Resolved Client doesn't start

Hi,
I just downloaded RuneMate and when I attempted to launch it, it wouldn't do open.

I'm running Linux Ubuntu 64 bit.
I tried launching it by making it into an executable(chmod +x RuneMate.jar) but it still wouldn't open.
I opened my terminal and ran it from there(using java -jar RuneMate.jar) and got this error:

Code (Text):

1. Exception in thread "main" java.lang.UnsupportedClassVersionError: com/runemate/Boot : Unsupported major.minor version 52.0
2.     at java.lang.ClassLoader.defineClass1(Native Method)
3.     at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
4.     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
5.     at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
6.     at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
7.     at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
8.     at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
9.     at java.security.AccessController.doPrivileged(Native Method)
10.     at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
11.     at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
12.     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
13.     at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
14.     at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

Any idea what's causing this or how to fix it?

Edit: Sorry, didn't notice

Thanks.

 

Updated to Java 8 and it works. Thanks