Some Mysteries of objectdraw, Explained

Some Mysteries of objectdraw, Explained

Today, we are going to resolve some mysteries about Java and the code that you have been writing this semester. Here are some questions that should bother you:

• When writing methods in a WindowController, why can you refer to "canvas" without declaring it, but you have to pass the canvas explicitly as a parameter to other classes?
• Usually when we call methods that we have not defined in our class, we say someObject.someMethod(). There are some exceptions to this rule: getImage, pause, etc. Why don't we need to include an object?
• When we write a method call, normally the next code to execute is within that method. However, when we are writing an ActiveObject, we call start and the method named run is executed. Why don't these names match?
• We saw a bit about implements, what about extends?

Some Mysteries of objectdraw, Explained