The program is run using the main in SingletonGUI.java.

Left and right arrows to move the piece around.
Up arrow to rotate, down arrow to soft drop, space bar to hard drop.
Start a new game by clicking the new game button, switch gravity type in the menu.



The design patterns used are:

Singleton.
A SingletonGUI is responsible for creating the Tetris object and that only one is created.
This class then provides a way to access the object without needing to instantiate it.

    //Tetris
    //Singleton design pattern instance of Tetris
    public static Tetris instance = new Tetris();

    //Returns the instance of Tetris
    public static Tetris getInstance(){
        return instance;
    }

    //SingletonGUI
    public static void main(String[] args) {
        //Get the only object available
        Tetris object = Tetris.getInstance();
    }


Factory.
We create an object without directly exposing the logic, and all subclasses are
referred to using this main objects common instance, giving the user the ability
of making universal calls.

//Tetris
switch (currentColor) {
                    //I
                    case 1: {
                        currentPiece = new PieceI();
                        piece = 'I';
                        nextPiece.setText("     Next Piece: " + piece);
                        break;
                    }
                    //T
                    case 2: {
                        currentPiece = new PieceT();
                        piece = 'T';
                        nextPiece.setText("     Next Piece: " + piece);
                        break;
                    }

                    ..etc

The rest of the program then refers to the polymorphic class using common functions for the rest of its
life cycle, irregardless of which specific subclass was actually instantiated.