why does my computer keep saying I need to install Java?

You have installed a program that either requires a specific version of Java or requires a Java Virtual Machine (JVM), or requires a 32-bit version of Java.

When you go to Java.com, the only thing you are installing is a Java Runtime Environment (JRE) which supports plug-ins in the web browser. If the program needs to run java code that is on your computer, the plug-in is insufficient.

The legacy Java 6 released by Apple years ago will often solve all of the above issues as it would be the version the software was hard-coded to use, has a 32-bit version, and includes both the JVM and JRE.

https://support.apple.com/kb/DL1572?locale=en_US

If you want to use a more recent version of Java, then you can try downloading the Java Development Kit from the Oracle website (search for Java SE JDK).

However, if the program was coded poorly, it will only work with Apple's Java 6.

There are two javas...

The current one from Oracle, and the legacy one from Apple. They locate their files in different places.

To stop the messages, install the legacy one from Apple:

Java for OS X 2015-001

What happens if I have installed both? When I try to run Java Applets in Firefox a message appear saying that I don't have Java installed or something is blocking Java.

penavasal wrote:

What happens if I have installed both? When I try to run Java Applets in Firefox a message appear saying that I don't have Java installed or something is blocking Java.

You can have multiple versions of Java installed. A well-written program will determine which versions you have loaded and choose the most appropriate version or your preferred version. The ones that keep asking for the Legacy Java 6 weren't well-written.

So, this is not a problem of the Java version, because the applet would recognize which one to work with. But, why this applet is not working and telling me that I don't have Java installed?

penavasal wrote:

So, this is not a problem of the Java version, because the applet would recognize which one to work with. But, why this applet is not working and telling me that I don't have Java installed?

I don't use Firefox, so I don't know how it looks for the Applet or if it uses the standard plug-ins folder.

Do you have this file,

/Library/Internet Plug-Ins/JavaAppletPlugin.plugin

I use firefox because I find this problem when I use Safari:

Error: Error calling method on NPObject.

penavasal wrote:

I use firefox because I find this problem when I use Safari:

Error: Error calling method on NPObject.

I have no idea what that means, but I've never seen it. Perhaps you have more problems with interfering software than just Java.

penavasal wrote:

What happens if I have installed both? When I try to run Java Applets in Firefox a message appear saying that I don't have Java installed or something is blocking Java.

Are you sure it is complaining about java and not javascript? Typically web pages include javascript code and if javascript is not enabled in your browser you may get an error when displaying the page.

When I try to use the website on Firefox it says that I don't have Java installed, but I recognize that I don't know if this is a Javascript or Java problem. If it was Javascript, what do you propose to do? Thanks

From: http://activatejavascript.org/en/instructions/firefox

Firefox

Follow these instructions to activate and enable JavaScript in Firefox.

PC & MAC

1. Open a new Firefox browser window or tab.
2. Copy the following then paste it into the Firefox address bar: about:config
3. Hit the Enter key.
4. On the following page, click the button: "I'll be careful, I promise!"
5. Find the javascript.enabled row under the Preference Name heading.
6. Double-click anywhere within the javascript.enabled row to toggle the value from "False" to "True".
7. Finally, refresh your browser.

This may be an old thread but I seemed to develop the problem recently on my MacBook Pro running El Capitan 10.11.5. I usually use Safari (9.1.1) and the issue was driving me nuts.

Installing the "old" Apple Java did not work. Installing the Java SDK from Oracle eliminated the annoying message.

I'm not expert enough to know why this fixed things - but it seems to have done so. Let's hope it sticks.....

DB