Why doesn't this work?

Eine Zuweisung erflogt mit dem Operator = Wenn du einer Variable einen Wert zuweisen willst, dann musst du erst die Variable bennennen und dann den Wert zu weisen, z.B. int meineZahl = 2. Überlegt dir nochmal was in dieser Aufgabe Variable ist und was der Wert, der übergeben wird.

How do we give a specific age to an already created 'Mann' type object? ('mann' is the Mann-type object.) mann.alter = 62; 'alter' is an int-type variable of 'mann' object, so you can assign to it a value of type int. How do you add a wife to the 'mann' object? The object 'mann' has a variable of type 'Frau', 'ehefrau', and you can assign to it an object of type 'Frau' (for example the created object 'frau'). Exactly the same way you assigned a value to the 'alter'. If two years pass and 'mann' becomes two years older, you can write this in the code: mann.alter = mann.alter + 2; or you could write this: mann.alter = 64; And if 'mann' and 'frau' get divorced and then 'mann' gets married again, you would write this in the code: Frau frau2 = new Frau(); mann.ehefrau = frau2; (this last code line removes the previous wife automatically.)

Lines 11 and 12 are illegal code in many ways. The dot operator refers to a variable or method that belongs to an object. Means, that variable already has to exist and if not, then it has to be defined inside the class (and not inside methods - inside methods you define only local variables and not instance or class variables). So just writing mann.ehefrau; is perfectly valid. That would mean you access the ehefrau variable of the mann object. And it is also perfectly valid to assign a value to that varible like mann.ehefrau = frau; You just can not define that instance variable somewhere outside of its scope.