正则表达式

一些好的学习资源：

Microsoft MSDN

Java

http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

others

http://developer.51cto.com/art/200912/166310.htm

http://luolei.org/2013/09/regula-expression-simple-tutorial/

http://net.tutsplus.com/tutorials/php/regular-expressions-for-dummies-screencast-series/

http://deerchao.net/tutorials/regex/regex.htm

1. Valid Numbers

Validate if a given string is numeric.

Some examples:
"0"=>true
" 0.1 "=>"abc"=>false
"1 a"=>"2e10"=>true

Note:It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

public boolean isNumber(String s) {
        if(s.trim().isEmpty())
        	return false;
        String regex = "[-+]?(\\d+\\.?|\\.\\d+)\\d*(e[-+]?\\d+)?";
        if(s.trim().matches(regex))
        	return true;
        else
        	return false;
    }