java-线程“ main”中的异常java.lang.NumberFormatException：对于输入字符串：“”位于

Question

我试图运行以下示例，如果我在整数框/字段中输入字母或选择“确定/取消”而不输入值，则会退出确定或强制您输入有效的数字值。

对于文本字段，它可以正常工作，但不能用于整数，但出现以下错误。

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:592)
    at java.lang.Integer.parseInt(Integer.java:615)

 for this code,  is it possible to achieve what I want?  thanks for any answers in advance




import javax.swing.*;



   public class Methods
   {
    public static void main(String[] args)



    {  

        //THIS IS FOR THE 1ST POP UP BOX
        // prompt the user to enter their name
        String name = JOptionPane.showInputDialog( "What is your Firstname?");

        // get the user's input. note that if they press Cancel, 'name' will be 
        null
        System.out.printf("The user's name is '%s'.\n", name);

//

        //THIS IS FOR THE 2ND POP UP BOX
        // prompt the user to enter their name
        String nametwo = JOptionPane.showInputDialog(frametwo, "What is your 
       Surname?");

        // get the user's input. note that if they press Cancel, 'name' will be 
      null
        System.out.printf("The user's name is '%s'.\n", nametwo);

//

        //THIS IS FOR THE 3RD POP UP BOX
        // prompt the user to enter their age
        int namethree = Integer.parseInt(JOptionPane.showInputDialog(framethree, 
      "How old are you?"));
        //if (num.isEmpty())

        // get the user's input. note that if they press Cancel, 'age' will be 
       null
        System.out.printf("Your age is '%s'.\n", namethree);


        System.out.println("********************************");

        System.exit(0);
    }


    }

Answer 1

您需要在对Integer.parseInt的调用周围添加异常处理以捕获转换错误-此方法将为无法转换为Integer的任何字符串引发NumberFormatException。

就像是：

try
{
    int namethree = Integer.parseInt(JOptionPane.showInputDialog(framethree,
        "How old are you?"));
}
catch (NumberFormatException)
{
    //TODO: display an error message and retry the input
}