Question

I have a simple class that has a property called “executor” in which I’d like to wire in an ExecutorService, with spring 3.0. I followed the documentation which states you simply use the factory class (in this case Executors) and supply factory-method to create your service. However, when I try to wire the resulting bean into my class, it seems that spring thinks the class type is java.lang.String instead of ExecutorService.

I have no idea what I’m doing wrong here. I seem to be correct if I look at the documentation, but perhaps I need to somehow indicate the resulting class of calling the factory method?

Here’s the error:

java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [java.util.concurrent.ExecutorService] for property ‘executor’: no matching editors or conversion strategy found

With this configuration:

<bean id="taskManager" class="examples.TaskManager">
    <property name="executor">
        <idref local="executorService" />
    </property>
</bean>
<bean id="executorService" class="java.util.concurrent.Executors" 
  factory-method="newSingleThreadExecutor" 
  destroy-method="shutdownNow" />

and this class:

public class TaskManager {

    private ExecutorService executor;

    public ExecutorService getExecutor() {
        return executor;
    }

    public void setExecutor(ExecutorService executor) {
        this.executor = executor;
    }   
}

Answer 1

Try simple ref attribute instead of idref:

<bean id="taskManager" class="examples.TaskManager">
    <property name="executor" ref="executorService" />
</bean>

and see here that the meaning of idref is passing the referenced bean’s name (as a String) to the property.

Oh, and here’s the Spring doc itself:

The idref element

The idref element is simply an error-proof way to pass the id (string
value – not a reference) of another bean in the container to a
or element.