JAVA 单独的类方法不增加我的主类方法中的变量

Question

这是我的基于文本的游戏的主要代码。

import java.util.Scanner;

public class D_M_RPG {
    public static void main(String[] args) {
        //Creating the class to call on my toolbox
        D_M_RPGtoolbox toolbox = new D_M_RPGtoolbox();

        //Creating the scanner class for user input
        Scanner input = new Scanner(System.in);

        //Initiating variables and final variables aswell as arrays
        //token variable to validate open spots in an array
        int slotCounter = 0;
        int inventoryExpander = 11;

        //First initiated will be the character creation variables
        String hairColor = "";
        String eyeColor = "";
        String skinColor = "";
        String gender = "";

        //Initiating the arrays for character inventory slots
        String[] weaponSlots = new String[10];

        //initiating the arrays for the character creation
        String[] hairColorARR = {"black","Green","Yellow","Brown","Blue","Blonde","Grey","White"};
        String[] eyeColorARR = {"Green","Brown","Blue","Grey",};
        String[] skinColorARR = {"White","brown","Black",};
        String[] genderARR = {"Male","Female"};

        //Creating the introduction title and introduction
        System.out.println("Welcome to, COLD OMEN.");
        System.out.println("\nNOVEMBER 12th, 2150: ONTARIO, CANADA");
        System.out.println("\nYou hear loud shouts and gun fire all around you but can't pinpoint the location of anything, you feel a bit dazed until someone grabs you and you open your eyes and snap out of it.");
        System.out.println("\nUnknown: 'Get up, its time to move out. Take this.'");
        System.out.println("\nUnknown hands you a 'M4-A4 RIFLE'");
        System.out.println("\nyou manage to catch a small glimpse of him before you get up.");

        //Character creation screen
        System.out.println();

        //ONLY WORKS ONCE WONT INCREMEMENT THE SLOTCOUNTER
        toolbox.insert(weaponSlots, slotCounter, inventoryExpander, "M4-A4 RIFLE");
        System.out.println("\n" + weaponSlots[0]);
        toolbox.insert(weaponSlots, slotCounter, inventoryExpander, "ak47");
        System.out.println(weaponSlots[0]);
    }
}

所以我用这个方法基本上将一个“项目”添加到 WeaponSlots 数组(库存)中，但每当我运行它时，它都会添加到数组 [0] 中的第一个元素，但它不会增加插槽计数器每次使用该方法时都应该增加一，这样我就不会替换数组中的任何项目它应该只添加项目直到其已满，这是使用 inventoryExpander 变量检查的。目前我让它打印数组中 0 和 0 处的元素，但我也检查了 1 ，并且 1 只是 null 没有添加任何项目，它仅替换 0 处的元素。这是递增方法的代码等:

public class D_M_RPGtoolbox {

    //method for random number generating to be used for crit hits, turns, loot generation etc
    public int randomGen(){
        int x = (int) (Math.random()*((20-0)+1)+0);
        return x;
    }

    //method for inserting into an array ONLY WORKS ONCE WONT INCREMEMENT THE SLOTCOUNTER FIX 
    public void insert(String[] a, int b, int d , String c) {
        if(b < d) {
            a[b] = c;
            b++;
        }//end of if statement
    }//end of method
}

Answer 1

您实际上在 b 中执行++ 操作的是 slotCounter 中值的副本。

变量slotCounter被“按值”传递到insert中。这与您可能想象的不同，它是“通过引用”传递的。

一种解决方案是从调用行执行 slotCounter++；另一种方法是让工具箱完全拥有 slotCounter 变量。

This question使用传递文档内容副本(按值)的图像，其中发送者不会看到对文档的更改；或者作为共享文档的链接(通过引用)，可以对发件人看到的同一页面进行更改。