Αντικειμενοστραφής Προγραμματισμός

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====== Εντολές ελέγχου ροής προγράμματος ======

===== if - else if - else statement =====

Ανάλογα με την γλώσσα C. Δείτε το παρακάτω παράδειγμα.
<code java IfElseDemo.java>
class IfElseDemo {
    public static void main(String[] args) {

        int testscore = 76;
        char grade;

        if (testscore >= 90) {
            grade = 'A';
        } else if (testscore >= 80) {
            grade = 'B';
        } else if (testscore >= 70) {
            grade = 'C';
        } else if (testscore >= 60) {
            grade = 'D';
        } else {
            grade = 'F';
        }
        System.out.println("Grade = " + grade);
    }
}
</code>

===== Switch statement =====

Σε αναλογία με την γλώσσα C, η Java υποστηρίζει την εντολή //switch//. Η ιδιαιτερότητα της //switch// στην Java είναι ότι υποστηρίζει ακεραίους, //enumerated types// ή αλφαριθμητικά. Δείτε τα παρακάτω παραδείγματα με χρήση ακεραίων και αλφαριμθητικών.

<code java SwitchDemo.java>
public class SwitchDemo {
    public static void main(String[] args) {

        int month = 8;
        String monthString;
        switch (month) {
            case 1:  monthString = "January";
                     break;
            case 2:  monthString = "February";
                     break;
            case 3:  monthString = "March";
                     break;
            case 4:  monthString = "April";
                     break;
            case 5:  monthString = "May";
                     break;
            case 6:  monthString = "June";
                     break;
            case 7:  monthString = "July";
                     break;
            case 8:  monthString = "August";
                     break;
            case 9:  monthString = "September";
                     break;
            case 10: monthString = "October";
                     break;
            case 11: monthString = "November";
                     break;
            case 12: monthString = "December";
                     break;
            default: monthString = "Invalid month";
                     break;
        }
        System.out.println(monthString);
    }
}
</code>

<code java StringSwitchDemo.java>
public class StringSwitchDemo {

    public static void main(String[] args) {

        String month = "August";
        int monthNumber;

        switch (month) {
            case "January":
                monthNumber = 1;
                break;
            case "February":
                monthNumber = 2;
                break;
            case "March":
                monthNumber = 3;
                break;
            case "April":
                monthNumber = 4;
                break;
            case "May":
                monthNumber = 5;
                break;
            case "June":
                monthNumber = 6;
                break;
            case "July":
                monthNumber = 7;
                break;
            case "August":
                monthNumber = 8;
                break;
            case "September":
                monthNumber = 9;
                break;
            case "October":
                monthNumber = 10;
                break;
            case "November":
                monthNumber = 11;
                break;
            case "December":
                monthNumber = 12;
                break;
            default: 
                monthNumber = 0;
                break;
        }

        System.out.println("Month number: "+monthNumber);
    }
}
</code>


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