public abstract class CashSuper {
  public abstract double acceptCash(double money);
}

public class CashNormal extends CashSuper {
 
  @Override
  public double acceptCash(double money) {
    return money;
  }
 
}

/**打折子类
 * 获取打折折扣，使用应付金额乘以折扣
 * @author 我不是张英俊
 *
 */
public class CashRebate extends CashSuper {

  private double moneyRebate=1;
  
  public CashRebate(String moneyRebate){
    this.moneyRebate=Double.parseDouble(moneyRebate);
  }
  @Override
  public double acceptCash(double money) {
    
    
    return money*moneyRebate;
  }

}

/**返利收费子类,例如，满三百减一百
 * @author 我不是张英俊
 *
 */
public class CashReturn extends CashSuper {

  /**
   * 返利收费，初始化时必须要输入返利条件和返利值，比如慢300时返100，
   * 则moneyCondition为300，moneyRetrun 为100
   */
  private double moneyCondition=0;
  private double moneyReturn=0;
  
  public CashReturn(String moneyCondition,String moneyReturn){
    this.moneyCondition=Double.parseDouble(moneyCondition);
    this.moneyReturn=Double.parseDouble(moneyReturn);
  }
  
  
  @Override
  public double acceptCash(double money) {
    
    double result=money;
    if(money>=moneyCondition){
      result=money-Math.floor(money/moneyCondition)*moneyReturn;
    }
    
    return result;
  }

}

/**
 *正常收费的，原价返回
 * @author 我不是张英俊
 *
 */
public class CashNormal extends CashSuper {

  @Override
  public double acceptCash(double money) {
    return money;
  }

}

public class CashContext {

  private CashSuper cs=null;
  
  public CashContext(String type){
    switch (type) {
    case "正常收费":
      CashNormal cs0=new CashNormal();
      cs=cs0;
      break;
    case "满300返100":
      CashReturn cr1=new CashReturn("300", "100");
      cs=cr1;
      break;
    case "打八折":
      CashRebate cr2=new CashRebate("0.8");
      cs=cr2;
      break;
      
    }
  }
  
  public double GetResult(double money){
    return cs.acceptCash(money);
  }
  
}

public class Test {

  public static void main(String[] args) {
    
    double a=new CashContext("打八折").GetResult(300);
    System.out.println(a);
    double b=new CashContext("正常收费").GetResult(300);
    System.out.println(b);
    double c=new CashContext("满300返100").GetResult(300);
    System.out.println(c);
  }

}