Java vs Scala - How Do They Differ?

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Java vs Scala - How Do They Differ?

Sangeeta Gulia
Last updated on November 26, 2022

    With the availability of a bunch of popular programming languages for development, Java and Scala have managed to gain popularity in the IT industry. Providing a wide variety of application areas and a strong feature set, these languages help developers to build robust and scalable applications. `

    Java is relatively older, while Scala is newer and was initially developed to address the shortcomings of Java. Both these languages are high-level languages and run on the Java Virtual Machine (JVM). Particularly, Scala was designed to be more compact so that developers can accomplish tasks with fewer lines of code than Java.

    Both Java and Scala have their set of applications or use cases. So let us explore how these two languages differ from each other.

    In this blog post, we shall shed light on the similarities and differences between Java and Scala. Also, we shall walk you through the features, advantages, and disadvantages of Java and Scala.

    So, let us get started without further ado!

    What is Java?

    Java is a general-purpose, high-level, object-oriented, multithreaded, and easy-to-learn programming language. It was designed with the intent to let the programmers write once and run anywhere. This means programmers can write and compile a Java program on one machine and run it on any other Java-enabled machine without the need to recompile. A Java program is first compiled into bytecode. This bytecode is capable of running on any machine having JVM installed.

    There is a wide range of applications of Java. It is ideal for developing gaming applications, web-based applications, desktop applications, mobile applications, web servers, big data applications, enterprise applications, and embedded systems.

    History

    James Gosling first released Java in 1995 as a product of Sun Microsystems. Initially, he named the language Oak after an oak tree, later renamed it Green, and finally decided to go with the name Java, which he named after the type of coffee in Indonesia.

    In 1996, Sun Microsystems released the first implementation of Java, i.e., Java 1.0. Later in 2009, Oracle acquired Sun Microsystems, and that’s why the language, its JRE, and JDK now belong to Oracle. At the time of writing this article, the latest stable release of Java was Java 19, released in September 2022.

    Features

    The following are some remarkable features of Java:

    • Object-Oriented: As Java is an object-oriented language , everything in Java is treated as an object. So, when you develop an application in Java, it means that you organize it as a combination of different types of objects that include both data and behavior.
    • Portable: Java is portable because you can carry the Java bytecode to any machine having JVM installed.
    • Platform-Independent: You can execute Java code on any Java-enabled platform. A Java compiler compiles Java code into bytecode, and you can execute that bytecode on any other machine without recompiling it.
    • Multithreaded: By defining multiple threads in Java, it is possible to execute multiple tasks concurrently. Another advantage of multithreading is it does not occupy memory space for each thread; rather, all threads of a process share the same memory space.
    • Dynamic: As Java is dynamic, it supports dynamic loading of classes, i.e., loading a class whenever it is needed.

    Advantages

    The following are the major advantages of Java:

    • Easy to understand and code.
    • It is secure since it eliminates the concept of pointers.
    • Java is platform-independent.
    • Java supports backward compatibility.
    • It has massive community support.

    Disadvantages

    Some significant downsides of Java are as follows:

    • It uses a traditional way to manage multithreading.
    • Java provides automatic garbage collection that cannot be controlled by the programmer. It doesn't provide the methods like delete() and free() to free up memory.
    • The GUI builder in Java is poor and is not useful for building complex UIs.

    What is Scala?

    Scala is a strong statically-typed programming language that combines the features of object-oriented as well as a functional programming language . Scala language got its name from the combination of two words: “Scalable” and “Language,” which explains that it can scale according to user requirements.

    Scala can be used to develop different types of applications, as follows:

    • Big data applications that require data processing and distributed computing.
    • Web applications with the help of Play Framework, Akka HTTP, etc.
    • Multithreaded applications with the help of Akka.

    History

    Scala was first internally released at the end of 2003 and publicly released in 2004. Martin Odersky first started designing Scala in 2001. He was inspired by the Funnel programming language that combined functional programming and Petri nets .

    March 2006 witnessed the release of the second version of Scala, Scala 2.0. The latest and stable version of Scala is 3.2.0, released in September 2022.

    Features

    Here are the silent features of Scala:

    • Type Inference: Scala does not require you to define the data type and function return type explicitly. The language itself is so smart that it interprets the type of data.
    • Singleton Objects: Scala does not have static variables or methods. It only uses a Singleton object, which is the class with only one object.
    • Immutability: It follows the concept of immutability. Variables you declare once are immutable by default, i.e., you cannot change their values. Immutability helps to achieve concurrency, which becomes easy to manage data.
    • Lazy Computation: Scala has lazy computation by default, i.e., it evaluates expressions only when needed. You can use the lazy keyword to declare a lazy variable.
    • Case Classes and Pattern Matching: Case classes are regular classes that are immutable by default. They are decomposable through pattern matching.
    • String Interpolation: Scala 2.10.0 has introduced a feature for creating strings from your data called string interpolation. There are three string interpolation methods: s, f, and raw.

    Advantages

    Here are some worth-mentioning advantages of Scala:

    • Scala has better support for immutability.
    • Everything is a value: Scala lets if blocks, for-yield loops, and code in braces return a value. This is very elegant in many situations. A very small plus is that this eliminates the need for a separate ternary operator.
    • As Scala is pure object-oriented, it does not have the concept of the static keyword like Java. Instead, it has singleton objects.
    • Scala supports some advanced features directly built into the language, such as Currying, Closures, Higher-order functions, pattern matching, Higher Kinded Types, Monads, and implicit params.
    • The language comes with Tuples built-in.
    • It supports object unpacking with the help of extractor objects.
    • Some keywords and syntactic sugars are optional to use, like the return keyword and semicolon, which gives you ease while coding.
    • Async and non-blocking code are very easy to write with Scala Futures.

    Disadvantages

    The following are a few major drawbacks of Scala:

    • The language has a steep learning curve for beginners.
    • Scala does not provide strong backward compatibility as compared to Java.
    • It is not as well established as Java in the market since it was invented later. Overall, Java is mature and has better community support.

    Java vs Scala - A Head-to-Head Comparison

    As per the stack overflow developers survey , we can understand the popularity of both Java and Scala in terms of their usage and in terms of developers’ pay scale. Support communities for both languages are very strong.

    Before we move on to discussing the differences between Java and Scala, let us first understand the similarities between the two:

    Similarities Between Java and Scala

    • Both languages are statically typed languages, which means that type checking is done at the compile type rather than at the run time. This helps to identify a few errors in the compilation phase itself.
    • Both languages are compiled to bytecode by their individual compiler and run on JVM. In other words, the code is compiled to .class files, packaged in JAR files, and runs on the JVM.
    • Both languages have support for lambdas and higher-order functions
    • They can both be used with IDEs like IntelliJ IDEA and Microsoft VS Code
    • Projects can be built with build tools like Sbt, Gradle, Ant, and Maven.
    • You can call Scala from Java and Java from scala. They are easily interoperable.

    Java vs Scala

    Let us now highlight the differences between Java and Scala:

    Java

    Scala

    It is an object-oriented programming language.

    Scala is a functional as well as a pure object-oriented programming language. There is no concept of primitive data types. Data types are also classes in Scala, which make it pure object-oriented.

    Java code is lengthy and hence less complex and more readable.

    Scala code is concise and hence a little complex to understand sometimes for beginners.

    The Java language supports backward compatibility between its different versions.

    It supports limited backward compatibility between versions.

    It has a ‘static’ keyword to create static classes and methods.

    In Scala, there is no concept of static. However, you can create singleton objects to achieve similar results.

    Java has variables that are mutable by default. This means that after you create a variable, it is not possible to alter its state/value.

    Scala supports immutability. You can create both types of variables, mutable as well as immutable. The default nature of a variable will be immutable.

    Java does not support lazy evaluation.

    This language supports lazy evaluation, which helps to evaluate the value of an expression only when it will be needed. This helps to reduce redundant evaluation.

    It has come up with pattern matching in the new releases. However, it is not that mature.

    Scala supports pattern matching and case classes.

    Popular Java frameworks include Spring, Grail, etc.

    Some popular Scala frameworks include Play, Akka, Lift, etc.

    It uses a conventional thread-based model for achieving concurrency.

    Scala uses Akka or Futures to achieve concurrency. These are wrappers on threads and hence are easier to write in a crisp manner.

    Java has the concept of interfaces.

    This language uses traits to achieve the same result that you get using the interfaces in Java.

    Scala code can also be converted to Java code using asJava. Converting Java code to Scala code is a little trickier.

    Scala code is interoperable with Java. You can use Java libraries in your scala code but be careful to handle NullPointer exceptions and mutability etc.

    Some of the tech giants that use Java are:

    • Apple
    • Google
    • Amazon
    • Facebook
    • Youtube

    Some of the tech giants that use Scala are:

    • Twitter
    • Netflix
    • Apache Spark
    • AirBnB
      LinkedIn

    How Does Scala work with Java?

    • Scala program is first compiled to Java bytecode.
    • Tools like javap (Java class file disassembler, which comes as part of JRE) can be used to disassemble bytecodes generated by the Scala compiler.
    • Scala code is converted to Java code so that Scala can easily integrate with Java.

    How do Java and Scala differ syntactically?

    To start understanding the details about these languages, you can use any IDE that you are familiar with, such as Eclipse, or IntelliJ IDEA. I prefer using the IntelliJ IDEA.

    • Writing main method:

    Java

    Scala

    public class Test {
    
    public static void main(String args[]) {
    
    System.out.println("Hello World");
    
    }
    
    }

    public class Test {
    
    public static void main(String args[]) {
    
    System.out.println("Hello World");
    
    }
    
    }

    OR

    object Test extends App {
    
    println("Hello World")
    
    }

    • Loops

    Java

    Scala

    import java.util.ArrayList;
    
    import java.util.List;
    
    
    public class Test {
    
     
    public static void main(String args[]) {
    
    List<String> listExample = new ArrayList<String>();
    
    listExample.add("Cat");
    
    listExample.add("Dog");
    
    listExample.add("Cow");
    
    listExample.add("Rabbit");
    
    //Iterating the List element using for-each loop
    
    for (String element : listExample)
    
    System.out.println(element);
    
    }
    
    }

    object Test {
    
    def main(args: Array[String]): Unit = {
    
    val listExample = List("Cat", "Dog", "Cow", "Rabbit")
    
    for (element <- listExample) {
    
    println(element)
    
    }
    
    }
    
    }

    • Classes

    Java

    Scala

    class Laptop {
    
    public String canType() {
    
    return "My laptop helps me type";
    
    }
    
    
    public String canProcessData() {
    
    return "Give me data and algorithm and i will process for you";
    
    }
    
    }
    
     
    public class Test {
    
     
    public static void main(String args[]) {
    
    Laptop laptopObject = new Laptop();
    
    System.out.println(laptopObject.canType());
    
    System.out.println(laptopObject.canProcessData());
    
    }
    
    }

    class Laptop {
    
    def canType(): String = "My laptop helps me type"
    
    
    def canProcessData(): String = "Give me data and algorithm and i will process for you"
    
    }
    
     
    object Test {
    
    def main(args: Array[String]): Unit = {
    
    val laptopObject = new Laptop()
    
    println(laptopObject.canType())
    
    println(laptopObject.canProcessData())
    
    }
    
    }




    The above example explains how we can create classes and their methods and objects and access their methods.

    • Return keyword and use of the semicolon is optional in Scala while it’s mandatory in Java

    We can use the same above example to see that while returning a result from a method, the use of the keyword “return” is mandatory while this is not needed in Scala. Also, you can notice that a semicolon is not needed in Scala after every statement, while it is required in Java. For semicolons, it holds true for imports also.

    • Nested Methods

    Java

    Scala

    Java does not support direct nested methods. Although you can achieve this by defining a class inside a method and then you can define a method in that local nested class.

    def printList(list: List[Integer]) = {
    
    def recursiveListIterator(list:List[Integer]): Unit = {
    
    list match {
    
    case Nil => println("List is empty")
    
    case head :: Nil => print(head)
    
    case head :: tail => print(head)
    
    recursiveListIterator(tail)
    
    }
    
    }
    
     recursiveListIterator(list)
    
    }
    
    
    printList(List(2,3,4))
    
    printList(List())
    
    println(List(8))

    • Defining Imports

    Java

    Scala

    How to define import for entire package:

    import java.security.*;


    How to import a specific class:

    import java.util.ArrayList;

    How to define import for entire package:

    import java.security._


    How to import a specific class:

    import java.util.ArrayList;

    • Working with Strings

    Java

    Scala

    class Test {
    
    
    public static void main(String args[]) {
    
    String str = "Compare me";
    
    String str2 = "Compare me";
    
    
    String str3 = "Compare me again";
    
    String str4 = null;
    
    String str5 = "compare me";
    
    System.out.println(str == str2); // true
    
    System.out.println(str3 == str4); //false
    
    System.out.println(str == str5); // false
    
    // if strings are case-sensitive
    
    // they will be considered different
    
    }
    
    }

    object Test {
    
    def main(args: Array[String]): Unit = {
    
    val str: String = "Compare me"
    
    val str2: String = "Compare me"
    
    val str3: String = "Compare me again"
    
    val str4 = null
    
    val str5 = "compare me"
    
    System.out.println(str eq str2) // true
    
    
    System.out.println(str3 eq str4) //false
    
     
    System.out.println(str eq str5) // false
    
     
    // if strings are case-sensitive
    
    // they will be considered different
    
    }

    Note: Scala String is an alias to Java String. This definition can be found in the Predef.scala package which is imported by default in all Scala programs. A few other details from the code comments:

    /** The `String` type in Scala has all the methods of the underlying

    [[java.lang.String]], of which it is just an alias.

    In addition, extension methods in [[scala.collection.StringOps]] are added implicitly through the conversion [[augmentString]].

    */

    type String = java.lang.String
    • Alternative to the eq method we can also use “==” for string comparison.
    • Inheritance

    Java

    Scala

    interface Shape {
    
    double area();
    
    }
    
    
    class Rectangle implements Shape {
    
    int length=0;
    
    int breadth=0;
    
     
    Rectangle(int length, int breadth) {
    
    this.length = length;
    
    this.breadth= breadth;
    
    }
    
     
    @Override
    
    public double area() {
    
    return length*breadth;
    
    }
    
    }
    
     
    public class InheritanceExample {
    
    public static void main(String args[]) {
    
    Rectangle r = new Rectangle(2,3);
    
    System.out.println(r.area());
    
    }
    
    }

    Note: In Java implements keyword is used for inheritance using interfaces and extends keyword is used for classes.

    trait Shape {
    
    def area: Double
    
    }
    
    
    class Rectangle(val length: Int, val breadth: Int) extends Shape {
    
    override def area: Double = length * breadth
    
    }
    
     
    object InheritanceExample {
    
    def main(args: Array[String]): Unit = {
    
    val r = new Rectangle(2, 3)
    
    println(r.area)
    
    }
    
    }










    Note: In Scala, we can only extend one class, and then we can mixin trait with the below syntax:

    Class <DerivedClass> extends <BaseClass> with <Traits>

    • Default packages Imported

    Java

    Scala

    java.lang.*;

    import java.lang._

    import scala._

    import Predef._

    What Java Shortcomings Does Scala Overcome?

    • Scala improved upon the collection framework.
    • It introduced the Option type to overcome issues related to null pointer exceptions. Although in later versions Java also came up with optional.
    • It focused more on immutability and provided the default nature of lots of collections as immutable. Although a mutable version is also available for use.
    • Both languages are getting updated and advanced with the release of newer versions, so the comparison is based on who launched what earlier.

    Conclusion

    This was all about the differences between Java and Scala. Each language has its own features, advantages, and disadvantages. The choice between Java and Scala entirely depends on individuals’ preferences and project requirements. So, make sure to first analyze your project requirements and then choose the suitable language.

    Happy reading, happy learning!

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    FAQs


    Though Java is a popular language, it is not compact and concise. Even if you wish to accomplish a small task, you will need to write lengthy code in Java. To overcome the shortcomings of Java, there was the inception of the Scala language. Scala has a compact and concise syntax. It has the ability to replace the verbose code of Java with just fewer lines of code.

    It is always recommended to learn Java first but not mandatorily. When you learn Java first, you will have the basics of object-oriented programming and many other programming concepts. Basically, before learning Scala, it is good to have knowledge of any functional programming language.

    When it comes to the learning curve, Java is a clear winner. It has a low learning curve as its syntax is elegant and easy to understand. Scala, on the flip side, is compact, and hence, beginners find its syntax complex and tricky to understand.

    Yes, you can learn Scala even if you are not familiar with Java. However, it is advisable to have familiarity with any functional programming language to learn Scala.

    According to Glassdoor, the median salary of a Scala developer in India is INR 7.3 lakhs/year, whereas it is $95K per year in the United States.

    The average salary of a Java developer in India is INR 4.5 lakhs per annum, while it is $99K per year in the United States, according to Glassdoor.

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