问题

这是我的代码：

using UnityEngine;

public class movement : MonoBehaviour
{
    public Rigidbody rb;
    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void FixedUpdate()
    {
        rb.AddForce(0, 0, 2000 * Time.deltaTime);

    }
}

这是错误信息：

ArgumentNullException: 值不能为空。
参数名称：_unity_self
UnityEditor.SerializedObject.FindProperty (System.String propertyPath) (at <582c35e8f45345d395e99f8e72e3c16d>:0)
UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.BindPropertyRelative (UnityEngine.UIElements.IBindable field, UnityEditor.SerializedProperty parentProperty) (at :0)
UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.BindTree (UnityEngine.UIElements.VisualElement element, UnityEditor.SerializedProperty parentProperty) (at :0)
UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.ContinueBinding (UnityEngine.UIElements.VisualElement element, UnityEditor.SerializedProperty parentProperty) (at :0)
UnityEditor.UIElements.Bindings.DefaultSerializedObjectBindingImplementation+BindingRequest.Bind (UnityEngine.UIElements.VisualElement element) (at :0)
UnityEngine.UIElements.VisualTreeBindingsUpdater.Update () (at :0)
UnityEngine.UIElements.VisualTreeUpdater.UpdateVisualTreePhase (UnityEngine.UIElements.VisualTreeUpdatePhase phase) (at :0)
UnityEngine.UIElements.Panel.UpdateBindings () (at :0)
UnityEngine.UIElements.UIElementsUtility.UnityEngine.UIElements.IUIElementsUtility.UpdateSchedulers () (at :0)
UnityEngine.UIElements.UIEventRegistration.UpdateSchedulers () (at :0)
UnityEditor.RetainedMode.UpdateSchedulers () (at :0)

<details>
<summary>英文:</summary>

This is my code:

using UnityEngine;

public class movement : MonoBehaviour
{
public Rigidbody rb;
// Start is called before the first frame update
void Start()
{

}

// Update is called once per frame
void FixedUpdate()
{
    rb.AddForce(0,0,2000 * Time.deltaTime);

}

}

This the error:

    ArgumentNullException: Value cannot be null.
    Parameter name: _unity_self
    UnityEditor.SerializedObject.FindProperty (System.String propertyPath) (at <582c35e8f45345d395e99f8e72e3c16d>:0)
    UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.BindPropertyRelative (UnityEngine.UIElements.IBindable field, UnityEditor.SerializedProperty parentProperty) (at <af95451922f042e9a8d1a10956fb36a2>:0)
    UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.BindTree (UnityEngine.UIElements.VisualElement element, UnityEditor.SerializedProperty parentProperty) (at <af95451922f042e9a8d1a10956fb36a2>:0)
    UnityEditor.UIElements.Bindings.SerializedObjectBindingContext.ContinueBinding (UnityEngine.UIElements.VisualElement element, UnityEditor.SerializedProperty parentProperty) (at <af95451922f042e9a8d1a10956fb36a2>:0)
    UnityEditor.UIElements.Bindings.DefaultSerializedObjectBindingImplementation+BindingRequest.Bind (UnityEngine.UIElements.VisualElement element) (at <af95451922f042e9a8d1a10956fb36a2>:0)
    UnityEngine.UIElements.VisualTreeBindingsUpdater.Update () (at <d293f45b4ec64e6c9e762fe89794e7a5>:0)
    UnityEngine.UIElements.VisualTreeUpdater.UpdateVisualTreePhase (UnityEngine.UIElements.VisualTreeUpdatePhase phase) (at <d293f45b4ec64e6c9e762fe89794e7a5>:0)
    UnityEngine.UIElements.Panel.UpdateBindings () (at <d293f45b4ec64e6c9e762fe89794e7a5>:0)
    UnityEngine.UIElements.UIElementsUtility.UnityEngine.UIElements.IUIElementsUtility.UpdateSchedulers () (at <d293f45b4ec64e6c9e762fe89794e7a5>:0)
    UnityEngine.UIElements.UIEventRegistration.UpdateSchedulers () (at <d293f45b4ec64e6c9e762fe89794e7a5>:0)
    UnityEditor.RetainedMode.UpdateSchedulers () (at <af95451922f042e9a8d1a10956fb36a2>:0)






</details>


# 答案1
**得分**: 3

`rb` 在你的代码中没有被赋值，也没有在Unity检视面板中设置。

```csharp
public class movement : MonoBehaviour
{
    public Rigidbody rb;
    // Start is called before the first frame update
    void Start()
    {
       rb = gameObject.GetComponent<Rigidbody>();
    }

    // 你的代码...
}

public class movement : MonoBehaviour
{
    public Rigidbody rb;
    // Start is called before the first frame update
    void Start()
    {
       rb = gameObject.GetComponent<Rigidbody>();
    }

    //your code....
}