JavaSwing输入对话框，点击取消抛出异常的解决方法

 1                 double price = 0;
 2                 String textPrice = JOptionPane
 3                         .showInputDialog("请输入要调整的价格增(减)量");
 4 
 5                 if (textPrice == null) {
 6                     return;
 7                 }
 8                 else if(textPrice.equals("")){
 9                     JOptionPane.showMessageDialog(null, "请输入要调整的价格增(减)量","提示信息",JOptionPane.ERROR_MESSAGE);
10                     return ;
11                 }
12                 else{
13                     try {
14                         price = Double.parseDouble(textPrice);
15                         if (pid.changePrice(price)) {
16                             JOptionPane.showMessageDialog(null, "价格调整完成！");
17                         }
18                     } catch (Exception e1) {
19                         JOptionPane.showMessageDialog(null, "输入有误！");
20                     }
21 
22                 }
23             }