将随机 UUID 分配为地图键的问题

Question

我正在制作一个调度（调度员？）程序。当我设法创建“addReport”方法时，我在显示所有报告（遍历地图）时遇到了问题。我认为每次我尝试添加新元素时，它们都会被替换，因为标识符 (UUID) 是相同的。你怎么看，或者可能是不同的东西？

public class Dispatching {
    private String identificator;
    private Map<String, Report> reportMap;

    public Dispatching() {
        this.identificator = UUID.randomUUID().toString();
        this.reportMap = new HashMap<>();
    }

    void addReport(String message, ReportType type) {
        reportMap.put(identificator, new Report(type, message, LocalTime.now()));
    }

    void showReports() {
        for (Map.Entry element : reportMap.entrySet()) {
            System.out.println("uuid: " + element.getKey().toString()
                    + " " + element.getValue().toString());
        }
    }

}

public class Report {
    ReportType reportType;
    String reportMessage;
    LocalTime reportTime;


    public Report(ReportType reportType, String reportMessage, LocalTime reportTime) {
        this.reportType = reportType;
        this.reportMessage = reportMessage;
        this.reportTime = reportTime;

    }

    @Override
    public String toString() {
        return "Report{" +
                "reportType=" + reportType +
                ", reportMessage='" + reportMessage + '\'' +
                ", reportTime=" + reportTime +
                '}';
    }
}

public class Main {

    public static void main(String[] args) {
        Dispatching dispatching = new Dispatching();

        dispatching.addReport("heeeeelp",ReportType.AMBULANCE);
        dispatching.addReport("poliiiice",ReportType.POLICE);
        dispatching.addReport("treeee",ReportType.OTHER);

        dispatching.showReports();

    }



}

public enum ReportType {
    AMBULANCE,
    POLICE,
    FIRE_BRIGADE,
    ACCIDENT,
    OTHER
}

Answer 1

您UUID在构造函数中生成唯一一次并在内部重用它addReport，最终，map 将只保留同一键的最后一个条目，因此使用生成一个新 ID

void addReport(String message, ReportType type) {
        reportMap.put(UUID.randomUUID().toString(), new Report(type, message, LocalTime.now()));
    }