Implementing interfaces in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an interface named Printable.

Java

public interface [1] {
    void print();
}

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APrintInterface

BPrint

CPrinter

DPrintable

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class name instead of an interface name.

Misspelling the interface name.

The interface name must match the declaration. Here, Printable is the correct name.

2fill in blank

medium

Complete the code to make class Document implement the Printable interface.

Java

public class Document [1] Printable {
    public void print() {
        System.out.println("Printing document...");
    }
}

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Ainherits

Bextends

Cimplements

Duses

Attempts:

3 left

💡 Hint

Common Mistakes

Using extends instead of implements.

Forgetting to implement all interface methods.

In Java, a class implements an interface using the implements keyword.

3fill in blank

hard

Fix the error in the class by correctly overriding the print method from the Printable interface.

Java

public class Report implements Printable {
    public void [1]() {
        System.out.println("Report printing...");
    }
}

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Aprint

BPrint

Cdisplay

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase 'P' in method name.

Using a different method name than declared in the interface.

The method name must exactly match the interface method name, including case sensitivity.

4fill in blank

hard

Fill both blanks to declare an interface and a class that implements it.

Java

public interface [1] {
    void display();
}

public class Screen [2] Displayable {
    public void display() {
        System.out.println("Displaying screen...");
    }
}

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ADisplayable

Bextends

Cimplements

DDisplay

Attempts:

3 left

💡 Hint

Common Mistakes

Using extends instead of implements for interfaces.

Mismatching interface names.

The interface is named Displayable and the class uses implements to connect to it.

5fill in blank

hard

Fill all three blanks to create an interface, implement it in a class, and override the method.

Java

public interface [1] {
    String getName();
}

public class User [2] Named {
    @Override
    public String [3]() {
        return "User";
    }
}

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ANamed

Bimplements

CgetName

Dextends

Attempts:

3 left

💡 Hint

Common Mistakes

Using extends instead of implements for interfaces.

Incorrect method name or signature.

Mismatching interface name.

The interface is Named, the class User implements it, and overrides the getName method.