Question

我的大部分代码都是工作代码，就在我尝试添加用户输入的乘法时，我开始出错了。你能给我建议如何做得更好或摆脱错误吗？

package resittests;
import java.util.Scanner;
import javax.swing.JOptionPane;

public class Inputting {

    public static void main(String[] args) {
        Scanner Scan = new Scanner (System.in); // Creates the Scanner to allow input

        System.out.print("Enter a Number");
        String input = null;
        String first = Scan.next();
        int num1 = Integer.parseInt(input); 

        String Second; // Second Declared as a string
        Second = JOptionPane.showInputDialog("Enter Another Number");
        String input2 = null;
        int num2 = Integer.parseInt(input2);

        System.out.print("What is your Name?");
        String name = Scan.next();

        String Age; // Age Declared as a String 
        Age = JOptionPane.showInputDialog("Enter your age ");

        System.out.print( name + " "+ "(Aged" + " " + Age +  ")" + "," + "your answer is " + (num1 * num2) );
    }
}

Answer 1

线程中的异常＆＃34; main＆＃34; java.lang.NumberFormatException：java.lang.Integer.parseInt（Integer.java:542）中的null

如果Integer.parseInt无法将参数String解析为int，则抛出NumberFormatException - 堆栈跟踪指示它尝试解析的值，在本例中为{{ 1}}。原因是：您传递给null的字符串是Integer.parseInt。如果要解析用户输入，则将用户输入String传递给null，例如：

Integer.parseInt

请注意，如果用户未输入有效整数//String input = null; String first = Scan.next(); //int num1 = Integer.parseInt(input); int num1 = Integer.parseInt(first);，则会抛出Integer.parseInt

这是我的乘法错误还是我的整数？

1 个答案: