Reading char from keyboard to stop threads?

Question

I want to kill all the threads an terminate my program execution when I enter some char, for example 'S'.
BUT, I dont want the execution flow to wait in the sentence 'prompt.read()' until I enter some character.
does somebody knows the solution?
this is my program:
import java.io.*;
public class Finalizadora extends Thread {
     public static boolean ejecucion = true;
     public void run() {
          while (ejecucion) {
               try {
                    sleep(1000);
               } catch (Exception e) {
                    // Si falla el sleep lo simulamos
                    for (int i = 0; i < 1000 * 10; i++) {
                    } // fin del for
               } // fin del try
               try {
                    BufferedReader prompt = new BufferedReader(new InputStreamReader (System.in));
                    if (prompt.read() == 'S') {
                        ejecucion = false;
                    } // fin del if
               } catch (Exception e) {
                    System.out.println("SOME FAILS!!");
               //System.out.println("--------------------");
          } // fin del while
          System.out.println("ENDING...");          
     } // fin de parsear
} // fin de Finalizadorathanks!

Answer 1

Hello.I cant read chars from a file.I am trying to fing to character with Max Occurrence in a file but when I run it it stops abruptly.This is my code.Can you help me please.Thank you
* To change this template, choose Tools | Templates
* and open the template in the editor.
* @author Dimitrios
/*Assuming that the char with the max frequency in an standard English test is 'E' we can guess
* that the char with the max frequency in the cipher text is E.This will
* lead us to an approximation of the Key by shifting */
import java.io.*;
public class Frequency_Decprypt {
public static int Occurrence(String str, char ch) {
int occur=0;//the occurrence of char ch in the string
for(int i=0;i<str.length();i++){
if(str.charAt(i)==ch){
occur++;
return occur;
public static char Frequency() throws IOException{
BufferedReader in;
FileReader fr;
int key=0;
char Max_FreqChar=' ';//the char with the max frequency
int Max_Freq=0;// the max frequency of a char
try{
fr=new FileReader("Encrypted.txt");//the input file to read
in=new BufferedReader(fr);
//read a line from file
String s=in.readLine();
while(s!=null){
for(int i=0;i<s.length();i++){
if(Occurrence(s,s.charAt(i))>=Max_Freq){
Max_Freq=Occurrence(s,s.charAt(i));
Max_FreqChar=s.charAt(i);
s=in.readLine();
fr.close();
//key=(int)('e'-Max_FreqChar);
//key=Math.abs(key);
} catch (FileNotFoundException e)
{ System.out.println("File not found");}
return Max_FreqChar;
}