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What's the Difference Between Java and JavaScript?

For those who are just getting started with programming, be it server-side or client-side, it’s inevitable that you’re going to come across the programming languages Java and JavaScript.

If you’ve any experience programming in one or the other, then you know they aren’t the same, and you probably know the difference between the two. But if you’re just getting started, this can be confusing for some reasons, the first being how the languages are named.

Though they share the name "Java" in their name, they share very few attributes and characteristics. In this article, we’re going to take a look at some of the key differences in the languages by examining some of the high-level attributes each language offers.

Ultimately, we’re seeking to help those of you who are brand new to programming and aren’t sure which language you’d like to learn (or learn first!). In this article, we’re going to take a look at some of the key differences that exist in the languages and where each is applicable an attempt to arm you with the information necessary to help you take the next step in your career.

Java and JavaScript

Perhaps the best point to make when starting off in distinguishing these two languages is to draw the comparison like this:

Java is to JavaScript as ham is to hamster.

Unfortunately, I can’t claim this analogy as my own. Instead, it’s coined by Jeremy Keith , but it makes an excellent point: About the only thing the languages have in common is that they share the name "Java" in their name. 

One similarity is that the languages are what we call "C-style" languages in that their syntaxes are like those of C. That is, they both have functions, parentheses, brackets, and semicolons.

Other than that, though, there’s very little similarity. Throughout the rest of this article, we’re going to look at each language at a very high level to give you an idea as to what each language offers and the features of each.

Once done, you should be able to see a difference in the two languages and, although they are named similarly and have some similar syntax, that’s about the only thing they have in common.

So let’s get started.

What Is Java?

We’ve covered Java in other tutorials on this site and will continue to do so as the language continues to grow over time.

Java was conceived under the idea of "write once, run anywhere", meaning that you could write a program on a computer and then deploy it to any device that had the Java runtime.

But wait: What’s the Java runtime?

First, it’s important to understand that Java is a compiled language, though it’s not compiled to binary, executable code. Instead, it’s compiled to bytecode .

Java bytecode is the instruction set of the Java virtual machine. Each bytecode is composed by one, or in some cases two bytes that represent the instruction (opcode), along with zero or more bytes for passing parameters.

Sounds less than exciting, doesn’t it? That’s okay! As developers, we aren’t responsible for writing the bytecode. Instead, the Java compiler compiles our code to bytecode.

This bytecode is executed on top of the runtime, which runs in the context of another operating system. This operating system may run on a cell phone, it may run on another computer, it may run on Windows, OS X, Linux, or any other system on which it’s compatible. You can read all about it on this page .

It sounds neat, right? The thing is, it’s not without its challenges. It seems far easier than it is, and this is something that more advanced Java developers tackle. It’s outside the scope of this article. Instead, we’re going to focus on attributes of the language so that we can compare and contrast it with JavaScript.

But first, let’s look at some of the faculties we have to work in Java. It’s important to note that we work at a much higher level. For example, we get to work with the following constructors:

  • Classes are the foundation of any object-oriented based language. They allow us to define what characteristics and behaviors an object will exhibit once it has been instantiated.
  • Functions are the parts of classes that allow objects to  do something . A class that represents a  File  may allow us to read the contents of what it contains.
  • Properties, or attributes, are what describe a class. A  File , for example, may have permissions such as the ability to read or write to a file system. It may also have a path representing where it resides on the file system.
  • Inheritance is when one class can inherit certain properties from another class. This means that it receives all of the functions and properties from a parent class, and it can add its unique functionality.

If you’ve never written code before, some of this may sound like jargon. Understandably so! We have some resources that are available to help teach you what you need to know:

But before jumping too far into making a decision about what you want to learn, let’s take a look at JavaScript, as well.

What Is JavaScript?

I’ve covered JavaScript in much more detail in a previous article that you canread here, but I’ll be covering the high points, as previously mentioned, in this article. For a much deeper dive, take a look at what’s provided above.

JavaScript, at its core, is a dynamic language that’s untyped, and it’s interpreted. This means:

  • We, as developers, can easily extend certain aspects of the language by adding our code to pre-existing objects such as the object  String .
  • The untyped nature of the language means that we can declare strings, booleans, and numbers (versus integers, floats, and decimals) without having to state explicitly their type as we do in Java (and other languages).
  • The language is interpreted, meaning that it’s not compiled into an executable. Instead, it’s interpreted by a web browser or another piece of software on your computer that translates your instructions into machine code.

If you’re confused by any of this, don’t worry! We’ve all been there:

  • Defining variables?
  • Implementing functions?
  • Creating objects?
  • Setting up conditional statements?
  • And much more.

It’s a lot. I know. But the nice thing is that we have plenty of resources to get you up to speed with JavaScript. And once you learn the nuances of the language, it becomes easier and easier to work within its confines.

Remember, all of the "I’m not sure what I’m doing" is natural, and it’s part of the learning curve. If you’ve never seen any programming related to JavaScript, then I highly recommend checking out a couple of the following courses:

Once you get more familiar with the language, it’s also important to use proper tools for developing your applications. This includes using tools such as a debugger (which most modern browsers include). This is out of scope for this particular article, though.

A Note About Object-Orientation

Another important distinction to make is that JavaScript and Java are both considered object-oriented languages but for different reasons.

Java allows us to create instances of objects from classes that we create. Conversely, everything in JavaScript is an object. That means there are no classes. And because everything is an object, everything has methods and properties we can use.

In Java, when you create an instance of a class, you have access to the methods and properties that you expose through the class definition. If you have public properties, public functions, and so on, then the developer can use them.

In JavaScript, when you create a variable, an object, or even a function, you have the ability to call functions that exist not only on that object but on objects from which the given object derives its properties. This has to do with the prototypal inheritance nature of JavaScript, which you can read more aboutin this article.

Which One Should I Choose?

As you can see from the content above, the two languages—though both inspired by C regarding their syntax—are very different. Each also serves a different purpose.

Though you can write JavaScript on the server with technologies like Node.js, they aren’t the same type of applications that are built with Java. Additionally, though you can write server-side applications with Java, they aren’t the same type of applications that you typically write with JavaScript.

Instead, it’s often helpful to think about JavaScript being a language that’s best suited for client-side development, for applications that will run in a web browser, or for single-page applications. And it’s best to think of Java as a programming language that’s best used for writing server-side or desktop applications that can be run on a variety of different operating systems and devices.

Conclusion

Apparently, each of these languages offers their unique sets of advantages and disadvantages. Honestly, I think that much of what drives us to choose one language over the other has to do with what we want to do in terms of building solutions for ourselves and others.

If you wish to work on the web, then JavaScript is likely your best choice. If on the other hand, you want to write desktop applications, then Java isn’t a bad choice.

For those who are interested, it’s worth noting that JavaScript has become one of the de-facto languages of working on the web. It’s not without it’s learning curves, and there are plenty of frameworks and libraries to keep you busy, as well. If you’re looking for additional resources to study or to use in your work, check out what we have available in the Envato marketplace .

I spend the majority of my time working with WordPress and building solutions on top of it; however, I’m also a fan of JavaScript and blog about it from time to time . If you’re interested in other courses and tutorials I’ve written for Envato, please check out my profile page. Furthermore, you can read more articles about WordPress and JavaScript development  on my blog . Feel free to follow me on Twitter as well at  @tommcfarlin .

With that said, please leave any and all feedback in the comment feed below.

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