OO: new class implementing requires additional parameter

Question

let's say i have an interface as below public interface ConditionChecker { boolean isInCondition(Person p); } I want to create a new class implementing the above interface but i need to implement a function with another parameter public class MacroConditionChecker implements ConditionChecker { public boolean isInCondition(Person p, MacroView mv); } Two problems: One: if i change the interface signature to boolean isInCondition(Person p, MacroView mv); then i need to update all the classes implementing ConditionChecker Two: I want the consumers of ConditionChecker to just call isInCondition as-is I think that means: public class MacroConditionChecker implements ConditionChecker { private static final MacroView mv; public MacroConditionChecker(MacroView mv) { this.mv = mv; } public boolean isInCondition(Person p){ // now i have access to MacroView } } so, the only change i need is make at the time I decide to use MacroConditionChecker and the call to isInCondition is not changed Am i on the right track? or Is there some way else to accomplish this? or should i separate out MacroView as its own interface public class MacroConditionChecker implements ConditionChecker implements MacroView JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

ConditionChecker reminds Command design pattern. Comment from the linked page: Command decouples the object that invokes the operation from the one that knows how to perform it. To achieve this separation, the designer creates an abstract base class that maps a receiver (an object) with an action (a pointer to a member function). The base class contains an execute() method that simply calls the action on the receiver. This is exactly, what you need. In case you need to check only internal state of Person object it is enough. When you want to check Person object with external API that's OK to create implementation which binds external API in constructor with Person object in method. Simple example: import java.util.ArrayList; import java.util.List; public class DesignPatterns { public static void main(String[] args) { List checkers = new ArrayList<>(); checkers.add(person -> person != null); checkers.add(person -> person.getName() != null); checkers.add(person -> person.getName().length() > 0); checkers.add(new MacroViewConditionChecker(new MacroView())); checkers.add(new RestApiConditionChecker(new RestApi())); Person person = new Person(); person.setName("Name"); for (ConditionChecker checker : checkers) { System.out.println(checker.isInCondition(person)); } } } interface ConditionChecker { boolean isInCondition(Person person); } class MacroViewConditionChecker implements ConditionChecker { private final MacroView macroView; public MacroViewConditionChecker(MacroView macroView) { this.macroView = macroView; } @Override public boolean isInCondition(Person person) { return macroView != null; } } class MacroView { } class RestApiConditionChecker implements ConditionChecker { private final RestApi restApi; public RestApiConditionChecker(RestApi restApi) { this.restApi = restApi; } @Override public boolean isInCondition(Person person) { return restApi.checkName(person.getName()); } } class RestApi { public boolean checkName(String name) { System.out.println("Validate name ..."); System.out.println(name + " is valid"); return true; } } class Person { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } } You can use this pattern together with Chain of Responsibility. This approach does not bind Person object with any implementation. This bind is done in specific ConditionChecker implementation which can be easily exchanged.