Référence d'objet non définie sur une instance d'un objet Didacticiel C# Unity

Question

Je travaille sur la création d'un jeu à l'aide du didacticiel 2D de type rouge fourni par unity. Tout fonctionne comme prévu, loin du mouvement. Lorsque le jeu s'exécute, un error apparaît.

"NullReferenceException: (at actif/complété/scripts/Player.cs: 39) référence d'objet non définie à une instance d'un objet completed.player.start()"

Ceci est la ligne de Code provoquant l'erreur: healthText.text = "Health: " + health;

le code pour le script entier est ci-dessous:

using UnityEngine; 
using System.Collections; 
using UnityEngine.SceneManagement; 
using UnityEngine.UI; //Allows us to use UI. 

namespace Completed 
    { 
    //Player inherits from MovingObject, our base class for objects that can move, Enemy also inherits from this. 
    public class Player : MovingObject 
    { 
     public float restartLevelDelay = 1f;  //Delay time in seconds to restart level. 
     public int pointsPerGoodFood = 10;   //Number of points to add to player health points when picking up a GoodFood object. 
     public int pointsPerOkayFood = 20;   //Number of points to add to player health points when picking up a OkayFood object. 
     public int wallDamage = 1;     //How much damage a player does to a wall when attacking it. 
     public Text healthText;      //UI Text to display current player health total. 
     public AudioClip moveSound1;    //1 of 2 Audio clips to play when player moves. 
     public AudioClip moveSound2;    //2 of 2 Audio clips to play when player moves. 
     public AudioClip eatSound1;     //1 of 4 Audio clips to play when player collects a GoodFood object. 
     public AudioClip eatSound2;     //2 of 4 Audio clips to play when player collects a GoodFood object. 
     public AudioClip eatSound3;     //3 of 4 Audio clips to play when player collects a OkayFood object. 
     public AudioClip eatSound4;     //4 of 4 Audio clips to play when player collects a OkayFood object. 
     public AudioClip gameOverSound;    //Audio clip to play when player dies. 

     private Animator animator;     //Used to store a reference to the Player's animator component. 
     private int health;       //Used to store player health points total during level. 

     //Start overrides the Start function of MovingObject 
     protected override void Start() 
     { 
      //Get a component reference to the Player's animator component 
      animator = GetComponent<Animator>(); 

      //Get the current health point total stored in GameManager.instance between levels. 
      health = GameManager.instance.playerHealthPoints; 

      //Set the foodText to reflect the current player health total. 
      healthText.text = "Health: " + health; 

      //Call the Start function of the MovingObject base class. 
      base.Start(); 
     } 


     //This function is called when the behaviour becomes disabled or inactive. 
     private void OnDisable() 
     { 
      //When Player object is disabled, store the current local health total in the GameManager so it can be re-loaded in next level. 
      GameManager.instance.playerHealthPoints = health; 
     } 


     private void Update() 
     { 
      //If it's not the player's turn, exit the function. 
      if(!GameManager.instance.playersTurn) return; 

      int horizontal = 0;  //Used to store the horizontal move direction. 
      int vertical = 0;  //Used to store the vertical move direction. 

      //Check if we are running either in the Unity editor or in a standalone build. 
      #if UNITY_STANDALONE || UNITY_WEBPLAYER 

      //Get input from the input manager, round it to an integer and store in horizontal to set x axis move direction 
      horizontal = (int) (Input.GetAxisRaw ("Horizontal")); 

      //Get input from the input manager, round it to an integer and store in vertical to set y axis move direction 
      vertical = (int) (Input.GetAxisRaw ("Vertical")); 

      //Check if moving horizontally, if so set vertical to zero. 
      if(horizontal != 0) 
      { 
       vertical = 0; 
      } 

      //Check if we have a non-zero value for horizontal or vertical 
      if (horizontal != 0 || vertical != 0) 
      { 
       //Call AttemptMove passing in the generic parameter Wall, since that is what Player may interact with if they encounter one (by attacking it) 
       //Pass in horizontal and vertical as parameters to specify the direction to move Player in. 
       AttemptMove<Wall> (horizontal, vertical); 
      } 
     } 

     //AttemptMove overrides the AttemptMove function in the base class MovingObject 
     //AttemptMove takes a generic parameter T which for Player will be of the type Wall, it also takes integers for x and y direction to move in. 
     protected override void AttemptMove <T> (int xDir, int yDir) 
     { 
      //Every time player moves, subtract from health points total. 
      health--; 

      //Update health text display to reflect current score. 
      healthText.text = "Health: " + health; 

      //Call the AttemptMove method of the base class, passing in the component T (in this case Wall) and x and y direction to move. 
      base.AttemptMove <T> (xDir, yDir); 

      //Hit allows us to reference the result of the Linecast done in Move. 
      RaycastHit2D hit; 

      //If Move returns true, meaning Player was able to move into an empty space. 
      if (Move (xDir, yDir, out hit)) 
      { 
       //Call RandomizeSfx of SoundManager to play the move sound, passing in two audio clips to choose from. 
       SoundManager.instance.RandomizeSfx (moveSound1, moveSound2); 
      } 

      //Since the player has moved and lost health points, check if the game has ended. 
      CheckIfGameOver(); 

      //Set the playersTurn boolean of GameManager to false now that players turn is over. 
      GameManager.instance.playersTurn = false; 
     } 


     //OnCantMove overrides the abstract function OnCantMove in MovingObject. 
     //It takes a generic parameter T which in the case of Player is a Wall which the player can attack and destroy. 
     protected override void OnCantMove <T> (T component) 
     { 
      //Set hitWall to equal the component passed in as a parameter. 
      Wall hitWall = component as Wall; 

      //Call the DamageWall function of the Wall we are hitting. 
      hitWall.DamageWall (wallDamage); 

      //Set the attack trigger of the player's animation controller in order to play the player's attack animation. 
      animator.SetTrigger ("playerAttack"); 
     } 


     //OnTriggerEnter2D is sent when another object enters a trigger collider attached to this object (2D physics only). 
     private void OnTriggerEnter2D (Collider2D other) 
     { 
      //Check if the tag of the trigger collided with is Exit. 
      if(other.tag == "Exit") 
      { 
       //Invoke the Restart function to start the next level with a delay of restartLevelDelay (default 1 second). 
       Invoke ("Restart", restartLevelDelay); 

       //Disable the player object since level is over. 
       enabled = false; 
      } 

      //Check if the tag of the trigger collided with is GoodFood. 
      else if(other.tag == "GoodFood") 
      { 
       //Add pointsPerGoodFood to the players current health total. 
       health += pointsPerGoodFood; 

       //Update healthText to represent current total and notify player that they gained points 
       healthText.text = "+" + pointsPerGoodFood + " Health: " + health; 

       //Call the RandomizeSfx function of SoundManager and pass in two eating sounds to choose between to play the eating sound effect. 
       SoundManager.instance.RandomizeSfx (eatSound1, eatSound2); 

       //Disable the GoodFood object the player collided with. 
       other.gameObject.SetActive (false); 
      } 

      //Check if the tag of the trigger collided with is OkayFood. 
      else if(other.tag == "OkayFood") 
      { 
       //Add pointsPerOkayFood to players health points total 
       health += pointsPerOkayFood; 

       //Update healthText to represent current total and notify player that they gained points 
       healthText.text = "+" + pointsPerOkayFood + " Health: " + health; 

       //Call the RandomizeSfx function of SoundManager and pass in two eating sounds to choose between to play the eating sound effect. 
       SoundManager.instance.RandomizeSfx (eatSound3, eatSound4); 

       //Disable the OkayFood object the player collided with. 
       other.gameObject.SetActive (false); 
      } 
     } 


     //Restart reloads the scene when called. 
     private void Restart() 
     { 
      //Load the last scene loaded, in this case Main, the only scene in the game. 
      SceneManager.LoadScene(0); 
     } 


     //LoseHealth is called when an enemy attacks the player. 
     //It takes a parameter loss which specifies how many points to lose. 
     public void LoseHealth (int loss) 
     { 
      //Set the trigger for the player animator to transition to the playerHit animation. 
      animator.SetTrigger ("playerHit"); 

      //Subtract lost health points from the players total. 
      health -= loss; 

      //Update the health display with the new total. 
      healthText.text = "-"+ loss + " Health: " + health; 

      //Check to see if game has ended. 
      CheckIfGameOver(); 
     } 


     //CheckIfGameOver checks if the player is out of health points and if so, ends the game. 
     private void CheckIfGameOver() 
     { 
      //Check if health point total is less than or equal to zero. 
      if (health <= 0) 
      { 
       //Call the PlaySingle function of SoundManager and pass it the gameOverSound as the audio clip to play. 
       SoundManager.instance.PlaySingle (gameOverSound); 

       //Stop the background music. 
       SoundManager.instance.musicSource.Stop(); 

       //Call the GameOver function of GameManager. 
       GameManager.instance.GameOver(); 
      } 
     } 
    } 
} 

Answer 1

Vérifiez dans l'inspecteur si la santé La variable de texte est liée à un objet texte d'interface utilisateur. Le lien ne doit pas être défini (None) ou autrement rompu (Missing) si vous obtenez cette exception.