[Java in NetBeans] Lesson 06. Custom classes
阿新 • • 發佈:2018-12-14
這個課程的參考視訊和圖片來自youtube。
主要學到的知識點有:
- Constructors: A special method called when an object of the class is created
- property pattern and encapsulation(封裝): hide the implementation details from the user, so when the class is been inherited, only the methods, but not the members.
- this: simply refers to the current class.
- Also allow us to call other constructor in one constructor
public class Foo { private int _x; // if class members, and not public, start with underscore. public Foo() { this(1); } public Foo(int x) { _x= x; } }
- Overload: The method with different parameter but same method name. (for example, the constructors. Java will automatic search for the constructors that fits the parameters passed in)
e.g. Foo foo = new Foo(8); will automatic search for the second constructor "public Foo(int x)".
- Every class should have a constructor. But the body can be empty.
- Declare variables as private as possible. Can create getter and setter for the variables to control access to private variables. based on the encapsulation(封裝) concept.
- Initialize all private variables in constructor. (if not, make them final)
- this disambiguates method parameters from private members, but will name the members with _(unless it is public). Below is an example without "_".
public class Foo { private int x; public Foo() { this(1); } public int setX(int x) { this.x = x; } }
- Use get/set methods to control access to private variables.