import java.util.ArrayList;


// This class provides a demo of static intializers.

// In the example below, there are three static arraylists, each
// of which is initalized in a different way.

// The first ArrayList, elPulpoMechanical, is initialized using a 
// static initalizer block. The seecond ArrayList, jellyfishHeaven,
// is initailized using a call to a static method.

// These two initializations are performed at the time that the first
// instance of this class is instantiated. Neither of these initializations
// is ever called again (well at least until this class is reloaded by
// anther ClassLoader, for example when the 'java' command is called by the
// operation system again).

// The third ArrayList, rydeen, is initialized using an initalizer block.
// Unlike the static initialization techniques discussed above, this code is
// called again EVERY TIME a new StaticInitialization is performed. As Oracle puts
// it, "The Java compiler copies initializer blocks into every constructor."

// The fourth ArrayList, zebra, is initialized using the constructor. Naturally,
// this code will execute every time that a StaticInitializationDemo object is
// instantiated (though unlike rydeen, the code is written to prevent the
// static variable fromy being set more than once).

// Bottom line: We recommend that you use one of the first two approaches!


public class StaticInitializationDemo {
	public static ArrayList<String> elPulpoMechanical;
	public static ArrayList<String> jellyfishHeaven = createArrayList(10);
	public static ArrayList<String> rydeen;
	public static ArrayList<String> zebra;

	static {
		elPulpoMechanical = new ArrayList<String>();
		elPulpoMechanical.add("Watskeburt?!");
	}

	private static ArrayList<String> createArrayList(int numStrings)
	{
		ArrayList<String> tempArrayList = new ArrayList<String>();
		for (int i = 0; i < numStrings; i++)
			tempArrayList.add("Sweet jellyfish!");

		return tempArrayList;
	}

	{
		rydeen = new ArrayList<String>();
		rydeen.add("Watskeburt?!");
	}

	public StaticInitializationDemo()
	{
		if (zebra == null)
			zebra = createArrayList(10);
	}

}