how is python an interpreted language

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Python has become more popular than Java. Google Trends shows Python’s fame rose above Java in 2017:

The trend is likely caused because of Python’s great use for experimentation, and Java’s better use for production code. There is more experimentation than production code.

Java is a statically typed and compiled language, and Python is a dynamically typed and interpreted language. This single difference makes Java faster at runtime and easier to debug, but Python is easier to use and easier to read.

Python has gained popularity, in large part, due to its communicativity; people just grasp it easier. With it, the libraries for Python are immense, so a new programmer will not have to start from scratch. Java is old and still widely used, so it also has a lot of libraries and a community for support.

Now, let’s take a look at these in depth, including some code examples to illustrate the differences between Python and Java.

Python overview

Python was first released in 1991. It is an interpreted, high-level, general purpose programming language. It is Object-Oriented.

Designed by Guido van Rossum, Python actually has a design philosophy centered around code readability. The Python community will grade each other’s code based on how Pythonic the code is.

When to use Python

Python’s libraries allow a programmer to get started quickly. Rarely will they need to start from scratch. If a programmer wishes to jump into machine learning, there’s a library for that. If they wish to create a pretty chart, there’s a library for that. If they wish to have a progress bar shown in their CLI, there’s a library for that.

Generally, Python is the Lego of the programming languages; find a box with instructions on how to use it and get to work. There is little that needs to be started from scratch.

Because of its readability, Python is great for:

  1. New programmers
  2. Getting ideas down fast
  3. Sharing code with others

Java overview

Java is old. Java is a general-purpose programming language that utilizes classes and, like Python, is object-oriented.

Java was developed by James Gosling at Sun Microsystems, released in 1995 as a part of Sun Microsystem’s Java Platform. Java transformed the web experience from simple text pages to pages with video and animation.

When to use Java

Java is designed to run anywhere. It uses its Java Virtual Machine (JVM) to interpret compiled code. The JVM acts as its own interpreter and error detector.

With its ties to Sun Microsystems, Java was the most widely used server-side language. Though no longer the case, Java reigned for a long while and garnered a large community, so it continues to have a lot of support.

Programming in Java can be easy because Java has many libraries built on top of it, making it easy to find code already written for a specific purpose.

Who uses Python & Java?

Python is often used with new programmers or junior developers entering a data science role. The big machine learning libraries, TensorFlow and pyTorch, are both written in Python.

Python has excellent data processing libraries with Pandas and Dask, and good data visualization capabilities with packages such as Matplotlib and Seaborn.

Java is used a lot for web development. It is more common among senior-level programmers. It allows for asynchronous programming, and has a decent Natural Language Processing community.

Both languages can be used in API interactions and for machine learning. Java is better developed for building web applications. Python’s Flask library is still only able to build the basics to a Python-based UI but is great for creating a Python back-end with an API endpoint.

Python vs Java in code

Let’s see how Java and Python work differently.

Syntax

Because Python is an interpreted language, its syntax is more concise than Java, making getting started easier and testing programs on the fly quick and easy. You can enter lines right in the terminal, where Java needs to compile the whole program in order to run.

Type python and then 3+5 and the computer responds with 5.Copy

python

3+2
5

Consider doing this with Java. Java has no command line interpreter (CLI), so, to print 5 like we did above, we have to write a complete program and then compile it. Here is Print5.java:Copy

public class Print5 {

public static void main(String[] args) {
System.out.println("3+2=" + (Integer.toString(3+2)));
}
}

To compile it, type javac Print5.java and run it with java Print5.Copy

java Print5
3+2=5

With Java, we had to make a complete program to print 5. That includes a class and a main function, which tells Java where to start.

We can also have a main function with Python, which you usually do when you want to pass it arguments. It looks like this:Copy

def main():
print('3+2=', 3+2)if __name__== "__main__":
main()

Classes

Python code runs top to bottom—unless you tell it where to start. But you can also make classes, like possible with Java, like this:

Python ClassCopy

class Number:
def __init__(self, left, right):
self.left = left
self.right = rightnumber = Number(3, 2)print("3+2=", number.left + number.right)

The class, Number, has two member variables left and right. The default constructor is __init__. We instantiate the object by calling the constructor number = Number(3, 2). We can then refer to the variables in the class as number.left and number.right. Referring to variables directly like this is frowned upon in Java. Instead, getter and setter functions are used as shown below.

Here is how you would do that same thing In Java. As you can see it is wordy, which is the main complaint people have with Java. Below we explain some of this code.

Java Class with Getter and Setter functionsCopy

class PrintNumber {
int left;
int right;PrintNumber(int left, int right) {
this.left = left;
this.right = right;
}public int getleft() {
return left;
}
public int getRight() {
return right;
}
}public class Print5 {public static void main(String[] args) {
PrintNumber printNumber = new PrintNumber (3,2);
String sum = Integer.toString(printNumber.getleft()
+ printNumber.getRight() );
System.out.println("3+2=" + sum);
}
}

Python is gentle in its treatment of variables. For example, it can print dictionary objects automatically. With Java it is necessary to use a function that specifically prints a dictionary. Python also casts variables of one type to another to make it easy to print strings and integers.

On the other hand, Java has strict type checking. This helps avoid runtime errors. Below we declare an array of Strings called args.Copy

String[] args

You usually put each Java class in its own file. But here we put two classes in one file to make compiling and running the code simpler. We have:Copy

class PrintNumber {

int left;
int right;
}

That class has two member variables left and right. In Python, we did not need to declare them first. We just did that on-the-fly using the self object.

In most cases Java variables should be private, meaning you cannot refer to them directly outside of the class. Instead you use getter functions to retrieve their value. Like this.Copy

public int getleft() {
return left;
}

So, in the main function, we instantiate that class and retrieve its values:Copy

public int getleft() {
return left;
}public static void main(String[] args) {PrintNumber printNumber = new PrintNumber (3,2);
String sum = Integer.toString(printNumber.getleft()
+ printNumber.getRight() );

Where Python is gentle in its treatment of variables, Java is not.

For example, we cannot concatenate and print numbers and letters like “3+2=” + 3 + 2. So, we have to use the function above to convert each integer to a string Integer.toString(), and then print the concatenation of two strings.

Learn both Java & Python

Both programming languages are suitable for many people and have large communities behind them. Learning one does not mean you can’t learn the other—many programmers venture into multiple languages. And learning multiple can reinforce the understanding of programming languages altogether.

By many measures, Python is the simpler one to learn, and migrating to Java afterwards is possible.

Programming Languages are a fundamental part of computer science, they are fundamental tools in a programmer’s toolbox and crucial to almost every programming activity. Choosing between programming languages is often confusing, let alone choosing between the most popular ones.  Python and Java have been battling for the top position on the most popular programming languages out there, with Python making amazing progress in the last few years and Java holding onto its position.

It often seems that these languages are perfect, and in fact, they are capable of doing most of the tasks out there, however, there are key differences that could help you formulate your decision. We’ll start by explaining each language and key characteristics, then compare them in different fields in computer science to provide more clarity on your choices.

Java 

Java is a statically typed general-purpose programming language, it is an object-oriented and concurrent language. Java was meant to be WORA (write once run anywhere) language, it was designed to run on any platform and with as few dependencies as possible, with the help of the Java Virtual Machine (JVM).

Python

Python is a dynamically-typed general-purpose programming language. Python’s early development began at a research institute in the Netherlands. The original motivation behind it was to create a higher-level language to bridge the gap between C and the shell, as the author states, creating system administration utilities using C back at that time was pretty complicated. The syntax was also motivated by a few languages like Algol68, Pascal, and ABC and was meant to be readable and clean. You can read more about the history of python on the Python Author’s blog.

Now let’s have a look at key difference between Python and Java.

Python vs Java: Key Differences

Performance

Languages don’t have speed, they have only semantics. If you want to compare speed you must choose specific implementations to compare with each other. You can find a detailed Python vs Java performance comparison on this project called the benchmarks-game, where different languages are benchmarked in different programs.

Keep in mind that performance is not only a function of the language’s execution speed, the program’s implementation, and the third party libraries’ performance is usually the number one factor in the equation.

Popularity

Popularity has always been a game between these two languages, as they’ve been a close competitor in the top 3 positions of popularity, along with javascript. Before the Javascript revolution, Java was the number one most popular language. When Javascript first came out, the founders chose a name close to Java to make it gain traction.

As per Github’s Octoverse, Java was the second most used language on Github followed by Python. 

In Stackoverflow’s 2018 developer survey, Python has crowned the fastest growing programming language after taking over C# spot this year and surpassing PHP last year. Java is still ranked above Python being popular with 45% of developers while Python is at 39%, however that gap is closing.

It is safe to say that both languages reside around the same area in popularity.

Syntax

Python is a dynamically typed language, when you write Python, you don’t need to determine variable types, as the interpreter will infer these types and the checks will be made at runtime. Which results in an easier syntax that is quite similar to the English Language. Moreover, Python doesn’t use enclosing braces and follows indentation rules ( like how most people right pseudocode) which makes the code quite easy to read and friendly for beginners.

In this simple class definition, I’ve created a simple class called fruit, with a constructor, which is the code that will be executed when I create an instance of the object, and defined two simple functions as well, each printing one of the object’s attributes.

class Fruit:
 def_init_(mysillyobject, name, color);
 mysillyobject.name=name
 mysillyobject.color=color
 def myfunction(abc) :
 print("hello I'm a "+ abc.name)
 def mycolor(abc) :
 print("hello my Color is " + abc.color)
p1 = Fruit ("Apple", "red")
p1.myfunction()

Java, on the other hand, follows strict syntax rules, it’s a statically typed language where you need to explicitly declare your variable types and shouldn’t an anomaly be spotted, the code will not compile, to begin with. While it’s not the easiest thing for beginners, some developers find comfort with the clarity of statically typed languages, many developers don’t feel comfortable following indentation rules, especially with large code bases.

public class Fruit {
 String name;
 String color;
 public Fruit(String name, String color){
 this.color=color;
 this.name=name;
 }
 public void myfunction()
 {
 System.out.println("Hello I'm a :" +name);
 }
 public void mycolor()
 {
 System.out.println("Hello my color is:" + color);
 }

This is the equivalent to the Fruit class we have defined in Python with the exact same functionalities.

Jobs and Salary

There seems to be no objective difference or comparison between Python vs Java jobs or salary. Both are very popular so if you gain a decent expertise in either, you can start working as a software developer or intern to start your career. Availability of Jobs or Salary should not be be your criterion for choosing either of the programming language, choose the one that you could relate to better.

Python vs Java: Uses/Applications in various fields

Game Development

We’re not going to talk about general PC game development since neither Python nor Java can really compete with C++/C# in that area with their huge ecosystem. Moreover, game development is a field that requires the highest possible performance to provide seamless experiences to the users, and while Java and Python are not slow, they don’t provide the best performance for game development.

JMonkeyEngine is a popular open source game development engine with Java, while it’s not on par with Unreal and Unity it is certainly a powerful engine that will help you create some amazing games.

If you wish to experiment with computer graphics from scratch or build your own engine, OpenGL also provides bindings for the Java language.

While Python is not a powerful option on its own for game creation, there is Cocos, Panda3d, Pygame and a few other engines/frameworks for building games with Python.

However, Python isn’t completely ruled out for professional game development, it’s an important tool for a game developer, as Python is a popular scripting-language option for many developers including game developers. Editing Packages like Maya also use Python as a scripting language.

Web Development

Both languages are used in backend web development. Backend web development is the branch of web development concerned with creating the software that will run on the server. It’s the most popular development field according to StackOverflow’s developer survey.

Writing your own backend technology from scratch is not only hard, but it’s extremely hard to cover all design requirements from security to reliability and effectiveness. This is why developers have created frameworks which is an abstraction in software that allows you to build your backend technology without reinventing the wheel.

The most two popular frameworks for Python are Django and Flask. Flask is a micro web framework, it gives you the basic functionalities you’d need like routing requests without much overhead. Django is a more featured option and can help you build a powerful backend while capitalizing on efficiency and security, Django is equipped with a powerful ORM layer which facilitates dealing databases and performing different operations on the data.

As for Java, Spring is perhaps the most well-known Java backend framework with a massive ecosystem and a huge community around it. Spring is used by Orange, Dell, GE, and many other enterprises, and while it’s not as trending as Django nowadays, it is a powerful option for building enterprise-level applications.

Machine Learning

Since Python is syntactically very easy yet a fully-fledged general-purpose programming language, it became a popular option for people from different disciplines who wanted to experiment with machine learning and bring the power of AI into their respective fields. That’s why a lot of the development in AI and machine learning is done with Python with a huge ecosystem and libraries.

There is TensorFlow, Keras, Sickit-Learn, and Facebook’s PyTorch and it’s by far the most popular language in the field.

Java is also considered a good option when it comes to machine learning, it’s easy to debug and use and it’s already being used for large-scale and enterprise-level applications. Among the libraries, you could use in that area are Weka, Mallet, DeepLearning4, and MOA.  

Python vs Java Comparison Summary

To recap, here’s a quick comparison between the two languages covering the main points we discussed.

TechnologyPythonJava
PopularityVery popularVery popular
SyntaxEasy to learn and useComplex includes a learning curve
PerformanceSlower than Java in various implementationsRelatively very fast
Cross-PlatformYesYes, thanks to the JVM
Backend FrameworksDjango, FlaskSpring, Blade
Machine Learning LibrariesTensorflow, Pytorch,Weka, Mallet, Deeplearning4j, MOA
Game Development EnginesCocos, Panda3dJMonkeyEngine

Java and Python are both capable and popular languages, so there won’t be a lack of resources once you choose one and embark on your journey. If you’re new to programming, it’d be better to stick with Python just because it’s really easy and uses English-like syntax, it’s used in many Computer Science introductory courses around the world. However, if your goal is to build enterprise-level applications coming from a C/ C++ world, then Java would probably feel pretty familiar to you. It all goes down on what you plan to build and where you feel like journeying with your new skill.