Interface declaration in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an interface named Vehicle.

Java

public [1] Vehicle {
    void start();
}

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

Ainterface

Bclass

Cenum

Dabstract

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'class' instead of 'interface' to declare an interface.

Using 'abstract' keyword alone without 'interface'.

The keyword interface is used to declare an interface in Java.

2fill in blank

medium

Complete the code to declare a method named stop in the interface.

Java

public interface Machine {
    [1] stop();
}

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

Avoid

Bint

Cstatic

Dfinal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' as return type when no value is returned.

Using 'static' or 'final' keywords in method declaration inside interface.

Interface methods are abstract by default and usually have no return value if they perform an action, so void is appropriate here.

3fill in blank

hard

Complete the code to explicitly declare an abstract method named reset in the interface.

Java

public interface Device {
    public [1] void reset();
}

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

Aprivate

Babstract

Cfinal

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'final' keyword which is not allowed in interface methods.

Using 'private' access modifier which is invalid in interfaces.

Interface methods are implicitly abstract, so adding abstract is correct and allowed.

4fill in blank

hard

Fill both blanks to declare an interface named Calculator with a method calculate returning an int.

Java

public [1] Calculator {
    [2] calculate();
}

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

Ainterface

Bvoid

Cint

Dclass

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'class' instead of 'interface' for the first blank.

Using 'void' as return type when an int is expected.

The keyword interface declares the interface, and the method calculate returns an int.

5fill in blank

hard

Fill all three blanks to declare an interface named Printer with a method print that takes a String parameter and returns nothing.

Java

public [1] Printer {
    [2] print([3] message);
}

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

Ainterface

Bvoid

CString

Dclass

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'class' instead of 'interface' for the first blank.

Using 'int' or other types instead of 'void' for the return type.

Using incorrect parameter types instead of 'String'.

Use interface to declare the interface, void as the return type for no return value, and String as the parameter type.