koobas.hobune.stream
Checking if int is !null not working ? Strange...
Hi,
So I was just testing binary save and load in Unity when i encountered this problem. I am trying to save "coins" variable but in the beginning the number of coins is zero or null and i tried to put a condition "if coins != null { LoadPlayerProgress(); } else { coins = 5; SavePlayerProgress;}". The thing is that when i run the game on the editor the ui text where I display coins shows zero coins and not five. Here I am pasting the codes so you can check it by yourself because its really simple but it just doesn't work properly.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
using System.Runtime.Serialization.Formatters.Binary;
using System.IO;
public class SaveLoad : MonoBehaviour {
public static SaveLoad instance;
void Awake()
{
if (instance == null) {
DontDestroyOnLoad (gameObject);
instance = this;
}
else if(instance != this)
{
Destroy (gameObject);
}
}
public void Save()
{
BinaryFormatter bf = new BinaryFormatter ();
FileStream file = File.Create (Application.persistentDataPath + "/playInfo.sav");
PlayerData data = new PlayerData ();
data.coins = SaveLoad.instance.GetComponent<ButtonControl>().coins;
bf.Serialize (file, data);
file.Close ();
}
public void Load()
{
if (File.Exists (Application.persistentDataPath + "/playInfo.sav"))
{
BinaryFormatter bf = new BinaryFormatter ();
FileStream file = File.Open (Application.persistentDataPath + "/playInfo.sav", FileMode.Open);
PlayerData data = (PlayerData)bf.Deserialize (file);
file.Close ();
SaveLoad.instance.GetComponent<ButtonControl>().coins = data.coins;
}
}
[Serializable]
class PlayerData
{
public int coins;
}
}
Here is the other script that contains a function for adding coins using a button. In the editor i have also added two other buttons to save and load the progress.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class ButtonControl : MonoBehaviour {
[HideInInspector]
public int coins;
public Text text;
// Use this for initialization
void Start ()
{
if (coins != null)
{
SaveLoad.instance.Load ();
}
else
{
coins = 5;
SaveLoad.instance.Save ();
}
}
// Update is called once per frame
void Update () {
text.text = coins.ToString ();
}
public void AddCoins()
{
coins += 100;
}
}
Also, I erased the saved data in the persistent path where unity store the savings and still coins text shows zero coins and not 5.
If I use a nullable int "int? coins;" and put the same condition, coins text does show 5 coins and not zero but there is another problem because when I add some coins and click save and after this I exit the game and then run it again the save doesn't load and still shows 5 coins. You should also create three buttons where one of them should contain the AddCoins() function and the other two the save and load from SaveLoad class. This is strange. It is better to test this problem with my codes by yourself and see where the problem is.
Thank you, Gerald.
int cannot contain null unless it's a nullable, you can use some nifty generic method to check if it contains the default value like so if its not a nullable int:
public static class TypeHelper
{
public static bool IsDefault<T>(this T val)
{
return EqualityComparer<T>.Default.Equals(val,default(T));
}
}
Now you can use it as follows:
int abc = 5;
if (abc.IsDefault())
That's just a complicated way of doing:
if (coins == 0)
default(int) is simply 0.
ps: you have a typo in your method. You named your parameter "val" but you used "obj" in your code which is not defined. Also you didn't declare you method as extension method, so you can't use it the way you did. You have to use the "this" modifier on the first parameter to turn your method into an extension method.
I also tried "if (coins == 0) { coins = 5; Save(); } else { Load() }", and this condition worked but when I added some other coins and saved the game through the function save and I quit the game on the editor and then run the game again, the coins where again 5 and not like the last save which was more than 5 coins. Anyway, I have no idea why this happens. :P
Yes but this works on keyvaluepairs and other types aswel which does make it useable :) $$anonymous$$y bad for the missing code, I was in a hurry. Corrected it
Start is called only when the prefab or object is made.
I am assuming both of these scripts are on a prefab of some sort.
If your prefab has a coin value that is anything other than 0 it will load from a file
If it is 0 you will set coins to 5 and save that to a file.
What are you trying to do exactly?
You never save after start so when you add coins it will never save. Try saving in your add coin function after you add the coins.
I have put these scripts on Camera object just for testing because my game is a lot more complex than these two scripts but the idea is the same. I am just trying to put a condition before the game save loads from the binary file that if coins variable is null which means that if the game hasn't been played or is being played for the first time, then coins = 5, else load the game save,. Now the problem is that when the game hasn't been played and I open it for the first time the coins is still zero and not five and after I add some coins with that function using a button, the coins add as they should and after I hit the save button to save the coins and then exit on the editor, and then play again, the coins are still zero...You can try it by yourself.
But you don't change the right variable if you want to change the PlayerData class you need to change it there not a local variable called coins.
$$anonymous$$aybe I am a little bit confused but I solved the problem I had with my current game. I am leaving this post open just in case if I encounter any problem later again. Thank's for your support Orami. ;)
