overriding

I was wondering, when creating new Activity classes and then overriding the onCreate() method, in eclipse I always get auto added: super.onCreate() . How does this happen? Is there a java keyword in the abstract or parent class that forces this? I don't know if it is illegal not to call the super class, but I remember in some methods that I got a exception thrown for not doing this. Is this also built-in into java? Can you use some keyword to do that? Or how is it done? Here's the source of Activity#onCreate() - it is almost all comments ( original - see line ~800 ): /** * Called when the

I'm working on a web app that has a topBar similar to facebook's blue bar at the top. I have an unordered list within the div of that bar to list some items, like Inbox, Notifications, etc. The UL has a 1em margin as defined by the user agent stylesheet of my browser. This is a problem because it's pushing my topBar down 1em. How can I override this to make the border of the ul = 0? I've read that overriding user agent stylesheets is a bad idea so I'm curious to learn what is best to do. Thanks. EDIT: Here's the CSS file: body { margin:0px; padding:0px; } #topBar{ background-color:#CCCCCC;

I would like to better understand why, in the scenario below, there is a difference in the way class constants are inherited vs. instance variables. <?php class ParentClass { const TEST = "ONE"; protected $test = "ONE"; public function showTest(){ echo self::TEST; echo $this->test; } } class ChildClass extends ParentClass { const TEST = "TWO"; protected $test = "TWO"; public function myTest(){ echo self::TEST; echo $this->test; } } $child = new ChildClass(); $child->myTest(); $child->showTest(); Output: TWO TWO ONE TWO In the code above, ChildClass does not have a showTest() method, so the

Is there a specific rule on how Overriding equals() & hashCode() in sub classes considering super fields ?? knowing that there is many parameters : super fields are private/public , with/without getter ... For instance, Netbeans generated equals() & hashCode() will not consider the super fields ... and new HomoSapiens("M", "80", "1.80", "Cammeron", "VeryHot").equals( new HomoSapiens("F", "50", "1.50", "Cammeron", "VeryHot")) will return true :( public class Hominidae { public String gender; public String weight; public String height; public Hominidae(String gender, String weight, String height

When I make my own Android custom class, I extend its native class. Then when I want to override the base method, I always call super() method, just like I always do in onCreate , onStop , etc. And I thought this is it, as from the very beginning Android team advised us to always call super on every method override. But, in many books I can see that developers, more experienced than myself, often omit calling super and I really doubt they do it as a lack of knowledge. For example, look at this basic SAX parser class where super is omitted in startElement , characters and endElement : public