Java is both a programming language and a platform used by a large number of websites and applications. When Java is not enabled, you may have difficulty visiting certain websites or using certain applications. To use Java, you need to enable add-ons on the Java Control Panel and on your Internet browser.
Steps
Method 1 of 6: Enable Java on Microsoft Windows

Step 1. Click the Start button and select Control Panel

Step 2. Type "Java" into the search bar of your Windows Control Panel

Step 3. Click on the Java icon to access the Java Control Panel

Step 4. Click on the Security tab

Step 5. Check the box next to Enable Java content in browser

Step 6. Click Apply, then select OK to save your new Java configuration settings

Step 7. Close all open Internet browsers, and then relaunch them to allow the new Java settings to take effect
Method 2 of 6: Enable Java on Mac

Step 1. Click on the Apple icon at the top left of your Mac desktop

Step 2. Click System Preferences

Step 3. Click Java to access the Java Control Panel

Step 4. Click on the Control Panel tab called Security

Step 5. Check the box next to Enable Java content in browser

Step 6. Click Apply and then select OK
Your new Java settings will now be saved.

Step 7. Close all Internet browsers and then reopen your browser
Your new Java settings will now be activated.
Method 3 of 6: Enable Java on Microsoft Internet Explorer

Step 1. Hover over Tools and select Internet Options

Step 2. Click the Security tab and select Custom Level

Step 3. Select Enable next to the option called Java applet script

Step 4. Click the OK button to save your changes
Method 4 of 6: Enable Java on Google Chrome

Step 1. Type about: plug-ins in the address bar of Google Chrome

Step 2. Click the Activate link under the Java section
No action is required if the link is disabled.
Method 5 of 6: Enable Java on Mozilla Firefox

Step 1. Click on the Firefox button in the top left corner of your browser

Step 2. Select Add-ons
The Add-ons Manager will open in a new tab.

Step 3. Click Plugins

Step 4. Click Activate next to “Java (TM) Platform”
No further action is required if the button indicates disabled.
Method 6 of 6: Enable Java on Apple Safari

Step 1. Click Safari in your Safari browser then select Preferences

Step 2. Click on the Security tab

Step 3. Check the box next to Enable Java

Step 4. Close the Safari preferences window to save your changes
Advice
- If you are using a device other than a computer, such as a tablet, smartphone, or game console, it may not support the Java extension. Check with the manufacturer to see if Java is supported.
- If you are still having difficulty getting Java to work after following the above steps, you should install a new version of Java. To download the brand new version, click on one of the Java links displayed in the Sources and citations section at the bottom of this article, then select To download from the home page. Java will walk you through the installation process.