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 is casting?</p>
    </div>
    <div class="ans">
        <p><span class="hi-yl-b">Type casting or simply casting is used to convert an object or variable of one type into another.</span> There are two types of casting:</p>

<ul>
<li><p>Casting primitives</li>
<li><p>Casting objects</p></li>
</ul></div>
</div>


<div class="card">
   # Question # 2
    <div class="qtn">
        <p>Explain how casting of primitive types works in Java.</p>
    </div>
    <div class="ans">
        <p><span class="hi-yl">When casting between primitive types if the destination can hold a larger value than the source, the cast is implicitly done by the compiler without complaining. There's no loss of information or precision when the destination can comfortably hold the value in the source. This is called a <i>widening cast</i></span>. For example:</p>

<ul>
<li><p>int to double</p></li>
<li><p>char to int</p></li>
<li><p>float to double</p></li>
</ul>
## Implicit casts
<b>

```java
      int i = 5;
      char c = 'a';
      float f = 5.5f;

      // int to double
      double d = i;

      // char to int
      i = c;

      // float to double
      d = f;
```
</b>

<p><span class="hi-yl">Casting when the destination can hold a smaller value than the source requires an explicit cast otherwise the compiler will complain. Such casts are called narrowing casts.</span> There are rules described in the JLS how such narrowing casts take place. Narrowing casts can possibly lose precision and sometimes give unexpected results if one isn't familiar with the rules. For example:</p>
## Explicit casts
<b>

```java
        // i will contain Integer.MAX_VALUE after the cast
        int i = (int) (Integer.MAX_VALUE * 2.0d);
        
        // b will contain the value 100
        byte b = (byte) (100d);

        // b will print -24
        byte b = (byte) (1000d);
```
</b>
</div>
</div>


<div>
   # Question # 1
    <div>
        <p>What is casting?</p>
    </div>
    <div>
        <p><span>Type casting or simply casting is used to convert an object or variable of one type into another.</span> There are two types of casting:</p>

<ul>
<li><p>Casting primitives</li>
<li><p>Casting objects</p></li>
</ul></div>
</div>


<div>
   # Question # 2
    <div>
        <p>Explain how casting of primitive types works in Java.</p>
    </div>
    <div>
        <p><span>When casting between primitive types if the destination can hold a larger value than the source, the cast is implicitly done by the compiler without complaining. There's no loss of information or precision when the destination can comfortably hold the value in the source. This is called a <i>widening cast</i></span>. For example:</p>

<ul>
<li><p>int to double</p></li>
<li><p>char to int</p></li>
<li><p>float to double</p></li>
</ul>
## Implicit casts
<b>

```java
      int i = 5;
      char c = 'a';
      float f = 5.5f;

      // int to double
      double d = i;

      // char to int
      i = c;

      // float to double
      d = f;
```
</b>

<p><span>Casting when the destination can hold a smaller value than the source requires an explicit cast otherwise the compiler will complain. Such casts are called narrowing casts.</span> There are rules described in the JLS how such narrowing casts take place. Narrowing casts can possibly lose precision and sometimes give unexpected results if one isn't familiar with the rules. For example:</p>
## Explicit casts
<b>

```java
        // i will contain Integer.MAX_VALUE after the cast
        int i = (int) (Integer.MAX_VALUE * 2.0d);
        
        // b will contain the value 100
        byte b = (byte) (100d);

        // b will print -24
        byte b = (byte) (1000d);
```
</b>
</div>
</div>


This lesson includes interview questions on casting in Java.

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

Casting

Question # 1

Question # 2