How to check why #BeanInject in Camel does not initialize member? - nullpointerexception

Question

I have the following context configuration:
<bean id="propertiesFactory" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="ignoreResourceNotFound" value="true"/>
<property name="locations">
<list>
<value>classpath:conf.properties</value>
</list>
</property>
</bean>
<bean id="bridgePropertyPlaceholder" class="org.apache.camel.spring.spi.BridgePropertyPlaceholderConfigurer">
<property name="properties" ref="propertiesFactory"/>
</bean>
<bean id="messageThrottlerHolder" class="foo.bar.common.MessageThrottlerHolder"/>
<bean id="cassandraRoute" class="foo.bar.routes.CassandraRouteBuilder"/>
Then in both classes: MessageThrottlerHolder and in CassandraRouteBuilder there is:
#BeanInject
Properties properties;
Wonderful.
But CassandraRouteBuilder may/could use properties without NPE, as properties are well initialized.
On the other hand the MessageThrottlerHolder is not able to use properties as in the constructor properties are null and there is no way to initialize them.
How can I check why properties are null?
What can be wrong, that #BeanInject somehow does not initialize properties?

Answer 1

You are doing this wrong if you think that Properties are somehow Camel property placeholder or anything like that.
Camel's #BeanInject is for looking up bean in the Camel register via a bean name/id, as a poor-mans Spring IoC. If you are using Spring then you can use the Spring #Autowired or whatever they have for that.
If you want to access properties from the properties placeholder, then you can inject CamelContext and use its API for resolving: http://static.javadoc.io/org.apache.camel/camel-core/2.20.0/org/apache/camel/CamelContext.html#resolvePropertyPlaceholders-java.lang.String-
Or use Camel's #PropertyInject instead where you specify the key name to lookup. I am not sure if Spring has any similar annotation for looking up properties, as you have turned on the camel-spring bridge. You can also try to look into that.