如何从getters检查用户输入和字段

Question

 public void chooseFlight(ArrayList<Flight> flightList) {
    System.out.println("Choose flight by ID: ");
    int pickedFlight = scanner.nextInt();
    scanner.nextLine();

    for (Flight tempFlight : flightList) {
        if (pickedFlight == tempFlight.getId()) {
            System.out.println("You picked flight from: " + tempFlight.getFrom() + ", to "
                    + tempFlight.getTo() + ". Prices are: | Economic class: "
                    + tempFlight.getPriceForEconomicClass() + " | Business class : "
                    + tempFlight.getPriceForBusinessClass() + " | First class: "
                    + tempFlight.getPriceForFirstClass());
            selectedFlight = tempFlight;
            break;
        } else {
            System.out.println("Flight ID doesnt exist");
        }
        System.exit(0);
    }
}

我就是这样保存航班的：

Flight flight1 = new Flight(1, "Moscow", "Belgrade", 300, 600, 850, "gC49");
    Flight flight2 = new Flight(2, "Paris", "Dortmund", 250, 290, 400, "soe4");
    Flight flight3 = new Flight(3, "Podgorica", "Nis", 25, 40, 80, "sx33");
    Flight flight4 = new Flight(4, "London", "Miami", 600, 1500, 2500, "zcl3");

ArrayList<Flight> flightsArrayList = new ArrayList<>();
    flightsArrayList.add(flight1);
    flightsArrayList.add(flight2);
    flightsArrayList.add(flight3);
    flightsArrayList.add(flight4);

运行上面的第一个方法后的输出是如果我输入了除1号以外的任何ID

航班ID不存在尽管我输入了与航班ID匹配的ID。

} else {
            System.out.println("Flight ID doesnt exist");
        }
        System.exit(0);

程序运行良好，我只是不知道哪里是我的错误。

Answer 1

for (Flight tempFlight : flightList) {
        if (pickedFlight == tempFlight.getId()) {
            System.out.println("You picked flight from: " + tempFlight.getFrom() + ", to "
                    + tempFlight.getTo() + ". Prices are: | Economic class: "
                    + tempFlight.getPriceForEconomicClass() + " | Business class : "
                    + tempFlight.getPriceForBusinessClass() + " | First class: "
                    + tempFlight.getPriceForFirstClass());
            selectedFlight = tempFlight;
            break;
        } else {
            System.out.println("Flight ID doesnt exist");
        }
        System.exit(0);
    }

您的问题似乎是一个范围问题：

对于您检查的每个元素，如果没有找到，则打印该消息，在循环结束时，您调用system.exit(0)；，这意味着您只检查列表的第一个元素。

您需要执行以下操作：

boolean found = false;
for (Flight tempFlight : flightList) {
        if (pickedFlight == tempFlight.getId()) {
            System.out.println("You picked flight from: " + tempFlight.getFrom() + ", to "
                    + tempFlight.getTo() + ". Prices are: | Economic class: "
                    + tempFlight.getPriceForEconomicClass() + " | Business class : "
                    + tempFlight.getPriceForBusinessClass() + " | First class: "
                    + tempFlight.getPriceForFirstClass());
            found = true;
            break;
        }
    } // this ends the for loop

if ( found ) {
  // you actually found the Flight
} else {
            System.out.println("Flight ID doesnt exist");
        }
        System.exit(0);

Flight found = null;
for (Flight tempFlight : flightList) {
        if (pickedFlight == tempFlight.getId()) {
            System.out.println("You picked flight from: " + tempFlight.getFrom() + ", to "
                    + tempFlight.getTo() + ". Prices are: | Economic class: "
                    + tempFlight.getPriceForEconomicClass() + " | Business class : "
                    + tempFlight.getPriceForBusinessClass() + " | First class: "
                    + tempFlight.getPriceForFirstClass());
            Flight = tempFlight;
            break;
        }
    } // this ends the for loop

if ( found != null ) {
  // you actually found the Flight
} else {
            System.out.println("Flight ID doesnt exist");
        }
        System.exit(0);