@Autowired for properies in 3.1

[Oscar G. Rodriguez]

Hello,

I'm learning Spring from the 3.1 spring_tutorial.PDF, and in @Autowired on Properties section we can read

package com.tutorialspoint; 

import org.springframework.beans.factory.annotation.Autowired; 

public class TextEditor { 
@Autowired private SpellChecker spellChecker; 

public TextEditor() { 
 System.out.println("Inside TextEditor constructor." ); }

public SpellChecker getSpellChecker( ){
 return spellChecker; } public void spellCheck(){ spellChecker.checkSpelling(); }
 }

I've understood that it works without the setter method, then I've tried

public class BeanTest {
	
	@Autowired
	private String msg;

	<context:annotation-config></context:annotation-config>
	<bean id="beanTest" class="BeanTest" init-method="init" destroy-method="destroy">
		<property name="msg" value="prueba"/>
	</bean>

without/with setter method, but always throws an exception

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

If I use the @Autowired(required=false), the msg property is injected if it's defined in the xml, and I have no exception if I comment it, but only with the setter method.

When I comment the setter method I obtain

Caused by: org.springframework.beans.NotWritablePropertyException: Invalid property 'msg' of bean class [BeanTest]: Bean property 'msg' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?

It only works with defined bean objects but not with String? Why it works with required=false? It's needed the setter method?

I'm wrong or it is an issue?

Thanks.

[Kathleen Angeles]

If you use XML to inject a property, you need a setter method.

If you @Autowired a property, you don't need a setter method.

- k

-------------------------------------------------------------------------------------------------------------
[SpringSource Certified Spring Professional - Practice Tests]

[Kathleen Angeles]

Oscar G. Rodriguez wrote:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

If you have below,

@Autowired  
private String msg;

where 'required' attribute of @Autowired is defaulted 'true', you must have a exactly 1 Spring bean in the context whose type is String.

Otherwise, you will get the exception above.


If you have below,

@Autowired(required=false)  
private String msg;

you must have a 0 or 1 Spring bean in the context whose type is String.

- k

-------------------------------------------------------------------------------------------------------------
[SpringSource Certified Spring Professional - Practice Tests]

[Oscar G. Rodriguez]

Ok, thanks a lot.

I understand that i was mixing both ways, XML and annotations.

If I want to inject a String property by @Autowire in property (only for study purpose) I need to create a String Bean like

<bean id="msg" class="java.lang.String">
	<constructor-arg value="prueba"/>
</bean>

And when I defined the required=false it worked because I was mixing both at same time, the annotation way didn't inject anything but not fail, and the XML did.

My confussion came because I didn't see a clear way to create a String bean, and I supposed that I had to use the property tag.

[Kathleen Angeles]

You're welcome.