Singleton Class in Java

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
}

References
https://www.geeksforgeeks.org/singleton-class-java/
https://www.baeldung.com/java-singleton