15. 类及其成员的可见性

Kotlin

类及其成员的可见性

class Countyard {
    val house: House = House();// 默认是public的，java默认是default
    private val flower: Flower = Flower(); // 不可见，只在本class中可见
    internal val flower2:Flower = Flower();// 在本module中可见
    protected val flower3: Flower = Flower();
}

Kotlin	Java
private	private
protected	protected
-	default(包内可见)
internal	-
public	public

object

class Driver

interface OnExternalDriverMountListener {

    fun onMount(driver: Driver);

    fun onUnmount(driver: Driver);

}

abstract class Player

object MusicPlayer : Player(), OnExternalDriverMountListener {

    val state: Int = 0;

    fun play(url: String) {

    }

    fun stop() {

    }

    override fun onMount(driver: Driver) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun onUnmount(driver: Driver) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

}

• 只有一个实例的类
• 不能自定义构造方法
• 可以实现接口，继承父类
• 本质上就是单例模式最基本的实现