JAVA类中方法能调用类本身实例么？

假设人Person一个对象，有一个面包Magicbread对象,
public class Magicbread {
public void magic(Person p){
p.setHeight(p.getHeight()+1);
}
}
public class Person {
private float height;
public void eatBread(Magicroom room,int n){
for(int i=0;i<n;i++){
room.getBread().magic(this);
}
}
}
public class Magicroom {
private Magicbread bread;
public Magicroom(){
}
public Magicbread getBread(){
return bread;
}
}
报错后我分析后面这个magic参数应该是Person的一个实例，用this应该有问题。这种情况应该怎么解决啊？

height缺少get/set方法

public class Person {
    private float height;

    public float getHeight() {
        return height;
    }

    public void setHeight(float height) {
        this.height = height;
    }

    public void eatBread(Magicroom room, int n){
        for(int i=0;i<n;i++){
            room.getBread().magic(this);
        }
    }
}

Magicroom 类中bread没有实例化，导致空指针

class Magicroom {
    private Magicbread bread;
    public Magicroom(){
        bread=new Magicbread();
    }
    public Magicbread getBread(){
        return bread;
    }
}

public class Magicbread {
public void magic(float height,Person p){
p.setHeight(p.getHeight()+1);
}
}
public class Person {
private float height;
public void eatBread(Magicroom room,int n){
for(int i=0;i<n;i++){
room.magic(n,this);
}
}
}

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