Visitor pattern in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the Visitor interface method for visiting an Element.

LLD

interface Visitor {
    void visit([1] element);
}

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AElement

BVisitor

CObject

DElementVisitor

Attempts:

3 left

💡 Hint

Common Mistakes

Using Visitor as parameter type instead of Element.

Using Object which is too generic.

The Visitor interface defines a visit method that takes an Element object to perform operations on it.

2fill in blank

medium

Complete the code to implement the accept method in the Element class that accepts a Visitor.

LLD

class Element {
    void accept([1] visitor) {
        visitor.visit(this);
    }
}

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AObject

BElement

CVisitor

DElementVisitor

Attempts:

3 left

💡 Hint

Common Mistakes

Using Element as parameter type instead of Visitor.

Using Object which is too generic.

The accept method takes a Visitor object and calls its visit method passing itself.

3fill in blank

hard

Fix the error in the ConcreteVisitor class method signature for visiting an Element.

LLD

class ConcreteVisitor implements Visitor {
    public void visit([1] element) {
        // operation implementation
    }
}

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AConcreteElement

BElement

CObject

DVisitor

Attempts:

3 left

💡 Hint

Common Mistakes

Using ConcreteElement which is more specific than the interface.

Using Visitor or Object which do not match the interface.

The ConcreteVisitor must implement the visit method with the Element parameter type as declared in Visitor interface.

4fill in blank

hard

Fill both blanks to complete the double dispatch call in the client code.

LLD

Element element = new ConcreteElement();
Visitor visitor = new ConcreteVisitor();
element.[1](visitor);
visitor.[2](element);

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Aaccept

Bvisit

Cexecute

Dhandle

Attempts:

3 left

💡 Hint

Common Mistakes

Using execute or handle which are not standard Visitor pattern methods.

Swapping accept and visit method calls.

The client calls accept on the element passing the visitor, then visitor calls visit on the element to perform operation.

5fill in blank

hard

Fill all three blanks to complete the Visitor pattern structure with multiple elements and visitors.

LLD

interface Visitor {
    void visit([1] elementA);
    void visit([2] elementB);
}

class ConcreteVisitor implements Visitor {
    public void visit([3] elementA) {
        // implementation
    }
    public void visit(ElementB elementB) {
        // implementation
    }
}

Drag options to blanks, or click blank then click option'

AElementA

BElementB

DElementC

Attempts:

3 left

💡 Hint

Common Mistakes

Using ElementC which is not declared in the interface.

Mismatching parameter types between interface and implementation.

The Visitor interface declares visit methods for each Element type. ConcreteVisitor implements these methods with matching parameter types.