问题描述
我需要实现一个输入过滤，格式为 1234.35 限制数字输入。也就是说，在此之前最多四个。键，小数点后两位。我用这模式：
I need to implement an input filter for limiting numeral entry in the format 1234.35. That is, maximum four before . and two decimal places. I am using this regular expression pattern:
Pattern.compile("[0-9]{0,4}+((\\.[0-9]{0,2})?)||(\\.)?");
这工作，但一旦我在编辑文本输入号码，并尝试之前，小数编辑值，我无法对其进行编辑。我只能将其删除。
This works, but once I enter a number in the edit text and try to edit the values before the decimal places, I can't edit them. I can only delete them.
什么是错的？
推荐答案
根据您所说的，我认为它看起来像你试图做的，我会用这个普通的前pression：
Based upon what you said and I think it looks like you were trying to do, I would use this regular expression:
^(\d{0,4})(\.\d{1,2})?$
这0-4个数字'匹配带或不带一个小数点和两个号码跟了上去。如果有小数点，那么一个或者两个数字必须遵循它。例如： 5 ， 1234 ， 1234.56 ， 0.2 和 0.31 都是有效的，并由前pression匹配，但 0.123 ， 1234 ， 1234.567 ， 12345 和。不匹配。
It matches '0-4 digits' with or without 'a decimal point and two numbers' following them. If there is a decimal point, then either one or two digits must follow it. For instance: 5, 1234, 1234.56, .2, and .31 are all valid and matched by the expression, but .123, 1234., 1234.567, 12345, and . are NOT matched.
另外，允许数以小数结尾（如。， 1234 ，等），使用这种修改
Alternatively, to allow numbers ending in decimals (like ., 1234., and the like), use this modification:
^(\d{0,4})(\.(\d{1,2})?)?$
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