What is Java? Definition, Meaning & Features of Java Platforms

In this Java tutorial, you will learn-

• What is Java?
• What is Java Platform?
• Java Definition and Meaning
• What is Java used for?
• History of Java Programming Language
• Java Versions
• Java Features
• Components Of Java Programming Language
• Different Types of Java Platforms
• What is a PC?
• What is Assembly Language?
• What are Assembler and Compiler?
• How Java Virtual Machine works?
• How is Java Platform Independent?

This video introduces the Java platform, and explains why Java is a platform as well as a programming language.

To understand Java programming language, we need to understand some basic concept of how a computer program can run a command and execute the action.

What is a PC?

A computer is an electronic device capable of performing computations. We all know that it is composed of a monitor, keyboard, mouse, and memory to store information. But the most important component of the computer is a PROCESSOR. This does all thinking of computer, but the question is how the computer does this thinking? How does it understand the text, images, videos, etc.?

What is Assembly Language?

The computer is an electronic device, and it can only understand electronic signals or binary signals. For example, the 5-volt electronic signal may represent binary number 1, while 0 volts may represent binary number 0. So your PC is continuously bombarded with these signals.

Eight bits of such signals are grouped together to interpret Text, numerical, and symbols.

For example, the # symbol is identified by the computer as 10101010. Similarly, the pattern for adding a function is represented by 10000011.

This is known as 8-bit computing. Current day processor is capable of decoding 64-bit time. But what is the relation of this concept with the programming language JAVA? Let understand these as an example.

Suppose if you want to tell the computer to add two numbers (1+2) represented by some binary numbers (10000011), how are you going to tell this to your computer? Yes, we are going to use assembly language to get our code executed.

"Assembly Language is the most elementary form of software development languages."

We are going to give the command to a computer in this format, as shown below. Your code to add two numbers in this language would be in this order.

• Store number 1 at memory location say A
• Store number 2 at memory location say B
• Add contents of Location A & B
• Store results

But how are we going to do this? Back in the 1950s, when computers were huge and consumed a great deal of power, you would convert your assembly code into corresponding machine code to 1 and 0's using mapping sheets. Later, this code will be punched into the machine cards and feed to the computer. The computer will read these codes and execute the program. This would be a long process then until ASSEMBLER came to help.

What are Assembler and Compiler?

With the advancement in technology, i/o devices were invented. You could directly type your program into the PC using ASSEMBLER. It converts it into the corresponding machine code (110001..) and feeds it to your processor. Coming back to our example addition of (1+2), the assembler will convert this code into machine code and output.

That apart, you will also have to make calls to create Operating System provided functions to display the code's output.

But alone the assembler is not involved in this process; it also requires the compiler to compile the long code into a small chunk of codes. With the advancement in software development languages, this entire assembly code could shrink into just one line print f 1+2 A with the software called COMPILER. It is used to convert your c language code into assembly code. The assembler converts it into corresponding machine code. This machine code will be transmitted to the processor. The most common processor used in PC or Computers are the Intel processor.

Though present-day compilers come bundled with assembler can directly convert your higher language code into machine code.

Now, suppose the Windows operating system runs on this Intel processor, a combination of Operating System plus the processor is called the PLATFORM. The most common platform in the world is Windows, and Intel is called the Wintel Platform. The other popular platforms are AMD and Linux, Power PC, and Mac OS X.

Now, with a change in processor, the assembly instructions will also change. For example:

• Add instruction in Intel may be called ADDITION for AMD
• OR Math ADD for Power PC

And, with a change in Operating System, OS-level calls' level and nature' will also change.

As a developer, I want my software program to work on all platforms to maximize my revenues. So I would have to buy separate compilers that convert my print f command into the native machine code.

But compilers come expensive, and there is a chance of compatibility issues. So buying and installing a separate compiler for different OS and processor is not feasible. So, what can be an alternative solution? Enter Java language.

How Java Virtual Machine works?

By using Java Virtual Machine, this problem can be solved. But how it works on different processors and O.S. Let's understand this process step by step.

Step 1) The code to display the addition of two numbers is System.out.println(1+2), and saved as a .java file.

Step 2) Using the java compiler the code is converted into an intermediate code called the bytecode. The output is a .class file.

Step 3) This code is not understood by any platform, but only a virtual platform called the Java Virtual Machine.

Step 4) This Virtual Machine resides in the RAM of your operating system. When the Virtual Machine is fed with this bytecode, it identifies the platform it is working on and converts the bytecode into the native machine code.

While working on your PC or browsing the web, whenever you see either of these icons, be assured the java virtual machine is loaded into your RAM. But what makes Java lucrative is that code, once compiled, can run not only on all PC platforms but also on mobiles or other electronic gadgets supporting Java.

Hence,

"Java is a programming language as well as a Platform"

How is Java Platform Independent?

Like the C compiler, the Java compiler does not produce native executable code for a particular machine. Instead, Java produces a unique format called bytecode. It executes according to the rules laid out in the virtual machine specification. Therefore, Java is a platform-independent language.

Bytecode is understandable to any JVM installed on any OS. In short, the java source code can run on all operating systems.

Summary:

• Java is a multi-platform, object-oriented, and network-centric programming language Java is a general-purpose, class-based, object-oriented programming language.
• Java Platform is a collection of programs that help programmers to develop and run Java applications efficiently.
• Meaning of Java: Java is a multi-platform and network-centric programming language.
• It is mainly used for developing Android Apps and Enterprise Software.
• 2009, Oracle Corporation acquired Sun Microsystems and took ownership of three key Sun software assets: Java, Solaris, and MySQL.
• The latest version of Java released on September 15th, 2020
• The best feature of the Java is that it is one of the easiest programming languages to learn.
• Four types of Java Programming language platforms are: 1) Java Platform, Standard Edition (Java SE) 2) Java Platform, Enterprise Edition (Java EE) 3) Java Platform, Micro Edition (Java ME) 4) JavaFX
• A computer is an electronic device capable of performing computations.
• The computer only understands electronic signals or binary signals.
• Assembler is an advanced technology that converts source core to corresponding machine code (110001..) and feeds to your processor.