class People {     
    var name: String;    
    var age: Integer;    
}
class Hello {    
    var people: People;  
    function Greeting() {        
        println("Hello {people.name} ,You are {people.age} years old.");    
    }    
}

interface IHello{
    void Greeting();
}

class Man extends People{
    var sex:Boolean;

} 
2、從抽象類或者接口繼承，也用 extends 關(guān)鍵字，接口中的方法必須重載，用 override 關(guān)鍵字 
class Hello  extends IHello{
    var people: People;
    override function Greeting():Void {
        println("Hello {people.name} ,You are {people.age} years old.");
    }
}
3、JavaFX 可以多重繼承，即繼承多個(gè)類和多個(gè)接口 
 
三、對(duì)象的創(chuàng)建
JavaFX 一般用字面量方式創(chuàng)建對(duì)象，也可以用 new 例如

var p = new People(); 
或者
var p = People{
    name:"小明"
    age:18
}

四、對(duì)象的初始化
1、JavaFX 的類沒有構(gòu)造函數(shù)，但是有一個(gè) init 初始化塊，當(dāng)對(duì)象創(chuàng)建以后會(huì)運(yùn)行這個(gè)塊里的代碼，例如
class People {
    init {
        name="Jone";
        println("Hello {name} ,You are {age} years old.");
    }
    var name: String;
    var age: Integer;    
}
var p =  new People();

輸出：Hello Jone ,You are 0 years old.
2、還有一個(gè) postinit 塊，在所有初始化工作完成以后執(zhí)行
3、isInitialized 函數(shù)，判斷一個(gè)成員是否被初始化了，例如
class People {
    var name: String;
    var age: Integer; 
    init {

    //檢查 name 是否被初始化        
        if (isInitialized(name)){
            println("Hello {name}.");
        }else {
            println("What's your name?");
        }
    }  
}

//創(chuàng)建對(duì)象的時(shí)候初始化 name

var p = People{
name: "Jone"
}

輸出：Hello Jone.


//創(chuàng)建對(duì)象的時(shí)候沒有初始化 name
var p = People{
    age: 18
}
輸出：What's your name? 

五、包
和 Java 的用法完全一樣
package 關(guān)鍵字
import 關(guān)鍵字