3.创建两个条件对象，分别对应于用户选择的条件：

final Color color = getColorFromUserInput();

Condition colorCondition = new  Condition {

        public boolean passes(Object o){

        return ((Car)o).getColor().equals(color);

    }

};

final int maxSpeed = getSpeedFromUserInput();

Condition maxSpeedCondition = new Condition {

    public boolean passes(Object o){

        return ((Car)o).getMaxSpeed() >= maxSpeed;

    }

}

然后把这些Condition对象加入一个Condition[]:

Condition[] conditions = new Condition[2];

conditions[0] = colorCondition;

conditions[1] = maxSpeedCondition;

4.创建两个OrderInstruction对象，分别对应于各个排序标准：

//Note: We supply a null Comparator for this OrderInstruction, since

//the default ordering behavior of String suits our purposes.

//We can also reuse the invokers we defined for the SelectInstructions.

OrderInstruction colorOrderInstruction = new  OrderInstruction(colorInvoker, null);

//Note: We supply a custom Comparator for this OrderInstruction, since the

//default ordering behavior of Integer (lower number first) does not suit our purposes.

//We want to show the higher speed at the top! (This corresponds to specifying DESC for order by

//in SQL.)

OrderInstruction speedOrderInstruction = new  OrderInstruction(speedInvoker, new Comparator(){

   public int compare(Object o1, Object o2){

      if(o1 == null && o2 == null)return 0;

      if(o1 == null) return - 1;

      if(o2 == null) return 1;

      //By comparing o2 to o1, we get the opposite order.

      return ((Integer)o2.compareTo(o1);

   }

});

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