Reading from a file
- Game Development course
- Advanced
- Lesson 22/71
- 4 min
Learn to read saved data with File.ReadAllText.
File Checking and File.ReadAllText
Checking whether a file exists on disk with File.Exists(path) before reading prevents runtime exceptions. If verified, calling File.ReadAllText(path) retrieves the full file content as a string.
using System.IO;
if (File.Exists(path)) {
string json = File.ReadAllText(path);
}If the file is not found, a fresh profile initialized with default values can be created instead.
Deserialization: JsonUtility.FromJson
Rebuilding a live C# object from a retrieved JSON string is known as deserialization. The generic JsonUtility.FromJson<T>(json) method constructs an instance of type T and fills its fields.
// Restoring an object from a JSON string
PlayerData data = JsonUtility.FromJson<PlayerData>(json);
Debug.Log("Loaded health: " + data.health);This seamlessly restores the player's health, score, and items back into active memory.
Practice Save file reading flow
Define a Start method. Inside, declare bool dosyaVar = true; and print "Kayit dosyasi bulundu: " + dosyaVar to the console.
Starter code
using UnityEngine;
public class SaveReader : MonoBehaviour
{
// Start icinde dosyaVar degiskenini tanimla ve yazdir
}Sample solution
using UnityEngine;
public class SaveReader : MonoBehaviour
{
void Start()
{
bool dosyaVar = true;
Debug.Log("Kayit dosyasi bulundu: " + dosyaVar);
}
}Expected output
Kayit dosyasi bulundu: True
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which method is used to safely verify the existence of a file before attempting to open it?
- File.Find(path)
- File.HasFile(path)
- File.Exists(path) Correct answer
- File.Validate(path)
Explanation: The System.IO.File.Exists(path) method returns a boolean (true/false) indicating whether a file exists at the given path.
2 Instantiate object from JSON
PlayerData data = JsonUtility.____<PlayerData>(jsonString);PlayerData data = JsonUtility.FromJson<PlayerData>(jsonString);Explanation: The 'FromJson' method is invoked to convert JSON text into an instance of the specified C# type.
3 File reading concepts
| Term | Meaning |
|---|---|
File.Exists |
Checks if the file exists on disk |
File.ReadAllText |
Reads all text from the file |
FromJson |
Converts JSON text into a C# object |
Deserialization |
Process of restoring an object from text |