模拟图书馆管理系统 实现了各种图书馆管理功能

				import java.lang.*;
				import java.util.regex.*;
				public class IsFloat {
				 public static boolean isFloat(String arg){
					 final String Digits     = "(\\p{Digit}+)";
					 final String HexDigits  = "(\\p{XDigit}+)";
					 final String Exp        = "[eE][+-]?"+Digits;
					 final String fpRegex    =
					            ("[\\x00-\\x20]*"+// Optional leading "whitespace"
					             "[+-]?(" +       // Optional sign character
					             "NaN|" +         // "NaN" string
					             "Infinity|" +    // "Infinity" string
					             "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
				
					             "(\\.("+Digits+")("+Exp+")?)|"+
				
					       "((" +
					        "(0[xX]" + HexDigits + "(\\.)?)|" +
					        "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
				
					        ")[pP][+-]?" + Digits + "))" +
					             "[fFdD]?))" +
					             "[\\x00-\\x20]*");
					 
					 if (Pattern.matches(fpRegex,arg)){
				        //System.out.println(Double.valueOf(arg));
						 return true;
					 }
				    else {
				    	return false;
				        //System.out.println("wrong");
				    }
					 
				 }
				}