从另一个类调用变量

Question

我正在做一个新的项目，我试图建立一个货币系统，在那里我可以提取它，以转移到另一个变量（在另一个类）。我在解决这个问题上遇到了一些问题，我对如何编写代码感到非常失望。下面是我想链接的类（我想让“coinsamount”在我做/存款时进入类2“amount”

package Main;
import coins.bank;
import java.util.Random;
import java.util.Scanner;
public class Main {

    public void coinmanagement() {
        ///call class here 

    }



    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int coinsamount = 0;
        boolean mining;
        boolean playing;
        mining = false;
        playing = true;
        Random coins = new Random();
        System.out.println("Bot successfully started");






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


            if (in.equals("/coins"))
                System.out.println("You have " + coinsamount + " coins!");

            if (in.equals("/mine")) {
                int minedcoins = coins.nextInt(200) + 1;
                coinsamount += minedcoins;
                System.out.println("You've mined " + minedcoins + " coins!");
            }

            if (in.equals("/deposit"))

                System.out.println("You sucessfully deposited" +    +  "coins");

            if (in.equals("/stop")) {
                break; }

            if (in.equals("/shop"))
                shop s = new shop();
            }
        }
    }

第2类：

package coins;
import Main.Main;
public class bank {
    private int amount = 0;

    public void add(int amount) {
        this.amount += amount;
    }
}

Answer 1

如果我没听错你进去的时候

if (in.equals("/deposit"))

你想把钱存入银行。

要做到这一点，您应该按照以下方式编写代码

package Main;
import coins.bank;
import java.util.Random;
import java.util.Scanner;
public class Main {

    public void coinmanagement() {
        ///call class here 

    }



    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int coinsamount = 0;
        boolean mining;
        boolean playing;
        mining = false;
        playing = true;
        Random coins = new Random();
        System.out.println("Bot successfully started");
        Bank bank = new Bank();






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


            if (in.equals("/coins"))
                System.out.println("You have " + coinsamount + " coins!");

            if (in.equals("/mine")) {
                int minedcoins = coins.nextInt(200) + 1;
                coinsamount += minedcoins;
                System.out.println("You've mined " + minedcoins + " coins!");
            }

            if (in.equals("/deposit"))
                bank.add(coinsamount);

                System.out.println("You sucessfully deposited" +    +  "coins");

            if (in.equals("/stop")) {
                break; }

            if (in.equals("/shop"))
                shop s = new shop();
            }
        }
    }

package coins;
import Main.Main;
public class bank {
    private int amount = 0;

    public Bank() {
    }

    public void add(int amount) {
        this.amount += amount;
    }
}

我在这里所做的是在main类中实例化Bank对象，就像在if语句中实例化Shop对象一样。如果您想要访问对象中的成员或方法/函数，则需要在要使用它们的类中实例化它们。

我在主类中作用域的顶层这样做的原因是为了在主类中的任何地方都可以访问它。您可以在https://www.baeldung.com/java-variable-scope中了解作用域。

因为它在作用域内是可访问的，所以我可以在任何地方调用它，并调用bank.add（）方法。