Object interaction in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an object of the class Car.

Java

Car myCar = new [1]();

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ACar

BObject

CVehicle

Dcar

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase class name like 'car' instead of 'Car'.

Using a different class name like 'Vehicle' which is not defined.

To create an object, use the class name with the new keyword. Class names in Java start with uppercase letters.

2fill in blank

medium

Complete the code to call the method startEngine on the car object.

Java

myCar.[1]();

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AbeginEngine

BrunEngine

CengineStart

DstartEngine

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect method names like 'runEngine' or 'engineStart'.

Forgetting the parentheses after the method name.

To call a method, use the object name followed by a dot and the method name exactly as defined.

3fill in blank

hard

Fix the error in the code to access the speed attribute of the car object.

Java

int currentSpeed = myCar.[1];

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Aspeed

BcurrentSpeed

CgetSpeed()

DSpeed

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase 'Speed' instead of 'speed'.

Trying to call an attribute as a method like 'getSpeed()' if it does not exist.

Attributes are accessed by their exact name with correct case. Here, the attribute is 'speed' with lowercase 's'.

4fill in blank

hard

Fill both blanks to create a new Engine object and assign it to the car's engine attribute.

Java

myCar.engine = new [1]();
[2] engine = myCar.engine;

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AEngine

BCar

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Car' or 'Vehicle' instead of 'Engine' for the object type.

Mismatching the variable type and the object assigned.

The class name for the engine is 'Engine'. We create a new Engine object and assign it to the car's engine attribute. Then we declare a variable of type Engine to refer to it.

5fill in blank

hard

Fill all three blanks to define a method in the Car class that returns the engine's horsepower.

Java

public int [1]() {
    return this.engine.[2];
}

Car myCar = new Car();
int hp = myCar.[3]();

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

AgetHorsepower

Bhorsepower

DstartEngine

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method names like 'startEngine' instead of 'getHorsepower'.

Using incorrect attribute names.

The method name is 'getHorsepower'. It returns the 'horsepower' attribute of the engine. We call the method on the car object to get the horsepower value.