Singleton Pattern

You may have noticed that both MolfileSmilesConverterAdapterA and MolfileSmilesConverterAdapterB have a private constructor and a static getlnstance() method that returns an instance of the class. Yes, this is the GoF Singleton Pattern (Gamma et al., 1995). 

The Singleton Pattern ensures that a class has only one instance, and it provides a global point of access to it. 

Tire reason Singleton Pattern is used in these two classes is that only one instance of each is needed in tire entire JVM, because there is no instance variable in these two classes—they are stateless. Limiting the number of objects that can be created is a way to increase runtime efficiency and achieve good performance because object creation and garbage collection are two of the most expensive operations in JVM. The Singleton Pattern is implemented by creating a private constructor—this makes sure no instance of the class can be created outside the class itself, a static final instance of the class itself, and a public static method that returns the instance. As the constructor is private, none of its clients can instantiate the class directly. Instead, they have to use the public static method getlnstance() to retrieve the one and only instance of tire class. 

Some reactivity patterns of both the hydrazine and methylhydrazine complexes are given by Singleton and coworkers.5... 

Bomb products, rocket reentry bumup products, meteoritic dust, and other trace constituents will be redistributed rapidly within the mesosphere by large scale circulation, by eddy diffusion and, for particles of significant size, by gravitational sedimentation as well (1). Murgatroyd and Singleton (32) discuss the circulation of the mesosphere and indicate a meridional pattern, with ascent over the summer pole, descent over the winter pole, and a well defined flow from the summer hemisphere to the winter hemisphere above 50 km., with speeds of the order of meters sec."1 horizontally and cm. sec."1 vertically. 

A secondary screen using real-time PCR was used to identify candidate polyketide synthases whose expression pattern correlated with the accumulation of sorgoleone. Gene-specific primers were designed for the 5 contigs and singletons representing the polyketide synthases (Table I). Real time PCR was... 

The graphical representation of a node is a combination of shape and perimeter style and optionally of color. All nodes are placed at the corners of a square pattern or a segment (case of singletons), with the exception of the activity (cf. Chapter 7). 

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