To solve this you need to uninstall Java 8 JDK which is recommends for you to download if you didn't have Java when you tried to open it for the first time (You can search on google how to uninstall it).
Then google JDK 7 and install that.
If this causes you technic launcher to crash then there is a fix which you can search up on google ("Technic Pack Java 7 fix)
I hope this helps you.