是什么在Android的code长，长有什么区别？ [英] What is the difference between long and Long in android code?

问题描述

我试图写一个Android应用程序的AsycTask。在那里，我遇到了整数和长数据类型，我不知道它们是什么。我试着用长在龙，但我得到了日食一个错误说

 令牌长语法错误，尺寸此令牌后，预计。
 

解决方案

龙是一类。长是一种原始。这意味着龙可以为空，在这里长不了。龙可以去任何地方，它接受一个对象，久不能（因为它不是它不会从Object派生类）。

Java的通常翻译一个长成一个长自动（反之亦然），但不会为空值（因为长期不能是长），你需要的时候，你需要通过使用长版本一类（如在通用声明）。

I was trying to write an AsycTask in an android application. There I came across Integer and Long data types and I am not sure what they are. I tried using long in place Long, but I got an error in eclipse saying

'Syntax error on token "long", Dimensions expected after this token'.

解决方案

Long is a class. long is a primitive. That means Long can be null, where long can't. Long can go anywhere that takes an Object, long can't (since it isn't a class it doesn't derive from Object).

Java will usually translate a Long into a long automatically (and vice versa), but won't for nulls (since a long can't be a long), and you need to use the Long version when you need to pass a class (such as in a generic declaration).

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