java4android (被客户不断变化的需求“折磨”)

父类：

class Printer{
    void open(){
        System.out.print("Open");
    }
    
    void close(){
        System.out.print("close");
    }
    
    void print(String print){
        System.out.print("print-->"+print);
    }
}

子类：

class HPPrinter extends Printer{
    
}

class CanonPrinter extends Printer{
    
    void close(){
        this.clean();
        super.close();
    }
    
    void clean(){
        System.out.print("clean");
    }
}

主函数：

class Test{
    public static void main(String args[]){
        int flag = 0;
        
        if(flag == 0){
            HPPrinter hpPrinter = new HPPrinter();
            hpPrinter.open();
            hpPrinter.print("bvc");
            hpPrinter.close();
        }
        else if(flag == 1){
            CanonPrinter canonPriter = new CanonPrinter();
            canonPriter.open();
            canonPriter.print("bvc");
            canonPriter.close();
        
         }
    }
}