不能从静态上下文引用非静态变量量[重复]

Question

我最近开始用Java编码，我有一个关于轮盘赌/挖掘游戏（终端）的问题。

每次尝试使用“bank.amount”购买特定商品时，都会出现以下错误：

这是我的shop.java文件

package shop;
import coins.bank;
import java.util.Scanner;  // Import the Scanner class to write text for buying in the shop

public class shop {
    private static Object coins;

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        boolean playing;
        playing = true;

        System.out.println("\n");
        System.out.println("\t\t            •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••   ");
        System.out.println("\t\t           •••                                                                  •••   ");
        System.out.println("\t\t          •••                       Welcome to our shop!                         •••   ");
        System.out.println("\t\t           •••                                                                  •••   ");
        System.out.println("\t\t            •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••   ");

        Scanner shop = new Scanner(System.in);  // Create a Scanner object for shop
        System.out.println("\t\t               ⛏ 1. Buy BetterFarm - 3000 Coins (farm faster and more efficient!) ⛏");
        System.out.println("\t\t               \uD83D\uDCA8 2. Buy ShorterDelay - 2000 Coins (this way you don't have to wait so long!) \uD83D\uDCA8");
        System.out.println("\t\t               \uD83C\uDFB0 3. Buy Token for Casino - 1000 Coins \uD83C\uDFB0");
        System.out.println("\n");
        System.out.println("\t\t               \uD83D\uDCD9 Commands: \uD83D\uDCD9");
        System.out.println("\t\t               \uD83D\uDCD9 Betterfarm: /buy Betterfarm \uD83D\uDCD9");
        System.out.println("\t\t               \uD83D\uDCD9 ShorterDelay: /buy ShorterDelay \uD83D\uDCD9");
        System.out.println("\t\t               \uD83D\uDCD9 Token: /buy Token \uD83D\uDCD9");
        System.out.println("\n");

        while (playing) {
            String in = input.next();

            if (in.equals("/buy BetterFarm") && bank.amount >= 3000) {
                System.out.println("You've successfully bought BetterFarm!");
            }

            else {
                System.out.println("You don't have enough Coins to buy BetterFarm!");
            }
        }
    }
}

如果你需要更多的代码（例如，我的主类或银行类），请随时问我！

Answer 1

你需要一个银行的实例

Scanner input = new Scanner(System.in); 

Bank b = new Bank();
while (b.amount > 0) {
    String in = input.nextLine(); // your input contains spaces, use nextLine 
    if (in.equals("/buy BetterFarm") && b.amount >= 3000) {
        b.amount -= 3000;
        System.out.println("You've successfully bought BetterFarm!");
    } 
}