java：接口实例

接口：打印机接口

interface Printer

{

    public void read();

}

函数一：佳能打印机

class CanPrinter implements Printer

{

    public void read(){

        System.out.println("Canread");

    };

}

函数二：惠普打印机

class HPPrinter implements Printer

{

    public void read(){

        System.out.println("HPread");

    };

}

主函数：

class Test

{

    public static void main(String args[]){

        int flag=0;

        Printer p = null;

        if(flag==0){

            p = new HPPrinter();

        }else{

            p = new CanPrinter();

        }

    

        p.read();

    }

}

得出：HPread

 

二次整合

接口、函数一、二不变，增加判断flag的类，方便修改

class PrinterFactory

{

    Printer getPrinter(int flag){        //定义类型为Printer

        Printer p = null;

        if(flag==0){

            p = new HPPrinter();

        }else if(flag==1){

            p = new CanPrinter();

        }

        return p;    //返回对象

    }

}

主函数：

class Test

{

    public static void main(String args[]){

        int flag=0;

        PrinterFactory f = new PrinterFactory();

        Printer printer = f.getPrinter(flag);

        printer.read();

    }

}