Object lifecycle in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new object of class Car.

Java

Car myCar = new [1]();

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AObject

Bcar

CCar

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase class name like 'car' causes errors.

Using unrelated class names like 'Vehicle' or 'Object'.

In Java, to create a new object, you use the class name with new. Here, Car is the class name.

2fill in blank

medium

Complete the code to call the constructor of class Person with a name parameter.

Java

Person p = new Person([1]);

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A"Alice"

B25

Ctrue

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a number instead of a string.

Forgetting quotes around the name.

The constructor expects a name, which is a string. Strings in Java are written inside double quotes.

3fill in blank

hard

Fix the error in the code to properly destroy an object reference.

Java

myObject = [1];

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Adelete

Bnull

Cremove

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'delete' which is not valid in Java.

Using 'remove' or 'void' which are invalid here.

In Java, to remove a reference to an object so it can be garbage collected, assign null to the variable.

4fill in blank

hard

Fill both blanks to create an object and call its method.

Java

Car [1] = new [2]();
[1].startEngine();

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AmyCar

BCar

Cengine

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for variable and constructor.

Using invalid variable names.

First, we name the object myCar. Then, we create a new Car object. Finally, we call the method on myCar.

5fill in blank

hard

Fill all three blanks to create a Person object, assign it to a variable, and call a method.

Java

Person [1] = new [2]([3]);
[1].sayHello();

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Aperson1

BPerson

C"Bob"

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching variable and constructor names.

Passing a parameter without quotes.

We name the variable person1, create a new Person with the name "Bob", then call sayHello() on person1.