无法正确使用Unity中其他脚本中的变量

如何解决无法正确使用Unity中其他脚本中的变量

我有以下问题，所以我不能使用其他脚本的可变形式。在我的游戏中，有一个困难的选择屏幕，当用户选择它的级别时，应该给变量适当的值。脚本如下：

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));
    
}

我仍然遇到有关Null引用的错误，所以我认为获取适当的值有问题。我究竟做错了什么？请帮助我。

解决方法

我已经复制了这两个类，并且一切正常，所以这个问题是由另一个变量引起的， 或者，

这两个类在同一个游戏对象中吗？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...

看看异常在哪里指吗？

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

编辑：

如评论所示， 问题是两个场景在不同的场景上，因此GameObject.Find和public GameObject将给出null

要解决此问题，请使用PlayerPrefs

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

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

并删除“ d”

,

我尝试过您的代码看起来可以正常工作。

假设游戏运行正常，并且在播放时获得“空引用”。

您通过检查是否

来签入代码

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));

}

还尝试添加 Debug.Log（）来检查返回的值。

其他查询，用于为同一场景传递不同的值

假设您要基于难度级别加载相同的场景，而只是想获得不同的 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");
}
}

一旦我们具有从场景中返回值的功能，接下来我们将对Ball2脚本进行更改

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),maxYspeed) * (Random.value > 0.5f ? -1 : 1));
    
}