what is singleton class code example

Example 1: java singleton

- A private constructor
- A static field containing its only instance
- A static factory method for obtaining the instance

public final class ClassSingleton 
{

    private static ClassSingleton INSTANCE;
    private String info = "Initial info class";
    
    private ClassSingleton() 
	{        
    }
    
    public static ClassSingleton getInstance() 
	{
        if(INSTANCE == null) 
        {
            INSTANCE = new ClassSingleton();
        }
  
        return INSTANCE;
    }

    // getters and setters
}

                      =============Usage============
                        

To use our ClassSingleton, we simply need to get the instance statically:

ClassSingleton classSingleton1 = ClassSingleton.getInstance();

System.out.println(classSingleton1.getInfo()); //Initial class info

ClassSingleton classSingleton2 = ClassSingleton.getInstance();
classSingleton2.setInfo("New class info");

System.out.println(classSingleton1.getInfo()); //New class info
System.out.println(classSingleton2.getInfo()); //New class info

Example 2: singelton code

using UnityEngine;

public class SingeltonObject : MonoBehaviour
{

    void Awake()
    {
        SetUpSingelton();   
    }

    private void SetUpSingelton()
    {
        if (FindObjectsOfType(GetType()).Length > 1)
        {
            Destroy(gameObject);
        }
        else
        {
            DontDestroyOnLoad(gameObject);
        }
    }
}