如何在java中找到两个时间戳的差异?

问题描述

我有一个 ArrayList 包括几个时间戳，目的是找到 ArrayList 的第一个和最后一个元素的差异.

I have an ArrayList including several number of time-stamps and the aim is finding the difference of the first and the last elements of the ArrayList.

String a = ArrayList.get(0);
String b = ArrayList.get(ArrayList.size()-1);
long diff = b.getTime() - a.getTime();

我也将类型转换为 int 但它仍然给我一个错误 getTime 方法未定义为 String 类型.

I also converted the types to int but still it gives me an error The method getTime is undefined for the type String.

附加信息:

我有一个 A 类，其中包括

I have a class A which includes

String timeStamp = new SimpleDateFormat("ss S").format(new Date());

并且有一个 B 类，它有一个方法 private void dialogDuration(String timeStamp)

and there is a class B which has a method private void dialogDuration(String timeStamp)

和 dialogueDuration 方法包括:

String a = timeSt.get(0); // timeSt  is an ArrayList which includes all the timeStamps
String b = timeSt.get(timeSt.size()-1);   // This method aims finding the difference of the first and the last elements(timestamps) of the ArrayList  (in seconds)

long i = Long.parseLong(a);
long j = Long.parseLong(b);

long diff = j.getTime()- i.getTime();

System.out.println("a: " +i);
System.out.println("b: " +j);

并且一个条件是语句(String timeStamp = new SimpleDateFormat("ss S").format(new Date());) 在类 A 中不会被改变.并且一个对象类 B 在类 A 中创建，以便它调用 dialogueDuration(timeStamp) 方法并将时间戳的值传递给类 B.

And one condition is that the statement(String timeStamp = new SimpleDateFormat("ss S").format(new Date());) wont be changed in class A. And an object of class B is created in class A so that it invokes the dialogueDuration(timeStamp) method and passes the values of time-stamps to class B.

我的问题是这个减法不起作用，它给出了一个错误cannot invoke getTime() method on the original type long.对于 int 和 String 类型，它也给出了同样的错误?

My problem is this subtraction does not work, it gives an error cannot invoke getTime() method on the primitive type long. It gives the same kind of error also for int and String types?

非常感谢！

推荐答案

可能是这样的:

SimpleDateFormat dateFormat = new SimpleDateFormat("ss S");
Date firstParsedDate = dateFormat.parse(a);
Date secondParsedDate = dateFormat.parse(b);
long diff = secondParsedDate.getTime() - firstParsedDate.getTime();

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