How to implement a singleton pattern?

Create a public class having a private constructor. Private constructor ensures that the object cannot be created outside of the class.

Create a private static variable of the type Class itself.

Create a public static method e.g. getInstance() that returns the reference of the static variable, if the static variable is null then create a object for the class.

package org.javatutorials.designpatterns;

//Step 1
public class SingletonPattern {

	//Step 2
	private static SingletonPattern mySingletonObj;

	private SingletonPattern() {

	}

	public static SingletonPattern getInstance() {

		if (mySingletonObj == null) {
			mySingletonObj = new SingletonPattern();

		}

		return mySingletonObj;
	}
}

Earn bitcoins upto $250 (free), invest in other Cryptocurrencies when you signup with blockfi. Use the referral link: Signup now and earn!

Using BlockFi, don't just buy crypto - start earning on it. Open an interest account with up to 8.6% APY, trade currencies, or borrow money without selling your assets.

Join CoinBase! We'll both receive $10 in free Bitcoin when they buy or sell their first $100 on Coinbase! Available in India also. Use the referral Join coinbase!

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.