Java最大值和最小整数值错误消息输出

Question

我正在使用Java并试图在此代码中添加一条语句，该语句在:

之外显示错误消息

Exception in thread "main" java.util.InputMismatchException: For input string: 
"31243241234123423"
    at java.util.Scanner.nextInt(Scanner.java:2123)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at MaxInteger.main(MaxInteger.java:22)

Java提供的

错误消息。我想添加:

System.out.println("Your Integer value is out of range.");

这是我想要添加到的代码部分:

import java.util.Scanner;
public class Homework1a {
    public static void main(String[] args) {
        int intOne = 0;
        int intTwo = 0;
        String operation = " ";
        int result = 0;
        double divResult = 0.0;
        // Use the Scanner class to input data
        Scanner scannerIn = new Scanner(System.in);
        // Display of Program Introduction
        System.out.println("This program will take your integer inputs, " +
                            "along with the choosen operation and calculate the results");
        // Display for user to input the first integer
        System.out.println("Enter the first integer:");
            intOne = scannerIn.nextInt();
        // Display for user to input the second integer
        System.out.println("Enter the second integer:");
            intTwo = scannerIn.nextInt();
        // Display a list of instructions on the proper call for the operator
        System.out.println("");
        System.out.println("********** Operator Instructions **********");
        System.out.println("t For addition use +");
        System.out.println("t For subtraction use -"); 
        System.out.println("t For multiplication use *");  
        System.out.println("t For division use /");
        System.out.println("t For modulus use %");
        System.out.println("t For bitwise AND use &");
        System.out.println("t For bitwise inclusive OR use |");
        System.out.println("********************************************");
        System.out.println("");
        // Takes care of the ENTER key negating the String input below
        scannerIn.nextLine();
        // Display for user to input the chosen operator
        System.out.println("Enter the operation:");
            operation = scannerIn.nextLine();
    }
}

我试图合并的另一个实例是当加法，减法，乘法结果超过最大整数值时显示类似的提示。有什么建议或问题吗?

Answer 1

应该可以:

import java.util.InputMismatchException;
import java.util.Scanner;
public class Homework1a
{
    public static void main(String[] args)
    {
        int intOne = 0;
        int intTwo = 0;
        String operation = " ";
        int result = 0;
        double divResult = 0.0;
        // Use the Scanner class to input data
        Scanner scannerIn = new Scanner(System.in);
        // Display of Program Introduction
        System.out.println("This program will take your integer inputs, "
                + "along with the choosen operation and calculate the results");
        try
        {
            // Display for user to input the first integer
            System.out.println("Enter the first integer:");
            intOne = scannerIn.nextInt();
            // Display for user to input the second integer
            System.out.println("Enter the second integer:");
            intTwo = scannerIn.nextInt();
            // Display a list of instructions on the proper call for the operator
            System.out.println("");
            System.out.println("********** Operator Instructions **********");
            System.out.println("t For addition use +");
            System.out.println("t For subtraction use -");
            System.out.println("t For multiplication use *");
            System.out.println("t For division use /");
            System.out.println("t For modulus use %");
            System.out.println("t For bitwise AND use &");
            System.out.println("t For bitwise inclusive OR use |");
            System.out.println("********************************************");
            System.out.println("");
            // Takes care of the ENTER key negating the String input below
            scannerIn.nextLine();
            // Display for user to input the chosen operator
            System.out.println("Enter the operation:");
            operation = scannerIn.nextLine();
        }
        catch (InputMismatchException ex)
        {
            System.out.println("Your Integer value is out of range.");
        }
    }
}

Answer 2

有几种方法可以做到。

使用如果
使用try - catch

<标题>第一种方法

您可以使用if-语句检查输入是否大于Integer.MAX_VALUE。但是你需要使用更大容量的数据类型，否则当你输入的值大于Integer.MAX_VALUE(2147483647)时，它会抛出InputMismatchException。

Scanner scn = new Scanner(System.in);
Long num = 0L;
num = scn.nextLong();
if(num > Integer.MAX_VALUE)
    System.out.println("Your Integer value is out of range.");

---

<标题>第二种方法另一种方法是使用try-catch块。这样就不需要使用长数据类型来检查超过Integer.MAX_VALUE的输入。

Scanner scn = new Scanner(System.in);
int num = 0;
try{
    num = scn.nextInt();
}
catch(InputMismatchException e){
    System.out.println("Your Integer value is out of range.");  
} 

我个人更喜欢第二种方法，这就是try-catch块的意义所在-捕获意外行为，例如超出数据范围。此外，使用第二种方法，即使用户输入一个非常大的数字(例如99999999999999999999999999999999999999999)，程序也将打印"Your integer value is out of range"。第一种方法无法处理大于Long.MAX_VALUE的输入。

---

程序测试(第二种方法)

Input: 999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999
Your Integer value is out of range.