无法在 Unity 中正确使用来自其他脚本的变量

Question

我有以下问题，所以我不能使用其他脚本的变量形式。在我的游戏中有难度 select 屏幕，当用户选择它的级别时，它应该给变量适当的值。脚本如下所示：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;

public class DifManager : MonoBehaviour
{
public float dif;

public void easy()
{
    dif = 1.05f;
    SceneManager.LoadScene("matchlenght");
}

public void normal()
{
    dif = 1.15f;
    SceneManager.LoadScene("matchlenght");
}

public void hard()
{
    dif = 1.4f;
    SceneManager.LoadScene("matchlenght");
}
}

在游戏场景的另一个脚本中，我想使用 dif 变量来设置 DifficultyMultiplier，它看起来像这样：

using UnityEngine;

public class Ball2 : MonoBehaviour
{

private matchlength mlength;
public float difficultMultiplier;
public float minXspeed = 0.8f;
public float maxXspeed = 1.2f;

public float minYspeed = 0.8f;
public float maxYspeed = 1.2f;
public DifManager d;
private Rigidbody2D ballRigidbody;
private GameObject secondPaddle;

// Start is called before the first frame update
void Start()
{
    d = gameObject.GetComponent<DifManager>();
    secondPaddle = GameObject.Find("Paddle2");
    difficultMultiplier = d.dif;
    mlength = gameObject.GetComponent<matchlength>();
    ballRigidbody = GetComponent<Rigidbody2D>();
    ballRigidbody.velocity = new Vector2(Random.Range(minXspeed, maxXspeed) * (Random.value > 0.5f ? 
     -1 : 1), Random.Range(minYspeed, maxYspeed) * (Random.value > 0.5f ? -1 : 1));
    
}

我仍然收到关于 Null 引用的错误，所以我想获取正确的值是有问题的。我究竟做错了什么？请帮助我。

Answer 1

我已经复制了这两个类并且一切正常，所以问题是由另一个变量引起的，或者，

这两个类是同一个游戏对象吗？这是我发现导致此异常的唯一方法...... 如果是这样，

使用此行获取“DifManager”

d =  GameObject.Find("yourGameObject").GetComponent<DifManager>();

或

Public GameObject s // the game object have "DifManager" class

 d = s.GetComponent<DifManager>();

如果没有，

尝试调试您的代码...

看看异常指的是哪里？

喜欢Ball2.Start () (at Assets/Scripts/Ball2.cs:23)

编辑：

如评论所示，问题是不同场景下的 2 类，所以 GameObject.Find 和 public GameObject 会给出 null

解决这个问题，使用PlayerPrefs

而不是 dif = 1.05f 添加 PlayerPrefs.SetFloat("dif", 1.05f); 对于所有 dif 个州

而不是 difficultMultiplier = d.dif; 添加 difficultMultiplier = PlayerPrefs.GetFloat("dif");

并删除“d”

Answer 2

我试过你的代码看起来工作正常。

假设游戏运行良好，并且您在玩游戏时得到的是 Null Reference。

您通过检查

d = gameObject.GetComponent();

是否被引用。

void Start()
{
 d = gameObject.GetComponent<DifManager>();
 secondPaddle = GameObject.Find("Paddle2");

   if (d!= null)// Checks if the object exist, based on this you can try debugging.
   // you can add the same for SecondPaddle and mlength and check if its not equals to null....
  {

    difficultMultiplier = d.dif; 

  }

mlength = gameObject.GetComponent<matchlength>();
ballRigidbody = GetComponent<Rigidbody2D>();
ballRigidbody.velocity = new Vector2(Random.Range(minXspeed, maxXspeed) * (Random.value > 0.5f ? 
 -1 : 1), Random.Range(minYspeed, maxYspeed) * (Random.value > 0.5f ? -1 : 1));

}

也可以尝试添加 Debug.Log() 来检查正在 returned 的值。

为同一场景传递不同值的附加查询

假设您想要根据难度级别加载相同的场景，并且只想获得不同的 dif 值。

请找到以下所需的代码更改。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;

public class DifManager : MonoBehaviour
{

public static float dif=0.0f; // change value as static

public static float GetdiffVariable() { return dif; }//We will take this function to return us the "dif" value based upon the Scene in our case its easy,normal or hard

public void easy()
{
    dif = 1.05f;
    SceneManager.LoadScene("matchlenght");
}

public void normal()
{
    dif = 1.15f;
    SceneManager.LoadScene("matchlenght");
}

public void hard()
{
    dif = 1.4f;
    SceneManager.LoadScene("matchlenght");
}
}

一旦我们有了 return 我们场景中的值的功能，接下来我们将更改 Ball2 脚本

using UnityEngine;

public class Ball2 : MonoBehaviour
{

private matchlength mlength;
public float difficultMultiplier;
public float minXspeed = 0.8f;
public float maxXspeed = 1.2f;

public float minYspeed = 0.8f;
public float maxYspeed = 1.2f;
public DifManager d;
private Rigidbody2D ballRigidbody;
private GameObject secondPaddle;

// Start is called before the first frame update
void Start()
{
    //d = gameObject.GetComponent<DifManager>(); we dont need this line anymore we can directly assign as we are only concerned with the return value for our Scene Difficulty

   
    difficultMultiplier = d.GetdiffVariable();//Should return you different values based on the easy, normal or hard.

    Debug.Log("difficultMultiplier");// cross verify in console
    secondPaddle = GameObject.Find("Paddle2");

    mlength = gameObject.GetComponent<matchlength>();
    ballRigidbody = GetComponent<Rigidbody2D>();
    ballRigidbody.velocity = new Vector2(Random.Range(minXspeed, maxXspeed) * (Random.value > 0.5f ? 
     -1 : 1), Random.Range(minYspeed, maxYspeed) * (Random.value > 0.5f ? -1 : 1));
    
}

无法在 Unity 中正确使用来自其他脚本的变量

Can't properly use variable from other script in Unity

variables

scripting