Programmier-1-mal-1: Klassen

Klassen sind besonders nutzlich, wenn verschiedene Eigenschaften in gebündelter Form gespeichert/verarbeitet werden sollen.
In ihnen können Daten, sowie Methoden abgelegt werden.

Einfache Klasse Mittel

#include <iostream>
#include <string>

using namespace std;

class Animal {
  public:
    Animal(string latinName) {
      this->latinName = latinName;
    }
    Animal(string latinName, string englishName) {
      this->latinName = latinName;
      this->englishName = englishName;
    }
    string getLatinName() {
      return latinName;
    }
    string getEnglishName() {
      return englishName != null ? englishName : latinName;
    }
    virtual bool canFly() {
      return false;
    }
  private:
    string latinName;
    string englishName = null;
};
int main() {
  Animal squirrel = Animal("Sciuridae", "Squirrel");
  std::cout << squirrel.getEnglishName();

  return 0;
}

public class Main {
  public static class Animal {
    private String latinName;
    private String englishName = null;

    public Animal(String latinName) {
      this.latinName = latinName;
    }
    public Animal(String latinName, String englishName) {
      this(latinName);
      this.englishName = englishName;
    }
    public String getLatinName() {
      return latinName;
    }
    public String getEnglishName() {
      return englishName != null ? englishName : latinName;
    }
    public boolean canFly() {
      return false;
    }
  };

  public static void main(String[] args) {
    Animal squirrel = new Animal("Sciuridae", "Squirrel");
    System.out.println(squirrel.getEnglishName());
  }
}

class Animal:
  def __init__(self, latinName, englishName = None):
    self.latinName = latinName
    self.englishName = englishName
  latinName = None
  englishName = None

  def getLatinName(self):
    return self.latinName
  def getEnglishName(self):
    if (self.englishName != None): return self.englishName
    return self.latinName
  def canFly(self):
    return False

if __name__ == '__main__':
  squirrel = Animal("Sciuridae", "Squirrel");
  print(squirrel.getEnglishName());

Subklasse Fortgeschritten

Durch Subklassen lassen sich Klassen mit zusätzlicher Funktionalität erweitern.

class Bird : public Animal {
  public:
    Bird(string latinName, bool ableToFly) : Animal(latinName) {
      this->ableToFly = ableToFly;
    }
    Bird(string latinName, string englishName, bool ableToFly) : Animal(latinName, englishName) {
      this->ableToFly = ableToFly;
    }
    virtual bool canFly() {
      return ableToFly;
    }
  private:
    bool ableToFly;
};
int main() {
  Animal squirrel = Animal("Sciuridae", "Squirrel");
  cout << squirrel.getEnglishName() << "s " << (squirrel.canFly() ? "can" : "cannot") << " fly" << endl;
  Bird penguin = Bird("Spheniscidae", "Penguin", false);
  cout << penguin.getEnglishName() << "s " << (penguin.canFly() ? "can" : "cannot") << " fly" << endl;
  Bird parrot = Bird("Psittaciformes", "Parrot", true);
  cout << parrot.getEnglishName() << "s " << (parrot.canFly() ? "can" : "cannot") << " fly" << endl;

  return 0;
}

public class Main {
  public static class Bird extends Animal {
    private boolean ableToFly;

    public Bird(String latinName, boolean ableToFly) {
      super(latinName); // Mit 'super' kann auf den Konstruktor, aber auch auf Funktionen der Elternklasse verwiesen werden
      this.ableToFly = ableToFly;
    }
    public Bird(String latinName, String englishName, boolean ableToFly) {
      super(latinName, englishName);
      this.ableToFly = ableToFly;
    }
    @Override
    public boolean canFly() {
      return ableToFly;
    }
  };
  public static void main(String[] args) {
    Animal squirrel = new Animal("Sciuridae", "Squirrel");
    System.out.println(squirrel.getEnglishName() + "s " + (squirrel.canFly() ? "can" : "cannot") + " fly");
    Bird penguin = new Bird("Spheniscidae", "Penguin", false);
    System.out.println(penguin.getEnglishName() + "s " + (penguin.canFly() ? "can" : "cannot") + " fly");
    Bird parrot = new Bird("Psittaciformes", "Parrot", true);
    System.out.println(parrot.getEnglishName() + "s " + (parrot.canFly() ? "can" : "cannot") + " fly");
  }
}

class Bird(Animal):
  def __init__(self, latinName, ableToFly, englishName = None):
    super(Bird, self).__init__(latinName, englishName)
    self.ableToFly = ableToFly
  ableToFly = False

  def canFly(self):
    return self.ableToFly

if __name__ == '__main__':
  squirrel = Animal("Sciuridae", "Squirrel");
  print(f"{squirrel.getEnglishName()}s {"can" if squirrel.canFly() else "cannot"} fly");
  penguin = Bird("Spheniscidae", False, "Penguin");
  print(f"{penguin.getEnglishName()}s {"can" if penguin.canFly() else "cannot"} fly");
  parrot = Bird("Psittaciformes", True, "Parrot");
  print(f"{parrot.getEnglishName()}s {"can" if parrot.canFly() else "cannot"} fly");

Vorherige Lektion

Programmieren mit Schleifen

Nächste Lektion

Herausforderung: Klassen