如何从另一个类访问变量？答案

【问题标题】：How can I access variable from another class?如何从另一个类访问变量？
【发布时间】：2015-02-28 10:43:46
【问题描述】：

我已经创建了我的类 Commands 的对象

Commands commands = new Commands();

但是，我需要访问该方法中的数组，不知道该怎么做。

Player.java

package com.PenguinGaming;

import java.util.Scanner;

public class Player {

public void User(){

    Commands commands = new Commands();

    int Maxlife = 25;
    int life = 25;
    int turns = 0;

    //Starting player location
    int playerX = 4;
    int playerY = 4;

    Scanner scanner = new Scanner(System.in);

    String input = null;


    while(life > 1){

        System.out.println("Player life: " + life + "/" + Maxlife);
        input = scanner.nextLine();
        input = input.toLowerCase();

        life -= 1;

        for(int i = 0; i == 30; i++){
            turns++;
            if(turns == 30){
                Maxlife += 5;
            }
        }

        if (input.equals(commands[0])) {
        // give description for player location
        System.out.println(locations[playerX][playerY]);
        }

        if(input.equals(commands[1])){
            //Go north
            System.out.println(locations[playerX][playerY+1]);
            playerY += 1;
        }

        if(input.equals(commands[2])){
            //Go east
            System.out.println(locations[playerX+1][playerY]);
            playerX += 1;
        }

        if(input.equals(commands[3])){
            //Go south
            System.out.println(locations[playerX][playerY-1]);
            playerY -= 1;
        }

        if(input.equals(commands[4])){
            //Go west
            System.out.println(locations[playerX-1][playerY]);
            playerX -= 1;
        }

        if(input.equals(commands[5])){
            break;
        }

        if(life <= 0){
            System.out.println("Looks like you have starved, better luck next game");
            break;
        }
        else
            System.out.println("You can not move in that direction");

    }
    System.exit(0);
}
}

Commands.java

package com.PenguinGaming;

public class Commands {

/*
 * Command list:
 * - investigate (advanced description)
 * - go north
 * - go south
 * - go west
 * - go east
 * - pick up
 * - eat
 * - drink from
 * - drink object
 * - climb up/down
 * - burn
 * - use object
 * - attack
 * - defend
 * - description (basic description)
 * - read
 * - life
 * - help (brings up command list)
 */

public void commandlist(){

    String[] commands = new String[6];
    commands[0] = "investigate";
    commands[1] = "go north";
    commands[2] = "go east";
    commands[3] = "go south";
    commands[4] = "go west";
    commands[5] = "terminate game";
}

}

【问题讨论】：

您想在commandlist() 中访问commands？将返回类型改为String[]，返回commands。
谢谢八月，问题似乎已经解决了。
您不希望您的命令永久存在于某个地方吗？每次有人需要命令列表时，您是否必须创建该 String[] ？它会改变吗？如果没有，则将其设为 private static final 并编写返回命令的 getter 方法。
还有一个约定，将包命名为全部小写。

标签： java arrays oop object

【解决方案1】：

Java 已经有了存储定义良好的常量值集的方法。它叫enum

public enum Commands {
    INVESTIGATE("investigate"),
    GO_NORTH("go north"),
    GO_EAST("go east"),
   ...

}

等等。

通过这种方式，您可以将 Commands 导入您编写的类，并通过返回 set 的 Commands.values() 获取其所有值，因此您可以随心所欲地对其进行迭代。这样，如果您发现需要添加另一个命令，您只需在一个地方执行此操作，因为您操作、检查这些值是否相等等。

我忘了提到这样做，您不必手动创建对象命令。

【讨论】：

【解决方案2】：

如果你想稍微清理一下你的代码，你可以这样做：

public String[] commandlist()
{
  return new String[]{"investigate", "go north", "go east", "go south", "go west", "terminate game"};
}

【讨论】：