Java 介面實作與應用

Java 介面宣告方式：

public interface Refuel{
  
    //介面的方法，可視為抽象方法！
    public String doRefuel();
}

修改一下原來的 Sedan 類別：

public class Sedan extends Vehicle implements Refuel{

    private char audioClass;
    private double fuelTank;

    Sedan(int wheels, String engineType, double weight, char audio , double fuelTank){
      super(wheels,engineType,weight);
      this.audioClass = audio;
      this.fuelTank = fuelTank;
    }

    //實作抽象方法
     public void ignite(){
       System.out.println("Engine start!");
    }

    //實作介面方的方法
    public String doRefuel(){
      this.fuelTank = 20.00;
      return "Refeuel :" + this.fuelTank;
    }
}

實作 Sedan 類別：

public class Demo {
 public static void main(String[] args){

    Sedan bm = new Sedan(4, "Diesel" , 2231.21 , 'A' , 0.0);
    System.out.println(bm.doRefuel());
    bm.ignite();
 }
}