150 interview questions on Java for developers (2025)

28 votes2778 runs

Pierreat Sep 19, 2022

16 votes3299 runs

control flow

Thomas De verdièreat Dec 16, 2021

13 votes1386 runs

12 votes3300 runs1 comment

serialization

Thomas De verdièreat Jan 4, 2022

12 votes3251 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3190 runs0 comment

Thomas De verdièreat Jan 4, 2022

12 votes3142 runs0 comment

Thomas De verdièreat Dec 16, 2021

12 votes2691 runs

Pierreat Sep 19, 2022

11 votes3198 runs0 comment

design pattern

Thomas De verdièreat Jan 4, 2022

11 votes2588 runs

concatenation

Pierreat Jan 4, 2022

10 votes3351 runs0 comment

Thomas De verdièreat Jan 4, 2022

10 votes3300 runs

serialization

Thomas De verdièreat Dec 2, 2021

9 votes3130 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3277 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes3169 runs0 comment

Thomas De verdièreat Jan 4, 2022

8 votes2602 runs0 comment

Pierreat Jan 4, 2022

7 votes3280 runs0 comment

Thomas De verdièreat Dec 16, 2021

7 votes3174 runs1 comment

Thomas De verdièreat Jan 4, 2022

7 votes3129 runs0 comment

design patterns

Thomas De verdièreat Jan 4, 2022

7 votes2635 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?

How to concatenate two strings of characters in Java?

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?

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?