下面我们通过一个简单的旅行费用计算程序来演示如何使用double占位符来输出浮点数。 publicclassTravelCostCalculator{publicstaticvoidmain(String[]args){doublehotelCostPerNight=100.50;doubleflightCost=500.75;intnumberOfNights=5;doubletotalHotelCost=hotelCostPerNight*numberOfNights;doubletotalCost=totalHotelCost+fligh...