Java中与字符串相关的问题：为什么我的级别提升/降级没有正确更新？

我试图用Java编写此程序。

我可以从构造函数中读取字符串，并使用定界符将字符串分开。但是，每次尝试调用诸如promote()这些值之类的方法时，该值都保持不变。布尔方法promote()显示true，但级别不会增加。

例如：如果构造函数的字符串是："Harry#wizard#broom"，则：

name <- "Harry"
level <- "wizard"
supplies <- "broom"

name，level以及broom所有私有数据实例（我不知道是否应该使用数据实例或局部变量）。

但是，每当我调用harry.promote()它返回true但级别保持不变时，它都不会升级。中的初始值level似乎会覆盖它。

我写了下面的代码：

import java.util.Scanner;
import java.io.*;

public class Magician
{
    private String name;
    private String level;
    private String supplies;
    private double health;
    private int galleons;

    public Magician(String phrase) //phrase will be sth like this: Harry#wizard#broom#staff
    {

        health = 4000;
        galleons = 200;
        Scanner firstScan = new Scanner(details);
        firstScan.useDelimiter("#");
        name = firstScan.next();
        level = firstScan.next();
        if (firstScan.hasNext())
        {
            supplies = firstScan.next(); 
            while (firstScan.hasNext())
            {        
                supplies = supplies + " " + firstScan.next();
            }
        }
        else 
        {
            supplies ="";
        } 

    }
    public String getName()
    {
        return name;
    }
    public String getLevel()
    {
        return level;
    }
    public int getGalleons()
    {
        return galleons;
    }
    public double getHealth()
    {
        return health;
    }
    public String getSupplies()
    {
        return supplies;
    }
    //Mutators 
    public void setName(String nameUpdate)
    {
        name = nameUpdate;
    }
    public void setLevel(String levelUpdate)
    {
        level =levelUpdate;
    }
    public void setGalleons(int galleonsUpdate)
    {
        galleons = galleonsUpdate;
    }
    public void setHealth(double healthUpdate)
    {
        health = healthUpdate;
    }
    public void setSupplies(String suppliesUpdate)
    {
        supplies = suppliesUpdate;
    }
    // boolean promote, promotes a level up
    public boolean promote()
    {
        if (level == "apprentice")
        {
            level = "wizard";
            galleons +=100;
            return true;
        }
        else if (level == "wizard")
        {
            level = "mage";
            galleons +=100;
            return true;
        }
        else if (level == "mage")
        {
            level = "sorcerer";
            galleons +=100;
            return true;
        }
        else if (level == "sorcerer")
        {
            level = "shaman";
            galleons +=100;
            return true;
        }
        else if (level == "shaman")
        {
            return false;
        }
        return true;
    }
    public boolean downgradeLevel()
    {
        if (level == "shaman")
        {
            level = "sorcerer";
            return true;
        }
        else if (level == "sorcerer")
        {
            level = "mage";
            return true;
        }
        else if (level == "mage")
        {
            level = "wizard";
            return true;
        }
        else if (level == "wizard")
        {
            level = "apprentice";
            return true;
        }
        else if (level == "apprentice")
        {
            return false;
        }
        if(galleons>= 100)
        {
            galleons -=100;
        }
        else
        {
            galleons =0;
        }
        return true;
    }