Hey try this solution - https://confluence.atlassian.com/doc/setting-the-java_home-variable-in-windows-8895.html

Do the following steps:-

1. Right-click the My Computer icon on your desktop and select Properties
2. Click the Advanced tab
3. Click the Environment Variables button
4. Under System Variables, click New
5. Enter the variable name as path
6. Enter the variable value as the path for the Java Development Kit. For this go to bin directory of your java folder. In my case path is like this: "C:\Program Files\Java\jdk1.7.0_79\bin"
7. Click OK
8. Click Apply Changes
9. Now open command prompt and type javac and then press enter. If you found java details that means you have successfully installed java in your window system.

After this you can able to install Android SDK in your system.