Constructor injection, int vs Integer

[andbin]

Hi, I have a simple class:

public class TestBean1 {
    private String info;

    public TestBean1(String v) {
        info = "Constructor: TestBean1(String)";
    }

    public TestBean1(int v) {
        info = "Constructor: TestBean1(int)";
    }

    public TestBean1(Integer v) {
        info = "Constructor: TestBean1(Integer)";
    }

    public TestBean1(Number v) {
        info = "Constructor: TestBean1(Number)";
    }

    public String toString() {
        return info;
    }
}

and the following XML configuration (only the relevant part):

    <bean id="anInteger" class="java.lang.Integer">
        <constructor-arg value="123456"/>
    </bean>

    <bean id="bean1_a" class="TestBean1">
        <constructor-arg value="123"/>
    </bean>

    <bean id="bean1_b" class="TestBean1">
        <constructor-arg type="int" value="123"/>
    </bean>

    <bean id="bean1_c" class="TestBean1">
        <constructor-arg type="java.lang.Integer" value="123"/>
    </bean>

    <bean id="bean1_d" class="TestBean1">
        <constructor-arg ref="anInteger"/>
    </bean>

    <bean id="bean1_e" class="TestBean1">
        <constructor-arg type="java.lang.Integer" ref="anInteger"/>
    </bean>

    <bean id="bean1_f" class="TestBean1">
        <constructor-arg type="java.lang.Number" ref="anInteger"/>
    </bean>

    <bean id="bean1_g" class="TestBean1">
        <constructor-arg type="int" ref="anInteger"/>
    </bean>

and this in a test class:

        XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource("constructor-arg-test.xml"));

        String[] beanNames = {
            "bean1_a", "bean1_b", "bean1_c", "bean1_d", "bean1_e",
            "bean1_f", "bean1_g"
        };

        for (String beanName : beanNames) {
            System.out.print("bean \"" + beanName + "\" --> ");
            System.out.println(factory.getBean(beanName));
        }

The output is:

bean "bean1_a" --> Constructor: TestBean1(String)
bean "bean1_b" --> Constructor: TestBean1(int)
bean "bean1_c" --> Constructor: TestBean1(Integer)
bean "bean1_d" --> Constructor: TestBean1(int)
bean "bean1_e" --> Constructor: TestBean1(Integer)
bean "bean1_f" --> Constructor: TestBean1(Number)
bean "bean1_g" --> Constructor: TestBean1(int)

It's all quite clear to me ... except for one thing: the bean "bean1_d". Since the ref is to an Integer object, initially I would have expected that TestBean1(Integer) was called. But instead TestBean1(int) is called.

Why? I could think that conversion to a primitive is preferred over an "identity" assignment, is it right?
Thank.