java - 局部变量 user_input 从内部类内部访问；需要宣布最终

Question

import java.util.Scanner;

public class Testing {

    public static void main(String [] args)  {

        Scanner user_input = new Scanner( System.in );

        String start;
        System.out.print("(Don't put capital letters) ");

        String color;
        System.out.print("Enter Your Favorite Color: ");
        color = user_input.next ( );

        String animal;
        System.out.print("Enter Your Favorite Animal: ");
        animal = user_input.next ( );

        String preference;
        preference = color + " and that your favorite animal is a " + animal;

        System.out.println("From the information I gathered, I figured out that you like the color " + preference);

        class A {
            public void Main(String[] args) {
                Scanner input = new Scanner(System.in);
                    System.out.println("Do you want to hear a joke?");
                String a = user_input.next ( );

                if (a.equalsIgnoreCase("yes")) ;
                    System.out.println("What did the fish say when he ran into a wall? Dam");

                if(a.equalsIgnoreCase("no")) ;
                    System.out.println("Oh..."); }

        }
    }
}

这就是错误

Testing.java:29: error: local variable user_input is accessed from within inner class; needs to be declared final
    String a = user_input.next ( );
               ^

1 个错误

我刚刚弄乱了代码，错误不断增加，所以我决定询问比我更有经验的人。我只使用了一天java，这是我创建的第一个程序，我已经搜索了至少2个小时的解决方案，但找不到，所以我决定询问。我之前编译过它，但它没有“user_input.next”，所以它的行为就像“class A”下面的整行代码都是不可见的，它不允许我输入任何内容，使其毫无用处。我然后输入 user_input 以便我可以输入一些内容，但是出现了大量错误，但这是不断弹出的一个错误。

Answer 1

该错误很可能是由于您声明扫描仪 (input)，然后使用其他类中的扫描仪 (user_input)

试试这个代码

import java.util.Scanner;

public class Testing 
{
    public void input1()
    {
        Scanner user_input = new Scanner( System.in );

        System.out.print("(Don't put capital letters) ");

        String color;
        System.out.print("Enter Your Favorite Color: ");
        color = user_input.next();

        String animal;
        System.out.print("Enter Your Favorite Animal: ");
        animal = user_input.next();

        String preference;
        preference = color + " and that your favorite animal is a " + animal;

        System.out.println("From the information I gathered, I figured out that you like the color " + preference);
    }

    public void input2()
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Do you want to hear a joke?");
        String a = input.next();

        if(a.equalsIgnoreCase("yes"))
        {
            System.out.println("What did the fish say when he ran into a wall? Dam");
        }
        else if(a.equalsIgnoreCase("no"))
        {
            System.out.println("Oh...");
        }
    }

    public static void main(String[] args)
    {
        Testing tS = new Testing();
        tS.input1();
        tS.input2();
    }
}

这段代码中有两个方法； 输入1和输入2。这些方法包含您尝试与命令控制台进行的两个对话。然后在 main 方法中初始化该类并运行这两个方法。