amna_treci.java

/*
    Aufgabe 3) Verschachtelung von Schleifen und Methoden - Fröhliche Zahlen
*/
public class Aufgabe3 {
    private static boolean isHappyNumber(int number) {


        //Calculates the sum of squares of digits
        while(number > 0){
        number = sumSqareDig(number);
        if (number== 1) {
            return true;
        }
        }
         return false;          //Zeile kann geändert oder entfernt werden.
    }

    private static int sumSqareDig(int numb) {
        int sum = 0;

        while (numb > 0) {
            sum += (numb%10) * (numb%10);
            numb = numb / 10;
        }
        return sum;
    }

    private static int countHappyNumbers(int start, int end) {
        int counter = 0;
        if (!((start > 0) && (end > 0)) || !(start <= end)) {
            return -1;
        }
        else  {
            for (;start <= end; start++) {
                if (sumSqareDig(start) == 1) {
                    counter++;
                }
            }
        }
        return counter;              //Zeile kann geändert oder entfernt werden.
    }

    private static void printHappyNumbers(int start, int end) {
        if (!((start > 0) && (end > 0)) || !(start <= end)) {
            return;
        }
        else  {
            for (;start <= end; start++) {
                if (sumSqareDig(start) == 1) {
                    System.out.println(start);
                }
            }
        }
    }

    public static void main(String[] args) {
        //DIE NACHFOLGENDEN ZEILEN SIND ZUM TESTEN DER METHODE isHappyNumber(...).

        System.out.println(countHappyNumbers(1,100));
        printHappyNumbers(1,100);

        System.out.println("23 --> " + isHappyNumber(23));
        assert (isHappyNumber(23));
        System.out.println("97 --> " + isHappyNumber(97));
        assert (isHappyNumber(97));
        System.out.println("7 --> " + isHappyNumber(7));
        assert (isHappyNumber(7));
        //assert (isHappyNumber(1));
        System.out.println("58 --> " + isHappyNumber(58));
        assert (!isHappyNumber(58));
        System.out.println("40 --> " + isHappyNumber(40));
        assert (!isHappyNumber(40));
        System.out.println("5 --> " + isHappyNumber(5));
        assert (!isHappyNumber(5));
        assert (!isHappyNumber(4));
        System.out.println();
        //**********************************************************************


        //TODO: Testen Sie hier alle Methoden mit verschiedenen Inputs!
    }
}