Question

I have problem with declaration of variable. iam trying to prepare code using Multi threading
but i have problem with declaration of variable. Now iam confused, whether is possible to put Scanner into second not main class- i suppose that yes, but i don´t know how declare variable. Exception is – Exception in thread “main” java.lang.RuntimeException: Uncompilable source code – non-static variable this cannot be referenced from a static context
at test1.PIN.main …

public class PIN{

    static int a;

class Runner extends Thread{

public void run(){

    Scanner sc = new Scanner(System.in);
    for(int i= 1; i<4; i++){
    System.out.println("PUT your PIN: ");
    int a = sc.nextInt();

                try {
                    Thread.sleep(100);
                } catch (InterruptedException ex) {
                    Logger.getLogger(PIN.class.getName()).log(Level.SEVERE, null, ex);
                }

 if(a ==1234){
     System.out.println("PIN  OK");
 } else {System.out.println("PIN NOK");}   

}
}
}

public static void main(String[] args){

    Runner r = new Runner();
    r.start();

Answer 1

Declare Runner static inner class. Non static inner classes are instance bound so you need outer class instance to create object of non-static inner class. And because your inner class is not static you can not access it inside main which is static-context

static class Runner extends Thread