This minHour teaches you how to open and run executable JAR files on a Windows or Mac computer. JAR (Java Archive) files contain data to be used with the Java program. Most JAR files are simply containers for data that another program needs to run with Java; therefore you cannot run these files and nothing will happen when you double-click them. Similarly, most executable JAR files are downloaded as installation files to install applications or programs. Therefore, you should double check that you have the right JAR file designed for your operating system if you are having problems opening the file.
On Windows
Install Java
You can’t run JAR files without Java installed on your computer. If you don’t already have Java installed, go to Java’s website at https://www.java.com/en/download/ and click the button below the latest version of Java, then install Java once it downloads.
- You may have to restart your computer for Java to be fully implemented.
Double-click the JAR file.
If it’s executable and you have Java installed, it should open. If it doesn’t open, proceed to the next step.
- You may see a pop-up window asking which program you want to use to open the file. If so, click Java(TM) and then click OK.
Make sure your JAR file is an executable file.
JAR files that you download in order to set up programs are different from “library” JAR files, which store data that a program running Java can use. Since they don’t have interfaces like executable JAR files, you cannot run non-executable JAR files.
- For example, many of the JAR files in a program’s data folders are not executable files.
- If you downloaded your JAR file from online, make sure you clicked the Windows version of the file rather than the Mac version.
Update Java.
If your JAR file produces an error when you double-click it, you may need to update Java. To do so:
- Open Start.
- Scroll down and click the Java folder.
- Click Check For Updates.
- Click Update Now on the Update tab.
Double-click your JAR file again.
If it doesn’t open this time, the file you’re trying to open isn’t executable and thus cannot be “run” in the traditional sense.
On Mac
Install Java
You can’t run JAR files without Java installed on your computer. If you don’t already have Java installed, go to Java’s website at https://www.java.com/en/download/ and click the button below the latest version of Java, then install Java once it downloads.
- When installing a non-Apple file on Mac, you may have to first click OK on the warning, click the Apple menu, click System Preferences, click Security & Privacy, unlock the menu, click Open Anyway next to the file’s name, and then click Open when prompted before you can install the file.
Try double-clicking your JAR file.
If it’s executable and you have Java installed, it should open. If double-clicking the file doesn’t open it, proceed to the next step.
Make sure your JAR file is an executable file.
JAR files that you download in order to set up programs are different from “library” JAR files, which store data that a program running Java can use. Since they don’t have interfaces like executable JAR files, you cannot run non-executable JAR files.
- For example, many of the JAR files in a program’s data folders are not executable files.
- If you downloaded your JAR file from online, make sure you downloaded the Mac version and not another operating system’s version.
Update Java.
If your JAR file produces an error when you double-click it, you may need to update Java. To do so:
- Open the Apple menu.
- Click System Preferences.
- Click Java.
- Click the Update tab.
- Click Update Now.
Double-click your JAR file again.
If it doesn’t open this time, the file you’re trying to open isn’t executable and thus cannot be “run” in the traditional sense.
Tips
- Java programs should work on all platforms. If one does not, either it was not coded properly, or it is a very specialized program that calls on system resources or other programs.
- A .jar file may be a program or a library. If it’s a library, it has no executable class inside and thus there is no use in running it.
Warnings
- Java is safer than most programming languages, but malware written in Java still exists. Be cautious of running JAR files downloaded from online.