157 interview questions on Java for developers (2025)

32 votes2968 runs

Pierreat Sep 19, 2022

16 votes3431 runs

control flow

Thomas De verdièreat Dec 16, 2021

14 votes1589 runs

13 votes3436 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

13 votes3314 runs0 comment

Thomas De verdièreat Jan 4, 2022

13 votes3273 runs0 comment

Thomas De verdièreat Dec 16, 2021

13 votes2876 runs

Pierreat Sep 19, 2022

12 votes3473 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3369 runs0 comment

Thomas De verdièreat Jan 4, 2022

11 votes3433 runs

serialization

Thomas De verdièreat Dec 2, 2021

11 votes3320 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

11 votes2754 runs

concatenation

Pierreat Jan 4, 2022

9 votes3408 runs0 comment

Thomas De verdièreat Jan 4, 2022

9 votes3253 runs0 comment

Thomas De verdièreat Jan 4, 2022

9 votes2789 runs0 comment

Pierreat Jan 4, 2022

8 votes3275 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3220 runs2 comments

Thomas De verdièreat Jan 4, 2022

7 votes3411 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3296 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3246 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?

Add elements to an ArrayList in Java

What is the classpath for?

What does the following code show?

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?