变量我正在学习Java，下面的程序只接受0的答案

Question

我有下面的代码来询问一个乘法问题，并询问用户答案，然后检查答案是否正确

我可以让它工作到检查答案的程度。它只接受0，这是因为出于某种原因，我将答案初始化为0

如果我在代码中将其更改为num1*num2，它将不会接受它。我在寻找帮助或资源来帮助我找到答案，我不只是想有人给我答案。提前谢谢

//Multiply.java -- prints multiplication questions for user to answer

import java.util.Random; // import Random
import java.util.Scanner; // import Scanner

public class Test 
{
    public static void main(String[] args) 
    {               
        @SuppressWarnings("resource")
        Scanner input = new Scanner( System.in );

        int guess; // the user's guess to the question

        createQuestion(); // display the first question to the user

        System.out.println( "Enter your answer (-1 to exit):" ); // asks the question
        guess = input.nextInt(); // accepts the users answer

        while ( guess != -1 ) // if guess is not -1
        { // start while
            checkResponse( guess ); // calls checkResponse to check guess

            System.out.println( "Enter your answer (-1 to exit):" ); // prompts user for answer
            guess = input.nextInt(); // the users answer that is entered
        } // end while  
    } // end main

    private static void createQuestion() 
    { // start createQuestion
        Random randomNumbers = new Random();

        // get two random numbers between 0 and 9
        int num1 = randomNumbers.nextInt( 10 );
        int num2 = randomNumbers.nextInt( 10 );

        @SuppressWarnings("unused")
        int answer = (num1 * num2); // answer to the question
        System.out.printf( "How much is %d times %d?\n", // prompts for the answer
                num1, num2 );
    } // end createQuestion

    private static void checkResponse(int guess) 
    { // start checkResponse
        int answer = 0; /* this is where I have the problem if I change 0 
         * to (num1 * num2) it can't resolve to a variable. I am trying to bring 
         * down the answer variable from createQuestion */

        if ( guess != answer ) // if the users answer is not correct
            System.out.println( "No. Please try again." );
        else
        { // start else
            System.out.println( "Very Good!" ); // if the users answer is correct
            createQuestion();
        } // end else
    } // end checkResponse
} // end class

Answer 1

在方法checkResponse之外声明“answer”，并将其作为测试类的成员。然后，从createQuestion方法中指定它的值

Answer 2

将guess和answer声明为Test的属性

public class Test 
{
     private static int guess;
     private static int answer;
     // ...
}

这样，你就可以在createQuestion()和^checkResponse()
两个功能都可以访问正确（和最新）值

Answer 3

您试图在其方法之外使用变量。您应该在方法之外声明变量