java中的数字和小数的正则表达式

Question

需要一个允许以下有效值的正则表达式。（只允许使用小数和数字）

有效：

.1  
1.10  
1231313  
0.32131  
31313113.123123123 

无效：

dadadd.31232  
12313jn123  
dshiodah  

Answer 1

如果你想对你允许的比赛严格要求：

^[0-9]*\.?[0-9]+$

<强>解释：

^         # the beginning of the string
 [0-9]*   #  any character of: '0' to '9' (0 or more times)
 \.?      #  '.' (optional)
 [0-9]+   #  any character of: '0' to '9' (1 or more times)
$         # before an optional \n, and the end of the string

Live Demo

Answer 2

试试这个：

String input = "0.32131";

Pattern pat = Pattern.compile("\\d*\\.?\\d+");
Matcher mat = pat.matcher(input);

if (mat.matches())
    System.out.println("Valid!");
else
    System.out.println("Invalid");

Answer 3

您可以尝试使用正则表达式：

^(\d+|\d*\.\d+)$

_{*使用Debuggex: Online visual regex tester生成的图像。}

这个正则表达式的解释：

NODE                     EXPLANATION
--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
   |                        OR
--------------------------------------------------------------------------------
    \d*                      digits (0-9) (0 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
    \.                       '.'
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

_{*来自Explain Regular Expressions的解释。}