java 使用前导零将字符串解析为 long
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Parse String to long with leading zero
提问by Tony
Long story short (in Java):
长话短说（Java）：
String input= "0888880747;
long convert = Long.parseLong(input);
The value of convert is now: 888880747
转换的值现在是：888880747
How can I parse the Stringto a longbut retain the leading zero?
如何String将 a解析为 along但保留前导零？
回答by middus
You cannot because a long does not have a leading zero. A long is supposed to store integers (the mathematical concept, not int), i.e.
你不能，因为 long 没有前导零。一个 long 应该存储整数（数学概念，不是int），即
A string of characters like 05is not an integer, 5is. What you can do is format a long that holds 5with a leading zero when you print it, see e.g. java.util.Formatter.
一串字符像05不是整数，5是。您可以做的是5在打印时格式化带有前导零的 long ，参见例如java.util.Formatter。
Are you sure you even want to have a long/an integer? What do you want to do with it?
你确定你甚至想要一个长/整数吗？你想用它做什么？
回答by JonnyKash
You'll have to change it back to a Stringwhen you've done your calculations on convert, then:
String在完成转换计算后，您必须将其改回 a ，然后：
output = String.format("%06d", convert);
回答by Joachim Sauer
A longis a numeric value. The numeric value of 000001 is no different from 1: It's the exact same number.
Along是一个数值。000001 的数值与 1 没有区别：它是完全相同的数字。
So you can'tfind out how many leading zeroes the initial representation had, once you have a long.
所以，你不能找出多少前导零初始表示过，一旦你有一个long。
And ifyou really care about that, then you shouldn't handle the input as a numeric type anyway, but store the Stringitself, instead.
而且，如果你真的关心这一点，那么你不应该处理输入的数字类型无论如何，但存储String本身，而不是。
回答by pcalcao
If your value is a long, then any zeroes to the left (leading) have no mathematical value, therefore, they are stripped off when you do the parsing.
如果您的值是 long，则左侧（前导）的任何零都没有数学价值，因此，在您进行解析时，它们会被剥离。
