Класът Random - Homework

import java.util.Random;
public class Digits {

	 private static final String CAPITAL_LETTERS =

		        "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

		    private static final String SMALL_LETTERS =

		        "abcdefghijklmnopqrstuvwxyz";

		    private static final String DIGITS = "0123456789";

		    private static final String SPECIAL_CHARS =

		        "~!@#$%^&*()_+=`{}[]\\|':;.,/?<>";

		    private static final String ALL_CHARS =

		        CAPITAL_LETTERS + SMALL_LETTERS + DIGITS + SPECIAL_CHARS;



		    private static Random rnd = new Random();



		    public static void main(String[] args) {

		        StringBuilder password = new StringBuilder();



		        // Генерира 2 произволни главни букви

		        for (int i=1; i<=2; i++) {

		            char capitalLetter = generateChar(CAPITAL_LETTERS);

		            insertAtRandomPosition(password, capitalLetter);

		        }



		        // Генерира 2 произволни малки букви

		        for (int i=1; i<=2; i++) {

		            char smallLetter = generateChar(SMALL_LETTERS);

		            insertAtRandomPosition(password, smallLetter);

		        }



		        //Генерира се 1 произвона цифра

		        char digit = generateChar(DIGITS);

		        insertAtRandomPosition(password, digit);



		        // Генерира 3 символа

		        for (int i=1; i<=3; i++) {

		            char specialChar = generateChar(SPECIAL_CHARS);

		            insertAtRandomPosition(password, specialChar);

		        }



		        // Генерира няколко произвилни символа (между 0 и 7)

		        int count = rnd.nextInt(8);

		        for (int i=1; i<=count; i++) {

		            char specialChar = generateChar(ALL_CHARS);

		            insertAtRandomPosition(password, specialChar);

		        }



		        System.out.println(password);

		    }



		    private static void insertAtRandomPosition(

		            StringBuilder password, char character) {

		        int randomPosition = rnd.nextInt(password.length()+1);

		        password.insert(randomPosition, character);

		    }



		    private static char generateChar(String availableChars) {

		        int randomIndex = rnd.nextInt(availableChars.length());

		        char randomChar = availableChars.charAt(randomIndex);

		        return randomChar;

		    }



	}