Arraylist 中每個項目的嵌套 For-each 循環打印

Question

如何修改此代碼，使其僅在首先遍歷整個列表后才打印出無效消息。 我目前的問題是每次沒有匹配時它都會打印出這些消息。 這不是我打算做的。

public void assignSchedule(Depot depotName) throws Exception {
        String client, driver;
        Boolean exit = false;

        do {
            System.out.printf("%-10s %-10s %10s %n", "Client", "Start Date", "End Date");
            depotName.listWorkSchedulue();
            System.out.print("Enter the client name for the schedule you wish to assign: ");
            client = DepotSystem.input.nextLine();

            for (WorkSchedule ws : depotName.getWorkSchedules())
            {
                if (client.equals(ws.getClient()))
                {
                    System.out.printf("%n%20s%n", "Drivers");
                    depotName.listDrivers();
                    System.out.print("Which Driver do you want to assign this to: ");
                    driver = DepotSystem.input.nextLine();

                    for (Driver drivers : depotName.getDrivers())
                    {
                        if (driver.equals(drivers.userName) && !drivers.assigned)
                        {
                            System.out.printf("%nThe work schedule for client %s is now assigned to %s%n ", client,
                                driver);
                            depotName.getDriver(driver).setSchedule(depotName.getWorkSchedule(client));
                            drivers.setAssigned(true);
                            exit = true;
                        } else if ((!driver.equals(drivers.userName) && drivers.assigned)) {
                            System.out.printf("%nEither not a valid driver or Driver is already assigned a Job.%n");
                        }
                    }
                } else if (!client.equals(ws.getClient())) {
                    System.out.printf("%nPlease enter a valid client.%n");
                }
            }
        } while (!exit);
    }

當前的 output if I enter a Incorrect name 如下

Client     Start Date   End Date 
Gary       2020-04-25   2020-04-27
Bob        2020-05-05   2020-05-06
Enter the client name for the schedule you wish to assign: f

Please enter a valid client.

Please enter a valid client.

當我輸入錯誤的名稱時，這就是我希望它工作的方式。

Client     Start Date   End Date 
Gary       2020-04-25   2020-04-27
Bob        2020-05-05   2020-05-06
Enter the client name for the schedule you wish to assign: f

Please enter a valid client.

Answer 1

在 for 循環的頂部，您可以執行以下操作來確定是否有任何工作計划包含輸入的客戶。 您隨后可以用 clientSchedules 替換depotName.getWorkSchedules()並刪除條件if (client.equals(ws.getClient()))因為我們知道它們都是具有相同客戶端的計划。

請注意，該問題不包含完整的 SSCCE，缺少許多編譯所需的基本類，因此可能會出現意外的編譯錯誤。

            List<WorkSchedule> clientSchedules = depotName.getWorkSchedules().stream()
                            .filter(schedule -> client.equals(schedule.getClient()))
                            .collect(Collectors.toList());

            if (clientSchedules.isEmpty()) {
                System.out.printf("%nPlease enter a valid client.%n");
                continue;
            }

Answer 2

消息， Please enter a valid client應該打印在for循環之外。 執行以下操作：

public void assignSchedule(Depot depotName) throws Exception {
    String client, driver;
    Boolean exit = false, validClient;

    do {
        System.out.printf("%-10s %-10s %10s %n", "Client", "Start Date", "End Date");
        depotName.listWorkSchedulue();
        System.out.print("Enter the client name for the schedule you wish to assign: ");
        client = DepotSystem.input.nextLine();

        for (WorkSchedule ws : depotName.getWorkSchedules()) {
            if (client.equals(ws.getClient())) {
                validClient = true;
                System.out.printf("%n%20s%n", "Drivers");
                depotName.listDrivers();
                System.out.print("Which Driver do you want to assign this to: ");
                driver = DepotSystem.input.nextLine();

                for (Driver drivers : depotName.getDrivers()) {
                    if (driver.equals(drivers.userName) && !drivers.assigned) {
                        System.out.printf("%nThe work schedule for client %s is now assigned to %s%n ", client,
                                driver);
                        depotName.getDriver(driver).setSchedule(depotName.getWorkSchedule(client));
                        drivers.setAssigned(true);
                        exit = true;
                    } else if ((!driver.equals(drivers.userName) && drivers.assigned)) {
                        System.out.printf("%nEither not a valid driver or Driver is already assigned a Job.%n");
                    }
                }
            } else {
                validClient = false;
            }
        }
        if (!validClient) {
            System.out.printf("%nPlease enter a valid client.%n");
        }
    } while (!exit);
}

Answer 3

在循環外聲明一個 boolean 並將其設置為 else if 條件，並在 else if 中檢查此 boolean，例如

 else if (condition && !booleanVariable) {
          System.out.printf("%nPlease enter a valid client.%n");
           booleanVariable = true;
           }