Why do I get the error named "NoSuchBeanDefinitionException: No bean named 'database'-CodePudding

After initializing context like this in my spring project :

AnnotationConfigApplicationContext context = 
            new AnnotationConfigApplicationContext();

after that I've tried to refresh the config file before calling "getBean()" :

context.refresh(); // explicit refresh of the config file.

and then :

ICustomerDal customerDal
        = context.getBean("database", ICustomerDal.class);
    customerDal.add();

But in the end I've got the "NoSuchBeanDefinitionException: No bean named 'database' available" error.

ICustomerDal.class File :

package com.springdemo;

public interface ICustomerDal {
    void add();
}

MySqlCustomerDal.class File :

package com.springdemo;

import org.springframework.stereotype.Component;

@Component("database")
public class MySqlCustomerDal implements ICustomerDal {
    String connectionString;
    // Getter
    public String getConnectionString() {
        return connectionString;
    }
    // Setter
    public void setConnectionString(String connectionString) {
        this.connectionString = connectionString;
    }
    @Override
    public void add() {
        System.out.println("Connection String : "   this.connectionString);
        System.out.println("Added to MySQL Database!"); // MySQL Codes.
        
    }
}

IocConfig.class File:

package com.springdemo;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("com.springdemo")
public class IocConfig {

}

But if I do it like the code block below, there is no error :

AnnotationConfigApplicationContext context = 
            new AnnotationConfigApplicationContext("com.springdemo"); // implicitly registering and refreshing config file.

    ICustomerDal customerDal = context.getBean("database", ICustomerDal.class);
    customerDal.add();

I just couldn't understand that if I get "NoSuchBeanDefinitionException" in the first scenario, how come I get no error just after passing the package name in ApplicationContext parameter?

Thank you in advance for your precious thoughts.

CodePudding user response：

For anyone who could encounter the same issue here :

Actually I have managed to comprehend and solve the situation here.

I realized that I need to specify the config file either in ApplicationContext or manually by registering.

Also we can specify the config file like this for another bonus method :

new AnnotationConfigApplicationContext(IocConfig.class); // Specifying the exact class name rather than the package name itself.

And using the code below helped me for another method instead of passing a parameter into "AnnotationConfigApplicationContext" :

   context.register(IocConfig.class); // --> To specify the config file. 
   context.refresh();                 // --> Need to explicitly refresh the config file after registering.