149 interview questions on Java for developers (2025)

26 votes2650 runs

Pierreat Sep 19, 2022

16 votes3205 runs0 comment

control flow

Thomas De verdièreat Dec 16, 2021

13 votes1257 runs

12 votes3198 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

12 votes3161 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3058 runs0 comment

Thomas De verdièreat Dec 16, 2021

11 votes3117 runs0 comment

Thomas De verdièreat Jan 4, 2022

11 votes3115 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

11 votes2563 runs

Pierreat Sep 19, 2022

10 votes3258 runs0 comment

Thomas De verdièreat Jan 4, 2022

10 votes2478 runs

concatenation

Pierreat Jan 4, 2022

9 votes3047 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3199 runs

serialization

Thomas De verdièreat Dec 2, 2021

8 votes3192 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3089 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes2480 runs0 comment

Pierreat Jan 4, 2022

7 votes3179 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3075 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3060 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

7 votes2523 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

How many instance of Integer cannot be freed from memory?

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

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

How should a package be named in Java?

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

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?

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

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?