Scala技术点——多态性质的动态绑定问题

• scala是单继承语言
• scala的多态性实现方式与Java中基本相同（基于引用类型与实际对象类型的差异性实现多态性）
• Java的动态绑定只是方法的动态绑定
• Scala的动态绑定不仅包括方法还包括属性的动态绑定

Java实现：

class Person {
    public String name = "Person";
    public void show() {
    	system.out.println("I am a Person")
    }
}

class Teacher extends Person {
	public String name = "Teacher";
	@Override
	public void show() {
		system.out.println("I am a Teacher");
	}
}

public class Test {
	public static void main(String[] args) {
		Teacher t0 = new Teacher();
		Person t1 = new Teacher();
		sout(t0.name); // Teacher
		t0.show(); // I am a Teacher
		sout(t1.name); // Person  // 属性并没有动态绑定
		t1.show(); // I am a Teacher
	}
}

Scala实现:

class Person {
	val name: String = "Person"
	def show() : Unit = {
		println("I am a Person")
	}
}

class Teacher extends Person {
	override val name: String = "Teacher"
	override def show(): Unit = {
		println("I am a Teacher")
	}
}

object Test {
	def main(args: Array[String]): Unit = {
		val Teacher t0 = new Teacher()
		println(t0.name)  // Teacher
		t0.show();  // I am a Teacher

		val Person t1 = new Teacher()
		println(t1.name) // Teacher  // 实现了属性的动态绑定
		t1.show(); // I am  a Teacher
	}
}