java - 如果未输入有效整数，如何让程序因错误而终止？

Question

对于学校，我正在编写一个程序，用户输入三个整数，程序找到这三个整数的乘积并将结果输出给用户。老师要求我使用JOptionPane类。当输入无效整数时，如何使程序因错误而终止。另外，如何在 java 窗口中输出答案？提前致谢!

import javax.swing.JOptionPane;

public class ASTheProductofThreeGUI {

    public static void main(String[] args) {

        //initializes variable "answer" of type integer

        //prompts the user to enter their first integer for the product of three
        int value1 = Integer.parseInt(JOptionPane.showInputDialog("Enter your first"
                + " value as an integer")); 

        //prompts the user to enter their second integer
        int value2 = Integer.parseInt(JOptionPane.showInputDialog("Enter your second"
                + " value as an integer")); 

        //prompts the user to enter their third integer
        int value3 = Integer.parseInt(JOptionPane.showInputDialog("Enter your third"
                + " value as an integer")); 

        int answer = value1 * value2 * value3; 

Answer 1

如果字符串不是有效的 Integer，Integer.parseInt 将引发异常。您应该处理 NumberFormatException，然后调用 System.exit。

import javax.swing.JOptionPane;

public class ASTheProductofThreeGUI {

public static void main(String[] args) {

    //initializes variable "answer" of type integer

    //prompts the user to enter their first integer for the product of three
try {
    int value1 = Integer.parseInt(JOptionPane.showInputDialog("Enter your first"
            + " value as an integer")); 

    //prompts the user to enter their second integer
    int value2 = Integer.parseInt(JOptionPane.showInputDialog("Enter your second"
            + " value as an integer")); 

    //prompts the user to enter their third integer
    int value3 = Integer.parseInt(JOptionPane.showInputDialog("Enter your third"
            + " value as an integer")); 
 catch (NumberFormatException e){
    e.printStackTrace("Invalid Integer entered.");
    System.exit(0);
 }
    int answer = value1 * value2 * value3; 

另外，询问家庭作业是一个令人不悦的问题，所以我将把你的第二个问题留给你来找出答案。