java正则判断小数

public static boolean isDecimal(String str){  return Pattern.compile("([1-9]+[0-9]*|0)(\\.[\\d]+)?").matcher(str).matches(); }  public static void main(String[] args){  System.out.println("123:"+isDecimal("123"));  System.out.println("0.123:"+isDecimal("0.123"));  System.out.println(".123:"+isDecimal(".123"));  System.out.println("1.23:"+isDecimal("1.23"));  System.out.println("123.:"+isDecimal("123."));  System.out.println("00.123:"+isDecimal("00.123"));  System.out.println("123.0:"+isDecimal("123.0"));  System.out.println("123.00:"+isDecimal("123.00"));  System.out.println("0123:"+isDecimal("0123")); }