CODEWITHSUNDEEP
javaspringdependency-injectionconstructorframeworks
Gregory
Gregory

Reputation: 65

Dependency Injection in constructors

I have problem with my code using dependency injection in constructors. I have three constructors in my class:

public class Meal {
private Ingredients ingredient;
private String text; 
private int;

public Meal(Ingredients ingredient) {
    this.ingredient = ingredient;
}

public Meal(String text) {
    this.text = text;
}

public Meal(int number) {
    this.number = number;
}
}

In bean configuration file it looks like this:

    <bean id="ingredient"
    class="mytest.Sugar"
></bean>

<bean id="myMeal" 
    class="mytest.Meal">
    <constructor-arg ref="ingredient"/>     
    <constructor-arg type="java.lang.String" value="hello"/>
    <constructor-arg type="int" value="1"/>

</bean>

After compiling I've got such an error: 

WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myMeal' defined in class path resource [app.xml]: Could not resolve matching constructor (hint: specify index/type/name arguments for simple parameters to avoid type ambiguities)
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myMeal' defined in class path resource [app.xml]: Could not resolve matching constructor (hint: specify index/type/name arguments for simple parameters to avoid type ambiguities)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:243)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1270)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1127)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:758)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
at mytest.MainApp.main(MainApp.java:9)

and I don't know how to fix it. Can someone help me?

Upvotes: 0

Views: 201

Answers (1)

Kedar Joshi
Kedar Joshi

Reputation: 1511

Your configuration of bean myMeal has three constructor arguments while the actual constructor has only one.

Either remove <constructor-arg type="java.lang.String" value="hello"/> and <constructor-arg type="int" value="1"/> from the configuration or add corresponding missing arguments to the constructor of the class Meal.

In short, you need to have all the arguments in a single constructor and not in separate constructors.

Upvotes: 2

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