Should I pass object in method parameter or in parent constructor in Java

user_19549839 0
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I have a dilemma in mind that I can't solve. Should I pass object in method parameter or in parent constructor in this case ?

First idea:

public class TempChannelsPlugin extends JolssyPlugin {

    private JDA client;
    private TempChannelsListener listener;
    private JdaCommandManager jdaCommandManager;

    @Inject
    public TempChannelsPlugin(JDA client, JdaCommandManager jdaCommandManager, TempChannelsListener listener) {
        super(Category.UTILITIES, "Temporary Channels");

        this.client = client;
        this.jdaCommandManager = jdaCommandManager;
        this.listener = listener;
    }


    @Override
    protected void setup() {
        this.registerListener(this.client, this.listener);
    }
}

And in JolssyPlugin:

protected void registerListener(JDA client, ListenerAdapter listenerAdapter) {
   this.registerListeners(client, listenerAdapter);
}

Second idea:

public class TempChannelsPlugin extends JolssyPlugin {

    private JDA client;
    private TempChannelsListener listener;
    private JdaCommandManager jdaCommandManager;

    @Inject
    public TempChannelsPlugin(JDA client, JdaCommandManager jdaCommandManager, TempChannelsListener listener) {
        super(client, Category.UTILITIES, "Temporary Channels");

        this.jdaCommandManager = jdaCommandManager;
        this.listener = listener;
    }


    @Override
    protected void setup() {
        this.registerListener(this.listener);
    }
}

And in JolssyPlugin:

protected void registerListener(ListenerAdapter listenerAdapter) {
   this.registerListeners(this.client, listenerAdapter);
}

What is the difference between these two cases? And why should I favor one case over another?

Notice that I'm using Guice for DI

discord-jda guice dependency-injection oop java
1 Answers

In my view, if method registerListener(ListenerAdapter listenerAdapter) is located into TempChannelsPlugin class:

protected void registerListener(ListenerAdapter listenerAdapter) {
   this.registerListeners(this.client, listenerAdapter);
}

then the second option is better as vatiable private JDA client; has a scope for the whole class. So there is no need to declare unnecessary parameter because we can use private JDA client; variable in any place of class TempChannelsPlugin.

UPDATE:

In my view, if method registerListener(ListenerAdapter listenerAdapter) is located to TempChannelsPlugin class, then the second option is better as vatiable private JDA client; has a scope for the whole class. So there is no need to declare unnecessary parameter.

I would mode dependency of JDA client to JolssyPlugin as you have registerListener in JolssyPlugin. By doing this we can remove one parameter from methods such as registerListener and registerListeners. So code would look like this:

public abstract class JolssyPlugin {

    protected Set<ListenerAdapter> listeners = new HashSet<>();

    protected JdaCommandManager jdaCommandManager;
    protected Category category;
    protected String name;
    private JDA jdaClient;

    public JolssyPlugin(Category category, String name, JDA jdaClient) {
        this.category = category;
        this.name = name;
        this.jdaClient = jdaClient;
    }
    
    protected abstract void setup();

    protected void registerListener( ListenerAdapter listenerAdapter) {
       this.registerListeners(client, listenerAdapter);
    }

    protected void registerListeners(ListenerAdapter... listenerAdapter) {
        List<ListenerAdapter> listeners = Arrays.asList(listenerAdapter);

        client.addEventListener(listeners);
        this.listeners.addAll(listeners);
    }
}
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