): Connection {
        return Connection()
    }
}

import java.util.concurrent.atomic.AtomicBoolean
class Connection {
    AtomicBoolean stopped = new AtomicBoolean(false)
    void stop() { (2)
        stopped.compareAndSet(false, true)
    }
}

import java.util.concurrent.atomic.AtomicBoolean
class Connection {
    internal var stopped = AtomicBoolean(false)
    fun stop() { (2)
        stopped.compareAndSet(false, true)
    }
}