A simple Tetris clone written in Java

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Tetris.java

// Tetris.java
//
// Written in 2013 by Johannes Holzfuß <johannes@holzfuss.name>
//
// To the extent possible under law, the author(s) have dedicated all copyright
// and related and neighboring rights to this software to the public domain
// worldwide. This software is distributed without any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication along
// with this software. If not, see
// <http://creativecommons.org/publicdomain/zero/1.0/>.

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.Collections;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Tetris extends JPanel {

	private static final long serialVersionUID = -8715353373678321308L;

	private final Point[][][] Tetraminos = {
			// I-Piece
			{
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(3, 1) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(1, 3) },
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(3, 1) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(1, 3) }
			},
			
			// J-Piece
			{
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(2, 0) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(2, 2) },
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(0, 2) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(0, 0) }
			},
			
			// L-Piece
			{
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(2, 2) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(0, 2) },
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(0, 0) },
				{ new Point(1, 0), new Point(1, 1), new Point(1, 2), new Point(2, 0) }
			},
			
			// O-Piece
			{
				{ new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
				{ new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
				{ new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) },
				{ new Point(0, 0), new Point(0, 1), new Point(1, 0), new Point(1, 1) }
			},
			
			// S-Piece
			{
				{ new Point(1, 0), new Point(2, 0), new Point(0, 1), new Point(1, 1) },
				{ new Point(0, 0), new Point(0, 1), new Point(1, 1), new Point(1, 2) },
				{ new Point(1, 0), new Point(2, 0), new Point(0, 1), new Point(1, 1) },
				{ new Point(0, 0), new Point(0, 1), new Point(1, 1), new Point(1, 2) }
			},
			
			// T-Piece
			{
				{ new Point(1, 0), new Point(0, 1), new Point(1, 1), new Point(2, 1) },
				{ new Point(1, 0), new Point(0, 1), new Point(1, 1), new Point(1, 2) },
				{ new Point(0, 1), new Point(1, 1), new Point(2, 1), new Point(1, 2) },
				{ new Point(1, 0), new Point(1, 1), new Point(2, 1), new Point(1, 2) }
			},
			
			// Z-Piece
			{
				{ new Point(0, 0), new Point(1, 0), new Point(1, 1), new Point(2, 1) },
				{ new Point(1, 0), new Point(0, 1), new Point(1, 1), new Point(0, 2) },
				{ new Point(0, 0), new Point(1, 0), new Point(1, 1), new Point(2, 1) },
				{ new Point(1, 0), new Point(0, 1), new Point(1, 1), new Point(0, 2) }
			}
	};
	
	private final Color[] tetraminoColors = {
		Color.cyan, Color.blue, Color.orange, Color.yellow, Color.green, Color.pink, Color.red
	};
	
	private Point pieceOrigin;
	private int currentPiece;
	private int rotation;
	private ArrayList<Integer> nextPieces = new ArrayList<Integer>();

	private long score;
	private Color[][] well;
	
	// Creates a border around the well and initializes the dropping piece
	private void init() {
		well = new Color[12][24];
		for (int i = 0; i < 12; i++) {
			for (int j = 0; j < 23; j++) {
				if (i == 0 || i == 11 || j == 22) {
					well[i][j] = Color.GRAY;
				} else {
					well[i][j] = Color.BLACK;
				}
			}
		}
		newPiece();
	}
	
	// Put a new, random piece into the dropping position
	public void newPiece() {
		pieceOrigin = new Point(5, 2);
		rotation = 0;
		if (nextPieces.isEmpty()) {
			Collections.addAll(nextPieces, 0, 1, 2, 3, 4, 5, 6);
			Collections.shuffle(nextPieces);
		}
		currentPiece = nextPieces.get(0);
		nextPieces.remove(0);
	}
	
	// Collision test for the dropping piece
	private boolean collidesAt(int x, int y, int rotation) {
		for (Point p : Tetraminos[currentPiece][rotation]) {
			if (well[p.x + x][p.y + y] != Color.BLACK) {
				return true;
			}
		}
		return false;
	}
	
	// Rotate the piece clockwise or counterclockwise
	public void rotate(int i) {
		int newRotation = (rotation + i) % 4;
		if (newRotation < 0) {
			newRotation = 3;
		}
		if (!collidesAt(pieceOrigin.x, pieceOrigin.y, newRotation)) {
			rotation = newRotation;
		}
		repaint();
	}
	
	// Move the piece left or right
	public void move(int i) {
		if (!collidesAt(pieceOrigin.x + i, pieceOrigin.y, rotation)) {
			pieceOrigin.x += i;	
		}
		repaint();
	}
	
	// Drops the piece one line or fixes it to the well if it can't drop
	public void dropDown() {
		if (!collidesAt(pieceOrigin.x, pieceOrigin.y + 1, rotation)) {
			pieceOrigin.y += 1;
		} else {
			fixToWell();
		}	
		repaint();
	}
	
	// Make the dropping piece part of the well, so it is available for
	// collision detection.
	public void fixToWell() {
		for (Point p : Tetraminos[currentPiece][rotation]) {
			well[pieceOrigin.x + p.x][pieceOrigin.y + p.y] = tetraminoColors[currentPiece];
		}
		clearRows();
		newPiece();
	}
	
	public void deleteRow(int row) {
		for (int j = row-1; j > 0; j--) {
			for (int i = 1; i < 11; i++) {
				well[i][j+1] = well[i][j];
			}
		}
	}
	
	// Clear completed rows from the field and award score according to
	// the number of simultaneously cleared rows.
	public void clearRows() {
		boolean gap;
		int numClears = 0;
		
		for (int j = 21; j > 0; j--) {
			gap = false;
			for (int i = 1; i < 11; i++) {
				if (well[i][j] == Color.BLACK) {
					gap = true;
					break;
				}
			}
			if (!gap) {
				deleteRow(j);
				j += 1;
				numClears += 1;
			}
		}
		
		switch (numClears) {
		case 1:
			score += 100;
			break;
		case 2:
			score += 300;
			break;
		case 3:
			score += 500;
			break;
		case 4:
			score += 800;
			break;
		}
	}
	
	// Draw the falling piece
	private void drawPiece(Graphics g) {		
		g.setColor(tetraminoColors[currentPiece]);
		for (Point p : Tetraminos[currentPiece][rotation]) {
			g.fillRect((p.x + pieceOrigin.x) * 26, 
					   (p.y + pieceOrigin.y) * 26, 
					   25, 25);
		}
	}
	
	@Override 
	public void paintComponent(Graphics g)
	{
		// Paint the well
		g.fillRect(0, 0, 26*12, 26*23);
		for (int i = 0; i < 12; i++) {
			for (int j = 0; j < 23; j++) {
				g.setColor(well[i][j]);
				g.fillRect(26*i, 26*j, 25, 25);
			}
		}
		
		// Display the score
		g.setColor(Color.WHITE);
		g.drawString("" + score, 19*12, 25);
		
		// Draw the currently falling piece
		drawPiece(g);
	}

	public static void main(String[] args) {
		JFrame f = new JFrame("Tetris");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setSize(12*26+10, 26*23+25);
		f.setVisible(true);
		
		final Tetris game = new Tetris();
		game.init();
		f.add(game);
		
		// Keyboard controls
		f.addKeyListener(new KeyListener() {
			public void keyTyped(KeyEvent e) {
			}
			
			public void keyPressed(KeyEvent e) {
				switch (e.getKeyCode()) {
				case KeyEvent.VK_UP:
					game.rotate(-1);
					break;
				case KeyEvent.VK_DOWN:
					game.rotate(+1);
					break;
				case KeyEvent.VK_LEFT:
					game.move(-1);
					break;
				case KeyEvent.VK_RIGHT:
					game.move(+1);
					break;
				case KeyEvent.VK_SPACE:
					game.dropDown();
					game.score += 1;
					break;
				} 
			}
			
			public void keyReleased(KeyEvent e) {
			}
		});
		
		// Make the falling piece drop every second
		new Thread() {
			@Override public void run() {
				while (true) {
					try {
						Thread.sleep(1000);
						game.dropDown();
					} catch ( InterruptedException e ) {}
				}
			}
		}.start();
	}
}

no game over?

Hello DataWraith,

As a Software Engineering student at McMaster University, I had chosen to work with your project (Tetris) for one of my assignments.
The main task is to document the source code according to given guidelines. I was hoping that you would be able to revise my proposed comments and documentation and potentially merge those changes with your current project. I am sending you this as a comment as it is not possible to create pull requests on GitHub Gist, surprisingly. The changes I propose can be found on my public fork under this project.

Thank you for your time, and hope that you accept to merge.

Regards,
Kareem Abdel Mesih

Good day. The fork that I created adds additional functionality to your Tetris game, and with it you'll be able to see the theoretical position of the moving block. You'll probably learn something from the code I've written, for I'm also making my own Tetris game.

I could see improvements that could be added like adding a 'Game Over' feature, but your coding cleanliness is exceptional, and I even tried to implement the 'well array' idea to my own app.

Thanks, and I would love it if you could merge this.

Hi, I can't seem to run this on bluej

The tetr-a-mino is a typo. It's called tetr-o-mino, though we use the word tetra for 4-something.

Using a Thread is not good for java swing, especially if you are messing around with the user interface. I suggest you use a java.swing.timer for this.

Very cool!

Thanks

https://www.youtube.com/watch?v=KjEaD0KyL0w&t=1345s they made video of your code

I've actually hacked up similar thing just without swing it runs directly in Terminal https://github.com/MShel/term_tetris

Hello! I was wondering if I could compile the game and make it downloadable on my website? I will give you credits and also I can add music to the game so it feels even more like Tetris.

Oh wow, I completely forgot I had this gist.

I've gone ahead and changed the license to CC0. That makes it clear that you can do whatever you want with the code.

Hello, I'm a Computer Science Junior at the University of Maryland. As part of the final project of a course regarding Github use, I was required to find an open-source project and make changes to it. I chose to modify your Tetris program for this requirement. In my public Fork, I have implemented several new abilities, mostly inspired by the additional functions provided in the online Tetris version found at Tetris.com/play-tetris. These include the ability to "store" blocks in order to selectively replace the currently dropping block, a scaling difficulty system in which blocks drop faster based on the player's current score at increments of 1000 points, the ability to make a "hard drop" which instantly drops the current block to the bottom of the screen in exchange for bonus points, and a (partially implemented) game over/new game screen. Minor changes include a rescaled UI with level, score, and stored piece information displayed in black space above the board, changing the J-piece's starting rotation so that it begins in contact with the top of the board, de-threading the game-step system in main(), switching the colors of the J and L pieces, and changing keybinds to match those in the online version. Furthermore, I have added several methods that provide basic functions, including dropping a selected piece, returning the character representation of a piece (J, L, T, Z, S, I, O), and the implementation for the hard-drop ability. I hope that other users of this repository might find some of these added functions useful to their own versions.

Update: I've fully implemented the functionality of a game-over system. If the player "loses" and their high score is higher than the lowest high score, it is inserted into the high-scores list in the appropriate place. If they choose to play again (green button) then the game resets while keeping the updated high-scores list. If they choose to exit the game, then the high-scores list is written to the separate highscores.txt file. If they start another game later, the new high-scores list within the game is generated from this file. This allows for scores to be retained throughout multiple game sessions. Future plans are focused around improving the game over UI and possibly changing the simple random generation algorithm to something more reactive to the current game state. Some debugging print statements remain and are commented out - I expect to need them for future work, but can be removed if desired.