Continuation of DSC 30 Lecture 1
Documenting your code with Javadoc
class SmallerFunction {
/** Returns the smaller of the two */
public static int smaller(int x, int y) {
if (x < y) {
return x;
}
return y;
}
} For Loop in Java
for (int i=0; i<10; i++) {
// Loop statement to be executed
} Reflections on Static Typing
The Good:
- Debugging is a lot easier, type errors are avoided.
- Code on the user side has no type errors, which means phones won’t crash because of type errors.
- Programs run more efficiently in time and memory.
- Self-documenting: YOU KNOW WHAT YOU’VE GOT
The Bad:
- Code is more verbose.
- Code is less general. There is a way around this in Java (Generics)
Source: https://docs.google.com/presentation/d/1dhz8i4x4Q89OnVy5K6I-95i7pxSX4UWy/edit#slide=id.p1
Classes and Objects
Classes
- Constructor - how to set up your object when it’s created
- State (instance variables) - what describes your object (variables)
- Behaviors - what your object can do (methods)
Object Instantiation
- Classes can be instantiated as objects.
- We’ll create a single Car class, and then create instances of this class.
- The class provides a blueprint that all Car objects will follow.
- By storing different data in instance variables.
- Defining different behaviors in methods.
Defining a Typical Class (Terminology)
Instance Variable. Can have as many of these as you want.
Constructor (similar to a method, but not a method). Determines how to instantiate the class. Has the same name as a class.
Non-static method, a.k.a. Instance Method. Idea: If the method is going to be invoked by an instance of the class (as in the static slide), then it should be non-static.
Roughly speaking: If the method needs to use “my instance variables”, the method must be non-static.