[说明]
已知类Stock和类cxyjava都定义在cxyjava.java文件中，类Stock的定义中第14行前共有四行出现了错误，将下面代码修改正确并完善后的输出结果为：
0:0
1:23
请补齐第21行代码中的空缺。
[Java代码]
01 public class Stock{
02 static {
03 shares = 0;
04 share_val = 0.0;
05 }
06 public Stock () {getData (); }
07 public Stock(int n, int pr=0){
08 shares = n;
09 share_val = pr;
10 getData ();
11 }
12 public void getData() {
13 System. out .println (shares + " : " +share_val) ;
14 }
15 private int shares,
16 private int share_val;
17 };
18
19 public class cxyjava{
20 public static void main (String args [] } {
21 Stock a = (1) ;
22 Stock b = new Stock(1,23);
24 }
25 }