java - 如何在 Java 中的一个方法中使用另一个方法中的数组而不使其成为全局数组

Question

下面的代码询问用户他们的巴士路线以及一些相关信息。程序中反复出现错误。

我无法在第二种方法中使用该数组。我尝试将数组设为全局变量，但随后发生了错误。如何从 busRoutes() 访问数组变量decisionMaking()中的方法.

如果唯一的方法是将其设为全局变量，您能告诉我如何防止错误发生吗？

public class question {
    public static void main(String[] args) {
        busRoutes();
        decisionMaking();
        System.exit(0);
    }


    public static void busRoutes() {
        Scanner sc = new Scanner(System.in);

        System.out.println("How many bus routes are there");

        int routes = sc.nextInt();
        String[][] array = new String[routes][4];

        for (int i = 0; i < routes ; i++) {
            System.out.println("Please enter the bus route");
            System.out.println("What is the bus route");
            array[i][0] = sc.nextLine();
            System.out.println("Start Location");
            array[i][1] = sc.nextLine();
            System.out.println("End Location");
            array[i][2] = sc.nextLine();
            System.out.println("Who is the driver for bus route " + array[i][0]);
            array[i][3] = sc.nextLine();
        }
    }


    public static void decisionMaking() {
        System.out.println("Do you want to 1) Print all bus routes 2) Start a new day 3) Quit ? ");

        int decision = sc.nextInt();
        if (decision == 1) {
            for (int i = 0; i < array.length; i++) {
                System.out.println(Arrays.toString(array[i]));
            }
        }

        else if (decision == 3) {
            return;
        }
    }

    return;
}

} }

Answer 1

您的问题是 sc 和 array 对 decisionMaking 不可见，您可以将其设为全局变量或将其传递给该方法。

您不应该将所有内容设为全局，但如果未修改，则将其作为参数传递。

public static void main(String[] args) {
    busRoutes();
    System.exit(0);
}

从主方法中删除了decisionMaking。并向其中添加了 2 个参数。

public static void DecisionMaking(Scanner sc, String[][] array)

现在我们从busRoutes传递它

public static void busRoutes() {
    Scanner sc = new Scanner(System.in);
    System.out.println("How many bus routes are there");
    int routes = sc.nextInt();
    String[][] array = new String[routes][4];
    for (int i = 0; i < routes; i++) {
        System.out.println("Please enter the bus route");
        System.out.println("What is the bus route");
        array[i][0] = sc.nextLine();
        System.out.println("Start Location");
        array[i][1] = sc.nextLine();
        System.out.println("End Location");
        array[i][2] = sc.nextLine();
        System.out.println("Who is the driver for bus route " + array[i][0]);
        array[i][3] = sc.nextLine();
    }
    decisionMaking(sc, array);
}

这是完整的代码。

import java.util.Arrays;
import java.util.Scanner;

public class question {
    public static void main(String[] args) {
        busRoutes();
        System.exit(0);
    }


    public static void busRoutes() {
        Scanner sc = new Scanner(System.in);
        System.out.println("How many bus routes are there");
        int routes = sc.nextInt();
        String[][] array = new String[routes][4];
        for (int i = 0; i < routes; i++) {
            System.out.println("Please enter the bus route");
            System.out.println("What is the bus route");
            array[i][0] = sc.nextLine();
            System.out.println("Start Location");
            array[i][1] = sc.nextLine();
            System.out.println("End Location");
            array[i][2] = sc.nextLine();
            System.out.println("Who is the driver for bus route " + array[i][0]);
            array[i][3] = sc.nextLine();
        }
        decisionMaking(sc, array);
    }


    public static void decisionMaking(Scanner sc, String[][] array) {
        System.out.println("Do you want to 1) Print all bus routes 2) Start a new day 3) Quit ? ");
        int decision = sc.nextInt();
        if (decision == 1) {
            for (int i = 0; i < array.length; i++) {
                System.out.println(Arrays.toString(array[i]));

            }
        } else if (decision == 3) {

        }
    }
}