AY18/19 Q2 Cyclical Dependency

[muhdjabir]

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Description

Helloo, was doing this question and am stumped. I understand that the console start method relies heavily on logic and Logics invokes method also requires knowledge of the Consoles methods. How would you guys approach removing the cyclical dependency for this?

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[zannlimjm]

Following the Dependency inversion principle, declare an interface between both classes to break the dependency and invert the dependence from one? So maybe console class implements the new interface while logic's argument is the interface. Hope it helps!! a little hard to explain >.<

[muhdjabir]

@zannlimjm OH! okay i get the gist of it will work on coding it out. Thanks alot1!!

[lukasleeyo]

Hi there, I have tried it out after @zannlimjm mentioned the implementation. Can anyone help to see if this is correct? Thank you!

interface Logic { void invoke(String command); }

`class Console implements Logic {
private String id;

Console(String id) {
    this.id = id;
}

void feedback(String mesg) {
    System.out.println(id + ": " + mesg);
}

@Override
public void invoke(String command) {
    this.feedback(command + " executed");
}

void start() {
    Scanner sc = new Scanner(System.in);
    String command;
    do {
        System.out.print("Enter a command: ");
        command = sc.next();
        this.invoke(command);
    } while (!command.equals("exit"));
}

}`

class Main { public static void main(String[] args) { Console console = new Console("main"); console.start(); } }