150 interview questions on Java for developers (2025)

28 votes2768 runs

Pierreat Sep 19, 2022

16 votes3293 runs

control flow

Thomas De verdièreat Dec 16, 2021

13 votes1375 runs

12 votes3289 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

12 votes3242 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3185 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3131 runs0 comment

Thomas De verdièreat Dec 16, 2021

12 votes2679 runs

Pierreat Sep 19, 2022

11 votes3194 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

10 votes3342 runs0 comment

Thomas De verdièreat Jan 4, 2022

10 votes3290 runs

serialization

Thomas De verdièreat Dec 2, 2021

10 votes2579 runs

concatenation

Pierreat Jan 4, 2022

9 votes3121 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3268 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3160 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes2586 runs0 comment

Pierreat Jan 4, 2022

7 votes3271 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3165 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3123 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

7 votes2627 runs0 comment

Pierreat Sep 19, 2022

150 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 150 corrected questions. Beginner, Intermediate or Expert level.

150 interview questions on Javafor developers (2025)

Test your technical skills before an interview of Java with 150 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?