Why wrapper classes are used in Java - Challenge Your Understanding

trophy

Challenge - 5 Problems

🧠 conceptual

intermediate

Purpose of Wrapper Classes in Java

Why are wrapper classes used in Java?

A To replace all primitive types with classes

B To allow primitive data types to be used as objects

C To improve the speed of primitive operations

D To create new primitive data types

💻 code output

intermediate

Output of Autoboxing Example

What is the output of this Java code?

Java

Integer a = 1000;
Integer b = 1000;
System.out.println(a == b);

A true

B Compilation error

C false

D Runtime exception

💻 code output

advanced

Result of Using Wrapper Class in Collection

What will be the output of this Java code snippet?

Java

import java.util.List;
import java.util.ArrayList;

List<Integer> list = new ArrayList<>();
list.add(10);
list.add(null);
System.out.println(list.get(1) == null);

A true

B false

C NullPointerException

D Compilation error

🧠 conceptual

advanced

Why Wrapper Classes are Needed for Generics

Why do Java generics require wrapper classes instead of primitive types?

A Because wrapper classes have more methods than primitives

B Because wrapper classes are faster than primitives

C Because primitives cannot be stored in variables

D Because generics work only with objects, not primitives

🔧 debug

expert

Identify the Error with Wrapper Class Usage

What error will this Java code produce?

Java

int x = null;
Integer y = null;
System.out.println(x + y);

A Compilation error: incompatible types

B NullPointerException at runtime

C Output: 0

D No error, prints 'null'