Autoboxing in Java - Practice Problems & Coding Challenges

trophy

Challenge - 5 Problems

💻 code output

intermediate

What is the output of autoboxing with == operator?

Consider the following Java code snippet. What will be printed when it runs?

Java

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

A Runtime exception

B true

C Compilation error

D false

💻 code output

intermediate

What is the output when adding Integer and int?

What will the following Java code print?

Java

Integer x = 5;
int y = 10;
System.out.println(x + y);

A 15.0

B 15

C Compilation error

D NullPointerException

🔧 debug

advanced

Why does this code throw NullPointerException?

Examine the code below. Why does it throw a NullPointerException at runtime?

Java

Integer a = null;
int b = a;
System.out.println(b);

A Because Integer cannot be assigned to int

B Because variable a is not initialized

C Because unboxing null Integer to int causes NullPointerException

D Because printing int b is invalid

🧠 conceptual

advanced

How does autoboxing affect performance?

Which statement best describes the performance impact of autoboxing in Java?

A Autoboxing can cause performance overhead due to object creation and garbage collection

B Autoboxing always improves performance by caching objects

C Autoboxing has no impact on performance

D Autoboxing reduces memory usage by using primitives only

💻 code output

expert

What is the output of this tricky autoboxing and caching code?

Analyze the code below and select the output it produces.

Java

Integer i1 = 127;
Integer i2 = 127;
Integer i3 = 128;
Integer i4 = 128;
System.out.println(i1 == i2);
System.out.println(i3 == i4);

A

true
false

B

false
false

C

true
true

D

false
true