如何在Person类方法中访问Robot类对象属性？遇找不到r1变量错误

错误原因 #

r1是Main类中main方法的局部变量，作用域仅限main方法内部。Person类的isOwnedby()方法属于独立类的成员方法，无法直接访问外部方法的局部变量，因此编译报错。

你的代码中Person类已经定义了robotOwned成员变量，用来存储人物关联的机器人对象，这才是获取对应机器人名字的正确途径。

修复方案 #

修改Person类的isOwnedby()方法，通过robotOwned成员变量访问关联机器人的名字，同时注意字符串拼接时的空格，避免输出内容连在一起：

void isOwnedby() {
    // 直接访问机器人的rname属性，或调用你定义的rname()方法均可
    System.out.println(robotOwned.rname + " is owned by " + this.name);
}

完整修复代码 #

public class Main
{
    public static void main(String[] args) {
        //Robot类对象
        Robot r1 = new Robot("Jerry", "Red", 30);
        r1.introduceself();
        Robot r2 = new Robot("Tom", "Blue", 40);
        r2.introduceself();
        
        //Person类对象
        Person p1 = new Person("Alice", "Aggresive", false);
        Person p2 = new Person("Becky", "Talkative", true);
        p1.robotOwned = r2;
        p2.robotOwned = r1;
        
        p1.robotOwned.introduceself(); //等同于r2.introduceself()
        p2.robotOwned.introduceself(); //等同于r1.introduceself()
        p1.isOwnedby();
        p2.isOwnedby(); // 可添加此行测试p2的关联结果
    }
}

class Robot 
{
    String rname;
    String color;
    int weight;
    
    //构造方法
    Robot (String n, String c, int w)
    {
        this.rname = n;
        this.color = c;
        this.weight = w;
    }
    
    void introduceself()
    {
        System.out.println("My name is " + this.rname);
    }
    
    public String rname()
    {
        return rname;
    }
}

class Person
{
    String name;
    String personality;
    boolean isSitting;
    Robot robotOwned;
    
    //构造方法
    Person (String n, String p, boolean i)
    {
        this.name = n;
        this.personality = p;
        this.isSitting = i;
    }
    
    //成员方法
    void isOwnedby()
    {
        System.out.println(robotOwned.rname + " is owned by " + this.name);
    }
      
    public String pname()
    {
        return name;
    }
}

运行结果 #

执行代码后会输出：

My name is Jerry
My name is Tom
My name is Tom
My name is Jerry
Tom is owned by Alice
Jerry is owned by Becky

内容的提问来源于stack exchange，提问作者Nikhil Koshti