The ultimate guide to Java interviews with 300+ real-world questions and answers. Get interview-ready in just a few hours with strategies developed by FAANG engineers.

It’s very common to have interviews testing your knowledge of a programming language you claim to be an expert in.

If you've got an interview coming up on Java soon and need to get up to speed, this is the ideal course for you. You'll refresh your memory on everything from the basics to more advanced functionality you’re likely to be asked about. Even if you're using Java every day, you may not have been exposed to parts of it in some time, so it's always useful to make sure you're updated.

This course features more than 300 of the most commonly asked core Java interview questions that you're likely to face as an experienced software engineer. You'll get to explore questions by topic, as well as see detailed answers for each one, and plenty of live code examples where relevant. Get started today.

The Java Interview Handbook: 300+ Interview Questions


<div class="card">
   # Question # 1
    <div class="qtn">
        <p>What are some of the differences between a process and a thread?</p>
    </div>
    <div class="ans">
<p>Some of the differences between a process and a thread are:</p>
        <ul>
<li><p>A process can have many threads, whereas a thread can belong to only one process.</p></li>
<li><p>A thread is lightweight than a process and uses less resources than a process.</p></li>
<li><p>A thread has some state private to itself but threads of a process can share the resources allocated to the process including memory address space.</p></li>
</ul></div>
</div>

<div class="card">
   # Question # 2
    <div class="qtn">
        <p>Can you list some of the problems with using threads?</p>
    </div>
    <div class="ans">
        <p>Threads if used without thought can sometimes lead to performance degradation for the following reasons:</p>
<ul>
  <li><p><b><i>Usually hard to find bugs</b></i>, some that may only rear head in production environments (think race conditions)</p></li>
  <li><p><b><i>Higher cost of code maintenance</b></i> since the code inherently becomes harder to reason about</p></li>
  <li><p><b><i>Increased utilization of system resources</b></i>. Creation of each thread consumes additional memory, CPU cycles for book-keeping and waste of time in context switches.</p></li>
<li><p><b><i>Too many threads</i></b> can decrease program performance due to increased competition to acquire locks (lock contention).</p></li>  
</ul>
</div>
</div>



<div>
   # Question # 1
    <div>
        <p>What are some of the differences between a process and a thread?</p>
    </div>
    <div>
<p>Some of the differences between a process and a thread are:</p>
        <ul>
<li><p>A process can have many threads, whereas a thread can belong to only one process.</p></li>
<li><p>A thread is lightweight than a process and uses less resources than a process.</p></li>
<li><p>A thread has some state private to itself but threads of a process can share the resources allocated to the process including memory address space.</p></li>
</ul></div>
</div>

<div>
   # Question # 2
    <div>
        <p>Can you list some of the problems with using threads?</p>
    </div>
    <div>
        <p>Threads if used without thought can sometimes lead to performance degradation for the following reasons:</p>
<ul>
  <li><p><b><i>Usually hard to find bugs</b></i>, some that may only rear head in production environments (think race conditions)</p></li>
  <li><p><b><i>Higher cost of code maintenance</b></i> since the code inherently becomes harder to reason about</p></li>
  <li><p><b><i>Increased utilization of system resources</b></i>. Creation of each thread consumes additional memory, CPU cycles for book-keeping and waste of time in context switches.</p></li>
<li><p><b><i>Too many threads</i></b> can decrease program performance due to increased competition to acquire locks (lock contention).</p></li>  
</ul>
</div>
</div>


This lesson introduces the fundamentals of concurrency.

Java Ecosystem

Methods

Classes

Interfaces

Inheritance

Lambda Expressions

Generics

Multi-Threading

Memory Management

Collections

Exceptions

Reflection

Serialization

Miscellaneous Topics

Java in Practice

Patterns

The End

Fundamentals

Question # 1

Question # 2