Java Observer Pattern

Speaker.kt

class Speaker() {
    
    private var message= Message("Hello")

    private val audiences = ArrayList<Audience>()


    fun setMessage(msg:String ) {
       this.message.text =  msg
        notifyAudience()
    }
    fun addAudience(audience: Audience){
       audiences.add(audience)
    }

    fun notifyAudience() {
        for ( audience in audiences ) {
            audience.update(message)
        }
    }


}