java - 关于不可变的类完成功能

我正在上一门不变的课。下面是我的不可变类，请告诉我它是完全不可变的，或者如果我缺少某些东西，或者它的不可变性可以通过任何方式分解，那么请告知。

public final class ImmutableReminder{
    private final Date remindingDate;

    public ImmutableReminder (Date remindingDate) {
        if(remindingDate.getTime() < System.currentTimeMillis()){
            throw new IllegalArgumentException("Can not set reminder” +
                        “ for past time: " + remindingDate);
        }
        this.remindingDate = new Date(remindingDate.getTime());
    }

    public Date getRemindingDate() {
        return (Date) remindingDate.clone();
    }
}

最佳答案

在根据您的类不变式检查它之前，您应该制作一个hintingDate.getTime（）的副本。否则，引用您的hintingDate的攻击者可以在检查其有效性之后对其调用.set方法来更改该值。

很长的时间= hintingDate.getTime（）;

public final class ImmutableReminder{
    private final Date remindingDate;

    public ImmutableReminder (Date remindingDate) {
        long incomingTime = remindingDate.getTime()

        if(incomingTime < System.currentTimeMillis()){
            throw new IllegalArgumentException("Can not set reminder” +
                        “ for past time: " + remindingDate);
        }
        this.remindingDate = new Date(incomingTime);
    }

    public Date getRemindingDate() {
        return (Date) remindingDate.clone();
    }
}