Unity study notes on the problem of NullReferenceException when initializing and assigning arrays of custom classes

question

As shown in the figure below, when the array element of the custom class is assigned, an error "NullReferenceException: Object reference not set to an instance of an object" is reported.

在这里插入代码片

solution

This is because the array must be instantiated before it can be assigned a value after it is initialized.
The correct code is:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class CustomClass
{
    
    
    public string name;
    public GameObject gameObject;
}

public class CustomClassArray : MonoBehaviour
{
    
    
    //父物体
    public GameObject parent;
    //存储自定义类的数组
    [SerializeField]public CustomClass[] myArray;
    
    // Start is called before the first frame update
    void Start()
    {
    
    
        //初始化数组
        myArray = new CustomClass[parent.transform.childCount];

        //将子物体全部赋值到数组里
        for(int i = 0; i < parent.transform.childCount; i++)
        {
    
    
            //【关键点】每个元素要先实例化
            myArray[i] = new CustomClass();

            //才能赋值
            myArray[i].gameObject = parent.transform.GetChild(i).gameObject;
            myArray[i].name = parent.transform.GetChild(i).gameObject.name.ToString();
        }
    }   
}