Virtual machines have long ceased to be some kind of abstract concept and today they are accessible and understandable for any user. One of the most necessary of its kind is the Java Virtual Machine (JVM), which is installed on Windows systems from the very first installation of the OS itself. However, quite often it may be necessary to install it yourself, supplement or update the components of an existing platform. Further it is proposed to figure out what it is all about, why you need to, how to install the necessary components yourself and solve some problems associated with starting VMs in Windows systems.
What is a Java virtual machine?
Let's start by determining what this platform actually is, so that ignorant users immediately realize why it is required to install it on their own computers. In a general sense, this platform and its components are usually used to execute all kinds of scripts and applets written in the Java programming language when you visit websites containing relevant content. And these can be multimedia elements in all manifestations, some simple games, add-ons for using banking services, interactive cards, etc.
In addition, support for this platform is actively used in almost all mobile phones, despite the fact that they have their own operating systems. Have you ever noticed that on old phones that did not have modern OSs like Android or iOS, you could easily install applications (most often games) from JAR and JAD files? It was Java support that allowed this to be done. And today, such support is available in all mobile systems.
Finally, it is worth noting separately that the Java Virtual Machine is extremely necessary for many programmers and web designers to develop their own applets and applications. Thus, it becomes quite obvious that you need to have it on your computer in any case.
However, users who are not versed in the intricacies of using the Java virtual machine will be surprised that it will be impossible to run it just like that. Yes, indeed, this is true, since the main executable environment does not have a graphical interface, and you can use it only by integrating it into web browsers installed on your computer or laptop, or bundled with an IDE.
Preliminary check of the installed version
First, let's check if Java VM is installed on your system. To check, call the command console (cmd) by any method convenient for you (not necessarily as administrator), and then issue the java –version command to execute.
If the environment is installed, the information shown in the image above will be displayed, where priority should be paid to the platform version. Since it is not always updated automatically when installing updates for Windows systems themselves, it is strongly recommended that you perform such an update manually by downloading the necessary content from official resources and then installing it yourself.
What do you need for work?
In general, it is worth mentioning separately that the Java Virtual Machine is only one of the many components of the entire platform. So, those involved in creating applications need to install a specialized JDK (Java Development Kit), and an ordinary user will only need the JRE executable environment, where it will be impossible to create their own applets, but it will be possible to run and use ready-made programs written in Java. But if you want to become a qualified developer, you may need to choose an IDE kit for yourself (at the moment, the most common and recommended for installation and use are Eclipse and NetBeans).
Where and what to download for installation on Windows?
As for downloading the components necessary for installing or updating the Java virtual machine, you can visit java.com, where in the download section you will immediately be prompted to download the installer that matches your operating system.
If you need additional components, you can turn to oracle.com, where the full Java SE (JDK) version 12, some earlier platform modifications, and the NetBeans suite are currently available.
Here it is worth giving a little explanation, since many users may have doubts about which kit to download, because the site has as many as three modifications! Apparently, you will only need the SE version, since EE is an enterprise-oriented development environment, and ME is a similar platform for working with mobile systems.
Install Java Virtual Machine
So, we assume that the installer is downloaded from one of the official sources to the user computer.
Now the installer of the Java virtual machine for Windows 10 (as in the example below) needs to be run as administrator (if your built-in superuser account is not deactivated).
You can not change anything in the initial installation window, just click on the installation confirmation button, after which the process of copying files starts to integrate all the necessary components into the system.
When the main components are copied, you must agree to uninstall the obsolete components (if any are found) and click the corresponding button (Uninstall). At the end, you will need to click the continue button again, after which a message appears indicating a successful installation.
Note: keep in mind that the applet responsible for tracking updates will be immediately added to the startup section of the system. If you do not need it, you can disable it by using the appropriate section either in the configuration (msconfig) for Windows 7, or in the "Task Manager" (taskmgr) for Windows 8 and 10.
Error creating platform
Finally, the platform is installed. Now let's pay attention to some failures and errors that may appear after the integration of components into the system is completed. The very first and most common problem is the inability to start the Java virtual machine (for Windows of the latest generations, this problem is usually not observed, but in unsupported versions of systems like XP they can manifest themselves).
To fix the problem, use the properties of the computer, go to additional parameters, go to the section of environment variables, create a new parameter with the name and value shown in the image below.
In the example, the indicated value corresponds to 512 MB of allocated RAM that the machine is allowed to use. If necessary, you can increase it.
Error opening registry keys
Sometimes a Java virtual machine for Windows 7 and above may throw out a registry access error, especially when it works through the command line. In this situation, you need to go to the System32 directory and delete three executable EXE files with the following names: java, javaw and javaws. After that, you just need to reinstall the environment using the previously downloaded installer file.
Error finding the main class
Another failure, in which the virtual machine spontaneously and in emergency mode shuts down, can be fixed in the following way.
First, run the malware seeker and removal tool by typing the mrt command in the Run console, click the continue button, and then select the full scan. At the end of the process, completely reboot the system, then enter the configuration (msconfig) or the “Task Manager”, and then deactivate the startup component called WJView.exe in the list. After this, the system restart must be performed without fail.
Error opening jar files
Finally, the error related to the impossibility of opening objects of the JAR format corresponding to the platform and the virtual machine is corrected in the following way.
In the “Control Panel”, enter the default program section, click on the link for mapping file types or protocols to individual programs, select the .jar extension from the list, click the program change button and select the Java virtual machine. If the problem persists, try reinstalling the entire platform completely.