Unboxing in Java - Practice Problems & Coding Challenges

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Challenge - 5 Problems

💻 code output

intermediate

What is the output of this unboxing example?

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

Java

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

A true

B Runtime exception

C Compilation error

D false

💻 code output

intermediate

What is the output when comparing Integer objects with ==?

What will this Java code print?

Java

Integer x = 127;
Integer y = 127;
System.out.println(x == y);
Integer m = 128;
Integer n = 128;
System.out.println(m == n);

A

false
false

B

true
true

C

true
false

D

false
true

🔧 debug

advanced

Identify the runtime error caused by unboxing

What error will this code produce when run?

Java

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

A NullPointerException

B Compilation error

C Prints 0

D No output, infinite loop

💻 code output

advanced

What is the output of this mixed boxing and unboxing code?

Analyze the output of this Java code snippet:

Java

Integer i = 10;
int j = 10;
System.out.println(i.equals(j));
System.out.println(i == j);

A

false
false

B

true
true

C

true
false

D

false
true

🧠 conceptual

expert

How many Integer objects are created in this code?

Consider this Java code snippet. How many distinct Integer objects are created during execution?

Java

Integer a = 100;
Integer b = 100;
Integer c = new Integer(100);
Integer d = Integer.valueOf(100);
Integer e = 200;
Integer f = 200;

A 4

B 5

C 3

D 6