Java 如何检查ObservalArray中是否已经存在具有重复LocalDateTime属性的对象？

我编写了一个addAppointmentSaveButtonClick方法，该方法创建了如下对象：

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);

        MainScreenController.appointmentDisplayList.add(newAppointment);

    public static boolean existingAppointment(LocalDateTime ldt) {
    for (Appointment app : appointmentDisplayList) {
        if (app.getStart() == ldt) {
            System.out.println("True");
            return true;
        }
    }
    System.out.println("False");
    return false;
}

if(!existingAppointment(startDateTime)) {
        AppointmentMethods.addAppointment(appointmentType, chosenCustomerId, utcStartTime, utcEndTime);
        appointmentId = AppointmentMethods.getAppointment(chosenCustomerId, utcStartTime).getAppointmentId();

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);
        MainScreenController.appointmentDisplayList.add(newAppointment);}

然后将该对象添加到observableArrayList中，如下所示：

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);

        MainScreenController.appointmentDisplayList.add(newAppointment);

    public static boolean existingAppointment(LocalDateTime ldt) {
    for (Appointment app : appointmentDisplayList) {
        if (app.getStart() == ldt) {
            System.out.println("True");
            return true;
        }
    }
    System.out.println("False");
    return false;
}

if(!existingAppointment(startDateTime)) {
        AppointmentMethods.addAppointment(appointmentType, chosenCustomerId, utcStartTime, utcEndTime);
        appointmentId = AppointmentMethods.getAppointment(chosenCustomerId, utcStartTime).getAppointmentId();

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);
        MainScreenController.appointmentDisplayList.add(newAppointment);}

现在，当我想创建新约会或编辑现有约会时，我想检查appointmentDisplayList数组中是否已经有一个具有相同开始时间的约会

StartDateTime是从组合框菜单中选择的LocalDateTime变量，其格式始终如下：

2020-02-15 10:30:00

以30分钟为间隔，不存在毫秒或类似问题

到目前为止我所做的：

我创建了如下方法，该方法通过appointmentDisplayList进行迭代，如下所示：

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);

        MainScreenController.appointmentDisplayList.add(newAppointment);

    public static boolean existingAppointment(LocalDateTime ldt) {
    for (Appointment app : appointmentDisplayList) {
        if (app.getStart() == ldt) {
            System.out.println("True");
            return true;
        }
    }
    System.out.println("False");
    return false;
}

if(!existingAppointment(startDateTime)) {
        AppointmentMethods.addAppointment(appointmentType, chosenCustomerId, utcStartTime, utcEndTime);
        appointmentId = AppointmentMethods.getAppointment(chosenCustomerId, utcStartTime).getAppointmentId();

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);
        MainScreenController.appointmentDisplayList.add(newAppointment);}

然后，每当单击“保存”按钮时，我都会将对象创建代码放入IF代码块中，如下所示：

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);

        MainScreenController.appointmentDisplayList.add(newAppointment);

    public static boolean existingAppointment(LocalDateTime ldt) {
    for (Appointment app : appointmentDisplayList) {
        if (app.getStart() == ldt) {
            System.out.println("True");
            return true;
        }
    }
    System.out.println("False");
    return false;
}

if(!existingAppointment(startDateTime)) {
        AppointmentMethods.addAppointment(appointmentType, chosenCustomerId, utcStartTime, utcEndTime);
        appointmentId = AppointmentMethods.getAppointment(chosenCustomerId, utcStartTime).getAppointmentId();

        Appointment newAppointment = new Appointment(appointmentId, chosenCustomerId, appointmentType, startDateTime, endDateTime, customerName);
        MainScreenController.appointmentDisplayList.add(newAppointment);}

现在我在代码中遇到的问题是，我为我的新appointent选择的每个时间和日期，这个if块总是为false，并且重复的约会被添加到我的ArrayList中

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我希望任何有经验的程序员都能帮我找出我做错了什么？提前谢谢你

对于对象，

=

测试它们是否是相同的对象。假设设置良好，

.equals（）

测试它们是否具有相同的值。有关设置.equals的详细讨论，请参阅

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这就是为什么需要

app.getStart（）.equals（ldt）

来比较日期值，以查看两个对象是否表示相同的日期

app.getStart（）==ldt

正在检查它们是否是同一个对象，这不是您想要的。

您是否尝试过app.getStart（）.equals（ldt）？您能否将其作为答案发布，以便我可以将其标记为已回答。我还是很难理解为什么它会像你建议的那样工作！非常感谢。