回调函数

/**
 * @author LiosWong
 * @description 工具接口
 * @date 2018/6/23 上午1:03
 */
public interface Tools {
    /**
     * 打电话
     * @param msg
     * @return
     */
    String getCallMsg(String msg);
}

/**
 * @author LiosWong
 * @description 顾客类
 * @date 2018/6/23 上午1:01
 */
public class Customer implements Tools{
    @Override
    public String getCallMsg(String msg) {
        if(StringUtils.isNotEmpty(msg)){
            System.out.println(msg);
            return "已收到电话";
        }
        return "";
    }
    public static void main(String[] args) {
        Customer customer = new Customer();
        SalesPerson salesPerson = new SalesPerson();
        salesPerson.callCustomer("ok",customer);
    }
}

/**
 * @author LiosWong
 * @description 售货员
 * @date 2018/6/23 上午1:01
 */
public class SalesPerson {
    public void callCustomer(String msg,Tools tools){
        if("ok".equals(msg)){
            String response = tools.getMsg("已经到货啦,请前来购买～");
            System.out.println(response);
        }
    }
}