Initializing a spring bean with command line arguments

Question

What is the best way to map command line parameters to an object from the main class, and then access them from another class? I have tried with the below, but get an error message: Non-static method cannot be referenced from a static context . As it's not possible for me to make the methods in AppConfig static, what else can I do?

I am trying to initialise a spring bean with command line arguments and this is one way I thought of doing it.

I've just seen I can do what I need for now using a singleton to hold the values before instantiating the beans, and referencing the singleton in the bean. Although this sounds obvious I cannot for the life of me see how to do this with an annotated class. What can I try next?

Launcher.java

public class Launcher {

   public static void main(String [] args) throws Throwable {
       AppConfig appConfig = new AppConfig();
       appConfig.setParam1(args[0]);
       appConfig.setParam2(args[1]); 
       
       AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppContext.class);
       ...
   }

}

AppConfig.java

public class AppConfig {
       private String param1;
       private String param2;                

       public String getParam1() {
             return param1;
       }

       public String setParam1(String param1) {
             this.param1 = param1;
       }

       public String getParam2() {
             return param2;
       }

       public String setParam2(String param2) {
             this.param2 = param2;
       }
}

AppContext.java

@Configuration
@ComponentScan(basePackageClasses = Launcher.class)
@Slf4j
public class AppContext {
       AppConfig appConfig = new AppConfig();

       private final String PARAM_1 = appConfig.getParam1();  
       private final String PARAM_2 = appConfig.getParam2();                 
}

The alternative for me is to re-instantiate the class again within AppContext, but does that mean I lose access to the command line arguments getting passed through:

@Configuration
@ComponentScan(basePackageClasses = Launcher.class)
@Slf4j
public class AppContext {
       

       private final String PARAM_1 = AppConfig.getParam1();  
       private final String PARAM_2 = AppConfig.getParam2();                 
}

Answer 1

The way you're using private final String PARAM_1 = AppConfig.getParam1(); requires that the method String getParam1() MUST be static. Although I do not see it as usual approach.