Operatoren und Ausdrücke

public class Rechnen {
    public static void main(String[] args) {
        int a = 17, b = 5;
        System.out.println(a + " + " + b + " = " + (a + b));
        System.out.println(a / b + " Rest " + a % b);
        System.out.println((double) a / b);
        int i = 5;
        System.out.println(i++ + " " + i);     // erst benutzen, dann erhöhen
        System.out.println(++i + " " + i);     // erst erhöhen, dann benutzen
        i += 10; i *= 2;
        System.out.println(i);
        System.out.println(Math.pow(2, 10) + " " + Math.sqrt(144) + " " + Math.abs(-7) + " " + Math.max(3, 9));
        System.out.println(Math.round(2.5) + " " + Math.round(-2.5) + " " + Math.floor(-2.5) + " " + Math.ceil(2.1));
    }
}

public class Logik {
    public static void main(String[] args) {
        int alter = 20;
        boolean hatTicket = true;
        System.out.println(alter >= 18 && hatTicket);
        System.out.println(alter < 18 || hatTicket);
        System.out.println(!hatTicket);
        String status = alter >= 18 ? "volljährig" : "minderjährig";
        System.out.println(status);

        String s = null;
        System.out.println(s != null && s.length() > 3);   // Kurzschluss: kein Fehler
    }
}

public class Bits {
    public static void main(String[] args) {
        int a = 0b1100, b = 0b1010;
        System.out.println((a & b) + " " + (a | b) + " " + (a ^ b) + " " + (~a));
        System.out.println((1 << 4) + " " + (256 >> 2) + " " + (-8 >>> 28));
        System.out.println(Integer.toBinaryString(42) + " " + Integer.toHexString(255) + " " + Integer.bitCount(255));
    }
}

public class Muster {
    public static void main(String[] args) {
        Object o = "Hallo";
        if (o instanceof String s && s.length() > 3) {      // Typ prüfen und gleich benutzen
            System.out.println(s.toUpperCase());
        }
        Object[] dinge = { 42, "Text", 3.5, true };
        for (Object d : dinge) {
            String art = switch (d) {
                case Integer i when i > 10 -> "große Ganzzahl " + i;
                case Integer i -> "Ganzzahl " + i;
                case String t -> "Text der Länge " + t.length();
                default -> "etwas anderes: " + d;
            };
            System.out.println(art);
        }
    }
}

public class Ueberlauf {
    public static void main(String[] args) {
        int max = Integer.MAX_VALUE;
        System.out.println(max + 1);                          // springt auf Minimum
        try {
            Math.addExact(max, 1);                            // wirft stattdessen eine Ausnahme
        } catch (ArithmeticException e) {
            System.out.println(e.getMessage());
        }
        System.out.println(5 / 2.0 + " " + 1.0 / 0 + " " + 0.0 / 0);
        try { System.out.println(5 / 0); } catch (ArithmeticException e) { System.out.println(e.getMessage()); }
    }
}