- 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

Popularity 10/10 Helpfulness 4/10 Language java

Source: Grepper

Tags: java

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Contributed on Jan 08 2021

Mustafa Mbari

0 Answers Avg Quality 2/10

java singleton implementation

Comment

public class SingletonClass {
    private static final SingletonClass SINGLE_INSTANCE = new SingletonClass();
    private SingletonClass() {}
  public static SingletonClass getInstance() {
      return SINGLE_INSTANCE;
    }
}

Popularity 10/10 Helpfulness 4/10 Language java

Source: dzone.com

Tags: implementation impl

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Contributed on Feb 20 2020

Java Hater

0 Answers Avg Quality 2/10

java singleton

Comment

public class SingletonOnDemand {
	
	private SingletonOnDemand () {}
	private static class Singleton {
		private static final SingletonOnDemand instance = new SingletonOnDemand();
	}
	
	public static SingletonOnDemand getInstance () {
		System.out.println("create instance");
		return Singleton.instance;
	}
}

Popularity 10/10 Helpfulness 3/10 Language java

Source: Grepper

Tags: java

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Contributed on May 18 2020

Super Stoat

0 Answers Avg Quality 2/10

java singleton

Comment

public class DB {
    // champs de l'objet

    private DB(){
        // initialisation des champs
    }

    private static final DB INSTANCE = new DB();
    public static DB getInstance(){
        return INSTANCE;
    }
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java

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Contributed on Dec 16 2021

Silly Sheep

0 Answers Avg Quality 2/10

java singleton

Comment

public final class SomeSingleton {
   public static final SomeSingleton INSTANCE;

   private SomeSingleton() {
      INSTANCE = (SomeSingleton)this;
      System.out.println("init complete");
   }

   static {
      new SomeSingleton();
   }
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java

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Contributed on Apr 21 2021

VasteMonde

0 Answers Avg Quality 2/10

java Singleton

Comment

public class Singleton {
    // Private static variable to hold the single instance of the class
    private static Singleton instance;

    // Private constructor to prevent instantiation from outside the class
    private Singleton() {
        // Initialization code, if needed
    }

    // Public static method to get the single instance of the class
    public static Singleton getInstance() {
        // Lazy initialization: create the instance if it doesn't exist yet
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }

    // Other methods and variables can be added here as needed
}

Popularity 5/10 Helpfulness 2/10 Language java

Source: chat.openai.com

Tags: java singleton

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Contributed on Jan 28 2024

Savindi Dadallage

0 Answers Avg Quality 2/10

Singleton pattern with java example

Comment

public class Singleton {
    // Private static instance variable to hold the single instance
    private static Singleton instance;

    // Private constructor to prevent instantiation from other classes
    private Singleton() {
        // Initialization code, if needed
    }

    // Public static method to get the single instance
    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }

    // Other methods of the Singleton class
    public void showMessage() {
        System.out.println("Hello, I am a Singleton!");
    }
}

Popularity 9/10 Helpfulness 2/10 Language java

Source: chat.openai.com

Tags: java singleton

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Contributed on Aug 11 2023

Hilarious Heron

0 Answers Avg Quality 2/10

Have you used Singleton design pattern in your Java project?

Comment

Yes. Singleton is one of the most popular design patterns in

enterprise level Java applications. Almost in every project we see

some implementation of Singleton.

With Singleton pattern we can be sure that there is only one instance

of a class at any time in the application.

This helps in storing properties that have to be used in the

application in a unique location

public class SingletonSerializedTest {

    public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
        SerializedSingleton instanceOne = SerializedSingleton.getInstance();
        ObjectOutput out = new ObjectOutputStream(new FileOutputStream(
                "filename.ser"));
        out.writeObject(instanceOne);
        out.close();

        // deserialize from file to object
        ObjectInput in = new ObjectInputStream(new FileInputStream(
                "filename.ser"));
        SerializedSingleton instanceTwo = (SerializedSingleton) in.readObject();
        in.close();

        System.out.println("instanceOne hashCode="+instanceOne.hashCode());
        System.out.println("instanceTwo hashCode="+instanceTwo.hashCode());

    }

}

https://www.digitalocean.com/community/tutorials/java-singleton-design-pattern-best-practices-examples

Popularity 9/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java

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Contributed on Feb 10 2023

Pragya Keshap

0 Answers Avg Quality 2/10

Java Singleton pattern

Comment

public class Singleton {
    private static Singleton instance;

    private Singleton() {}

    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

Popularity 9/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java singleton

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Contributed on Jul 26 2023

Cabs

0 Answers Avg Quality 2/10

java singleton design pattern

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