Expact with an amstaff

I assume you mean an American Staffordshire Terrier?
Import of this dog race into Germany is forbidden by law.
See https://de.wikipedia.org/wiki/American_ … re_Terrier

In general one has a right to have pets like dogs and cats In Germany and landlords are not allowed to disallow them except on a individual basis where they would have to bring a court case and show that they are a nuisance, dangerous or possibly that they have an allergy against them.

As Beppi wrote, in Germany, there is a law outlawing the import of such breeds because they are considered dangerous. The thinking on this subject has evolved in many communities world-wide over the years to recognize that while such dogs are dangerous if trained to be aggressive or mishandled, they are not inherently a danger. The German laws have been slow to reflect this but are in change as reflected that, as mentioned on the link Beppi provided, Thuringen, Niedesachsen and Schleswig-Holstein have eliminated such a “list of dangerous breeds”.

So it depends on what region in Germany you live in. There are such dogs already in Germany and they are expected to wear a muzzle in public to protect people. Even if they would not bite, just being big and acting in what some might consider an aggressive nature is enough to make trouble if they are not muzzled. And if someone gets bitten by such a dog then expect to face some serious legal problems.

In Thüringen, Niedersachsen and Schleswig-Holstein it is allowed to own such breeds, but it is still not allowed to import them from outside Germany.
And, contrary to what Tom said above, landlords can (and most will) disallow big dogs in their premises - only small ones cannot be forbidden.