Java에서 문자열이 숫자인지 확인

    public class CheckStrIsNum {   
        public static void main(String[] args) {     
            double aa = -192322.1212;    
            String a = "-192322.1212";  
            String b = "-192322a1212";     
            String c = "Java";  
            String d = "5";    
            /** 判断是否全为数字 */                     
            System.out.println(checkStrIsNum01(Double.toString(aa)));        
            System.out.println(checkStrIsNum01(a));        
            System.out.println(checkStrIsNum01(b));        
            System.out.println(checkStrIsNum01(c));        
            System.out.println(checkStrIsNum01(d)); 
        }
        
        /**
         * 利用Java的character.isDigit方法进行处理
         */
        public static boolean checkStrIsNum01(String str) {    
            for (int i = 0; i < str.length(); i++) {    
                System.out.println(str.charAt(i)); 
                if (!Character.isDigit(str.charAt(i))) { 
                    return false;  
                }
            } 
            return true;
       }
    }

    public class CheckStrIsNum {   
        public static void main(String[] args) {     
            double aa = -192322.1212;    
            String a = "-192322.1212";  
            String b = "-192322a1212";     
            String c = "Java";  
            String d = "5";    
            /** 判断是否全为数字 */                     
            System.out.println(checkStrIsNum02(Double.toString(aa)));        
            System.out.println(checkStrIsNum02(a));        
            System.out.println(checkStrIsNum02(b));        
            System.out.println(checkStrIsNum02(c));        
            System.out.println(checkStrIsNum02(d)); 
        }
        
        private static Pattern NUMBER_PATTERN = Pattern.compile("-?[0-9]+(\\.[0-9]+)?");
        /** 
         * 利用正则表达式来判断字符串是否为数字 
         */
         public static boolean checkStrIsNum02(String str) { 
            String bigStr; 
            try {      
                /** 先将str转成BigDecimal，然后在转成String */
                bigStr = new BigDecimal(str).toString(); 
            } catch (Exception e) { 
                /** 如果转换数字失败，说明该str并非全部为数字 */
                return false; 
            } 
            Matcher isNum = NUMBER_PATTERN.matcher(str); 
            if (!isNum.matches()) {    
                return false; 
            }  
            return true;
        }
    }