Solution of "Can you Acess?" in Java 15

import java.io.; import java.lang.reflect.; import java.util.; import java.util.regex.; import java.security.*;

public class Solution {

public static void main(String[] args) throws Exception {
    DoNotTerminate.forbidExit();    

    try{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = Integer.parseInt(br.readLine().trim());
        Object o;// Must be used to hold the reference of the instance of the class Solution.Inner.Private

    Inner inner = new Inner();
    o = inner.new Private();
    Inner.Private innerPrivate = (Inner.Private) o;
    String response = innerPrivate.powerof2(num);
    System.out.println(num + " is " + response);

    System.out.println("An instance of class: " + o.getClass().getCanonicalName() + " has been created");

    }//end of try

    catch (DoNotTerminate.ExitTrappedException e) {
        System.out.println("Unsuccessful Termination!!");
    }
}//end of main
static class Inner{
    private class Private{
        private String powerof2(int num){
            return ((num&num-1)==0)?"power of 2":"not a power of 2";
        }
    }
}//end of Inner

}//end of Solution

class DoNotTerminate { //This class prevents exit(0)

public static class ExitTrappedException extends SecurityException {

    private static final long serialVersionUID = 1L;
}

public static void forbidExit() {
    final SecurityManager securityManager = new SecurityManager() {
        @Override
        public void checkPermission(Permission permission) {
            if (permission.getName().contains("exitVM")) {
                throw new ExitTrappedException();
            }
        }
    };
    System.setSecurityManager(securityManager);
}

}