如何打印界面的方法

Question

如何打印接口的连接方法？我只想通过最小化类修改来修改主电源。

如果我使用arr[0].连接（）;错误：未为设备类型定义连接（）方法

public class main{

    private static Device arr[];

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        init();

        arr[0].print();

        arr[1].print();

    }

    public static void init() {

        arr = new Device[2];

        arr[0] = new Printer();

        arr[1] = new UsbMem();

    }

}

public interface Connectable {

    public static final String name = ":USB";

    public abstract void connect();

}

public abstract class Device {

    public abstract void print();

}

public class Printer extends Device implements Connectable {

    public void print() {

        System.out.println("It's a printer");

    }

    public void connect() {

        System.out.println(name + "connect with printer");

    }

}

public class UsbMem extends Device implements Connectable {

    public void print() {

        System.out.println("USB memory");

    }

    public void connect() {

        System.out.println(name + "connect with usb memory");

    }

}

这是一台打印机。：USB 与打印机连接 USB 存储器 ：USB 与 USB 存储器连接

Answer 1

Device需要实现 。Connectablepublic class Main {    private static Device arr[];    public static void main(String[] args) {        // TODO Auto-generated method stub        init();        arr[0].print();        arr[1].print();    }    public static void init() {        arr = new Device[2];        arr[0] = new Printer();        arr[1] = new UsbMem();    }}public interface Connectable {    public static final String name = ":USB";    public abstract void connect();}public abstract class Device implements Connectable {    public abstract void print();}public class Printer extends Device {    public void print() {        System.out.println("It's a printer");    }    public void connect() {        System.out.println(name + "connect with printer");    }}public class UsbMem extends Device {    public void print() {        System.out.println("USB memory");    }    public void connect() {        System.out.println(name + "connect with usb memory");    }}

Answer 2

将对象强制转换为可连接对象((Connectable)arr[0]).connect()