157 interview questions on Java for developers (2025)

32 votes2957 runs

Pierreat Sep 19, 2022

16 votes3426 runs

control flow

Thomas De verdièreat Dec 16, 2021

14 votes1576 runs

13 votes3431 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

13 votes3309 runs0 comment

Thomas De verdièreat Jan 4, 2022

13 votes3270 runs0 comment

Thomas De verdièreat Dec 16, 2021

13 votes2865 runs

Pierreat Sep 19, 2022

12 votes3468 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3367 runs0 comment

Thomas De verdièreat Jan 4, 2022

11 votes3430 runs

serialization

Thomas De verdièreat Dec 2, 2021

11 votes3315 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

11 votes2744 runs

concatenation

Pierreat Jan 4, 2022

9 votes3405 runs0 comment

Thomas De verdièreat Jan 4, 2022

9 votes3250 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3273 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3215 runs2 comments

Thomas De verdièreat Jan 4, 2022

8 votes2778 runs0 comment

Pierreat Jan 4, 2022

7 votes3409 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3294 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3243 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

157 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 157 corrected questions. Beginner, Intermediate or Expert level.

157 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 157 corrected questions. Beginner, Intermediate or Expert level.

Write a Java program that prints 'welovedev'.

How many times is the condition `(a++ < 15)` evaluated in the following code? ```java int a = 3; while (a++ < 15) { if ((a++ % 5) == 0) break; } ```

What is the difference between an interface and an abstract class in Java?

Serialization can be customized with the Externalizable interface

What does the final keyword mean in front of a method in Java?

How many instance of Integer cannot be freed from memory?

How should a package be named in Java?

A Customer class has the com.company.model package.

A monitor in Java

What is the error message when you try to serialize a class that does not implement Serializable?

What "design pattern" makes it possible to offer a means of treating the elements of a tree without worrying about the course?

How to concatenate two strings of characters in Java?

A “synchronized” method

Which of these classes is the most suitable for composing a character string from several elements concatenated to each other?

What is the classpath for?

What does the following code show?

Add elements to an ArrayList in Java

Write a finalizer in Java.

What is the superclass of Integer, Long, Byte, BigDecimal and Short in Java?

What design pattern will you use to dynamically add capabilities to an object in Java?