enum Tetrominoes {
    SBlock(new Point[]{new Point(-1,0), new Point(0,0), new Point(-2,1),
        new Point(-1,1)}),
    ZBlock(new Point[]{new Point(-2,0), new Point(-1,0), new Point(-1,1),
        new Point(0,1)}),
    JBlock(new Point[]{new Point(-2,0), new Point(-2,1), new Point(-1,1),
        new Point(0,1)}),
    LBlock(new Point[]{new Point(0,0), new Point(-2,1), new Point(-1,1),
        new Point(0,1)}),
    OBlock(new Point[]{new Point(-1,0), new Point(0,0), new Point(-1,1),
        new Point(0,1)}),
    TBlock(new Point[]{new Point(-1,0), new Point(-2,1), new Point(-1,1),
        new Point(0,1)}),
    IBlock(new Point[]{new Point(-2,0), new Point(-1,0), new Point(0,0),
        new Point(1,0)});

    final Point[] relativeStartPos;
    Point[] relativeCurrPos;

    private Tetrominoes(Point[] relativeStartPos) {
        this.relativeStartPos = relativeStartPos;
        relativeCurrPos = new Point[4];
        resetPos();
    }

    void resetPos() {
        relativeCurrPos = relativeStartPos.clone();
    }

    void down() {
        for(int i = 0; i < 4; i++) {
            (relativeCurrPos[i].y)++;
        }
    }
}

// ArrayList declaration appearing earlier in code
private ArrayList<Integer> randBag = new ArrayList<Integer>();

void selectBlock() {
    Tetrominoes[] tetro = Tetrominoes.values();
    if(randBag.isEmpty()) {
        Collections.addAll(randBag, 0, 1, 2, 3, 4, 5, 6);
        Collections.shuffle(randBag);
    }
    currentBlock = tetro[nextBlock.ordinal()];
    currentBlock.resetPos();

    randBag.remove(0);
    if(randBag.isEmpty()) {
        Collections.addAll(randBag, 0, 1, 2, 3, 4, 5, 6);
        Collections.shuffle(randBag);
    }
    nextBlock = tetro[randBag.get(0)];
    nextBlock.resetPos();
}