149 interview questions on Java for developers (2025)

26 votes2642 runs

Pierreat Sep 19, 2022

16 votes3197 runs0 comment

control flow

Thomas De verdièreat Dec 16, 2021

13 votes1249 runs

12 votes3154 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3052 runs0 comment

Thomas De verdièreat Dec 16, 2021

11 votes3194 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

11 votes3111 runs0 comment

Thomas De verdièreat Jan 4, 2022

11 votes3106 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

11 votes2554 runs

Pierreat Sep 19, 2022

10 votes3249 runs0 comment

Thomas De verdièreat Jan 4, 2022

10 votes2471 runs

concatenation

Pierreat Jan 4, 2022

9 votes3042 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3191 runs

serialization

Thomas De verdièreat Dec 2, 2021

8 votes3184 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3081 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes2472 runs0 comment

Pierreat Jan 4, 2022

7 votes3173 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3068 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3051 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

7 votes2515 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?

A monitor in Java

How many instance of Integer cannot be freed from memory?

Serialization can be customized with the Externalizable interface

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?