149 interview questions on Java for developers (2025)

28 votes2738 runs

Pierreat Sep 19, 2022

16 votes3275 runs

control flow

Thomas De verdièreat Dec 16, 2021

13 votes1345 runs

12 votes3268 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

12 votes3220 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3173 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3115 runs0 comment

Thomas De verdièreat Dec 16, 2021

12 votes2651 runs

Pierreat Sep 19, 2022

11 votes3174 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

10 votes3324 runs0 comment

Thomas De verdièreat Jan 4, 2022

10 votes3267 runs

serialization

Thomas De verdièreat Dec 2, 2021

10 votes2556 runs

concatenation

Pierreat Jan 4, 2022

9 votes3108 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3247 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3143 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes2561 runs0 comment

Pierreat Jan 4, 2022

7 votes3249 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3146 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3110 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

7 votes2603 runs0 comment

Pierreat Sep 19, 2022

149 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 149 corrected questions. Beginner, Intermediate or Expert level.

149 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 149 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

A monitor in Java

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?

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

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

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

How to concatenate two strings of characters in Java?

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

A “synchronized” method

What is the classpath for?

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?

Are arrays primitives types in Java?