Let's say that you want to know where a file went. You have a folder full of files, and one of them has gone missing. Fortunately, your computer keeps track of each file by "stamping" it with a number, so whenever you save a new file, the computer stamps it with a higher number than the previous one.
If you wanted to know which file was created most recently, all you would have to do is look at the folder and count it up by one. If there were 10 files in the folder and the last one that was saved or put into the folder had several 1536, then that would be the file that's missing. You could also go the other way, take a look at the first file, compare it to the last one and see how many files have come in between.
This sounds simple enough so far, but what if you wanted to perform this task on every single file on your computer? This is where Java comes into play. The Java programming language provides a way for your computer to understand instructions that are written in its language, even when you are running one of Microsoft Windows operating systems. This means that any program that performs these steps can be written once in Java and run anywhere there's a version of java installed without having to rewrite it for each system or platform you want it to work with.
What does java do for my computer?
In simple terms, it allows programs to run on your computer without the need for a compiler. A compiler is a program that takes code written in a programming language and turns it into something that the computer understands (binary code). Without a compiler, all you could ever have would be text files containing instructions. These text files would look like gibberish to humans but instruct computers in their language.
Nowadays there are many compilers, each one designed to turn its respective programming language's source code into an executable file or binary file. For us to use them properly, we need to know how they work and what they do when turning our source code into an executable file. First of all, when writing our source code in a programming language, we need to specify that the code is written for a compiler and not for a computer. Second of all, we need to tell the compiler where we got our source code from and what kind of text file it's supposed to be turning into an executable program.
What is Java Plug-in software?
Source code can be written in many different programming languages, but most compilers are only able to understand their language. Some compilers however can understand more than one programming language. These "multi-language" compilers are quite popular these days since they allow programmers to work together with other programmers using their own chosen languages or sets of tools.
Some compilers also need additional files that contain the extra code required for the compiler to work. This code is called a library and is placed alongside your source code file when you tell the compiler where it should look for its input. The library contains functions that the compiler will automatically search for as it tries to turn your source code into something executable by a computer.
What is the Java Runtime Environment?
Using a compiler to turn your source code into an executable program is not as simple as telling it where the file is and then letting it do its job. If you try that, you will end up with a very big executable file that's missing many of the libraries needed for the program to run properly. This process of removing unneeded code from executables to keep their size down is called "compiling" and is done by another tool known as a linker.
The linker takes all required files (libraries) and places them inside your final executable so that when you run it on your computer, everything needed for it to work properly will be there waiting for it.
Important of Java on my Computer?
For end-users, it is important to know that using java on your computer allows the installation of programs (or applets) that can be executed like any other program. These programs are sometimes referred to as applications (a collection of files containing instructions for a computer in one single package). Since they don't require compilers or linkers, all you need to do is download them and run them like any other executable file. The Java Runtime Environment contains an interpreter that reads the bytecode produced by the JIT compiler and then runs it inside your computer.
The output of this process is an application that you can copy onto any other compatible machine's hard drive, unpack and start using immediately. This kind of application portability would not be possible if it wasn't for the Java Runtime Environment.
The code that's inside these executable files is run by the JVM (Java Virtual Machine). The JVM is a piece of software running inside your computer, much like any other program, you have installed there. It makes sure that the bytecode you downloaded to run on your machine will be executed in the same way as intended by its author(s), so nobody can take advantage of security holes or bugs without people knowing about it. This ensures safe use of java applets and applications over the Internet, which would not be possible without this sandbox approach provided by all modern browsers that support java.
Java is a programming language originally developed by James Gosling at Sun Microsystems in the early 1990s. Designed to be simple, portable, and reliable, Java is now used on countless platforms worldwide. A compiler reads source code written in Java and converts it into bytecode which can then be executed by something called the Java Virtual Machine (JVM). This virtual machine runs inside every program that supports java - most browsers are capable of running Java applets or applications, as well as many desktop environments including macOS X and Microsoft Windows. Although apps running on the JVM cannot interact directly with your hardware they require surprisingly little memory compared to other languages due to their platform independence.