advanced java

// How to input arrays via scanner;
/* 
import java.util.Scanner;
public class PrimeNumbers{
public static void main (String[] args){
    int[] array = new int [5];
    Scanner in = new Scanner (System.in);

    System.out.println("Enter the elements of the array: ");
    for(int i=0; i<5; i++)
    {
        array[i] = in.nextInt();
    }
*/
//Executor- An object that executes submitted Runnable tasks.
/*The Java ExecutorService is the interface which allows us
to execute tasks on threads asynchronously */
/*Runnable is an interface that is to be implemented by a 
class whose instances are intended to be executed by a thread. */
/*Callable , represents an asynchronous task which can be
executed by a separate thread. For instance, it is possible 
to submit a Callable object to a Java ExecutorService which will 
then execute it asynchronously. */
 /*Synchronous (Sync) and asynchronous (Async) programming can
be done in one or multiple threads. The main difference
between the two is when using synchronous programming we can 
execute one task at a time, but when using asynchronous programming
 we can execute multiple tasks at the same time.*/
 /* The Callable object returns a Future object which
 provides methods to monitor the progress of a task being
executed by a thread. ... The future object can be used
 to check the status of a Callable and then retrieve 
the result from the Callable once the thread is done. */
/*A Java Future, java. ... Future , represents the result of an 
asynchronous computation.
 When the asynchronous task is created, a Java Future object 
 is returned. This Future object functions as a handle to the 
 result of the asynchronous task. */  
 /*taking input by buffered reader;
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in))
 char ch = char.parseint(br.readline()); */