Linux Jetty after installation start error-unsupportedclassversionerror---unsupported major.minor version 52.0__linux

On Linux for the first time after loading jetty. Run the error below

Exception in thread "main" java.lang.unsupportedclassversionerror:org/eclipse/jetty/start/main:unsupported Major.minor version 52.0 at Java.lang.ClassLoader.defineClass1 (Native method) at Java.lang.ClassLoader.def
        Ineclass (classloader.java:800) at Java.security.SecureClassLoader.defineClass (secureclassloader.java:142) At Java.net.URLClassLoader.defineClass (urlclassloader.java:449) at java.net.urlclassloader.access$100 (Urlclassloa der.java:71) at Java.net.urlclassloader$1.run (urlclassloader.java:361) at Java.net.urlclassloader$1.run (UR lclassloader.java:355 in Java.security.AccessController.doPrivileged (Native method) at Java.net.URLClassL Oader.findclass (urlclassloader.java:354) at Java.lang.ClassLoader.loadClass (classloader.java:425) at SUN.M Isc.
        Launcher$appclassloader.loadclass (launcher.java:308) at Java.lang.ClassLoader.loadClass (classloader.java:358) At Sun.launcher.LauncherHelpeR.checkandloadmain (launcherhelper.java:482) 

Major.minor version52 requirements are at least JDK8.0 above.

There are two reasons:

1. The JDK version of Linux is below 1.8. Reloading a jdk1.8+ can solve

2. The installed JDK version reached 1.8, but the machine did not restart, reboot can be resolved.