Java doesn't support multiple inheritance but implicitly every class in java extends Object and allows one more

Your class that extends that other class, but it extends Object, too, so you're still in one line of inheritance, not two.

No. In Java, a class can only inherit from one class and by default this is the Object class that you refer to. We can however specify a different class to inherit from (using the 'extends' keyword). However, this parent class will itself have a parent class and so on until ultimately we get back to the Object class. Perhaps an example will help:

class Animal {
}

class Cat extends Animal {
}

class Tiger extends Cat {
}

In the above example Tiger inherits from Cat which inherits from Animal which (by default) inherits from Object.

Hope this clears things up a touch.