[Java in NetBeans] Lesson 06. Custom classes

這個課程的參考視頻和圖片來自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.?