Robots/Java

Code

Works with: Java version 8

<lang java>import java.awt.*; import static java.awt.BasicStroke.*; import java.awt.event.*; import static java.lang.Math.abs; import static java.lang.String.format; import java.util.Random; import javax.swing.*;

public class Robots extends JPanel {

   enum Grid {
       Player("@"), Robot("+"), Scrap("*"), Mark("~");

       Grid(String s) {
           symbol = s;
       }
       final String symbol;
   }

   final static int[][] dirs = {{-1, 1}, {0, 1}, {1, 1}, {-1, 0}, {1, 0},
   {-1, -1}, {0, -1}, {1, -1}};

   final static Random rand = new Random();

   final int nRows;
   final int nCols;

   Grid[][] grid;
   int playerRow, playerCol, score, hiScore, level;
   boolean gameOver = true;
   Stroke dash;

   public Robots() {
       setPreferredSize(new Dimension(800, 650));
       setBackground(Color.white);
       setForeground(Color.lightGray);
       setFont(new Font("SansSerif", Font.PLAIN, 18));
       setFocusable(true);

       nRows = 38;
       nCols = 50;

       dash = new BasicStroke(2.0f, CAP_BUTT, JOIN_MITER, 10.0f,
               new float[]{5.0f}, 0.0f);

       addMouseListener(new MouseAdapter() {
           @Override
           public void mousePressed(MouseEvent e) {
               if (gameOver) {
                   startNewGame();
                   repaint();
               }
           }
       });

       addKeyListener(new KeyAdapter() {
           @Override
           public void keyPressed(KeyEvent e) {
               if (gameOver) return;  // disable keystrokes until game starts
               int keyCode = e.getKeyCode();

               if (keyCode == KeyEvent.VK_NUMPAD5) {
                   teleport();

               } else {
                   int k = keyCode - KeyEvent.VK_NUMPAD1;
                   if (k >= 0 && k < 9) {
                       move(k > 4 ? --k : k);
                   }
               }
               repaint();
           }
       });
   }

   void startNewGame() {
       level = 1;
       if (score > hiScore)
           hiScore = score;
       score = 0;
       initGrid();
       gameOver = false;
   }

   void initGrid() {
       grid = new Grid[nRows][nCols];

       teleport();

       int numRobots = 7 * level;
       for (int i = 0; i < numRobots;) {
           int r = rand.nextInt(nRows);
           int c = rand.nextInt(nCols);
           if (grid[r][c] == null) {
               grid[r][c] = Grid.Robot;
               i++;
           }
       }
   }

   boolean movePlayer(int r, int c) {
       if (grid[r][c] != null) {
           gameOver = true;
       } else {
           grid[playerRow][playerCol] = null;
           playerRow = r;
           playerCol = c;
           grid[r][c] = Grid.Player;
       }
       return !gameOver;
   }

   void move(int d) {
       int c = playerCol + dirs[d][0];
       int r = playerRow + dirs[d][1];

       if (!withinBounds(r, c))
           return;

       if (!movePlayer(r, c))
           return;

       for (int rr = 0; rr < nRows; rr++)
           for (int cc = 0; cc < nCols; cc++) {
               if (grid[rr][cc] == Grid.Robot) {

                   // calc new r and c based on dx + cc and dy + rr
                   int nc = (c == cc ? 0 : (c - cc) / abs(c - cc)) + cc;
                   int nr = (r == rr ? 0 : (r - rr) / abs(r - rr)) + rr;

                   if (!withinBounds(nr, nc))
                       continue;

                   grid[rr][cc] = null;

                   if (grid[nr][nc] == Grid.Player) {
                       gameOver = true;
                       return; /* EARLY RETURN */

                   } else if (grid[nr][nc] != null) {
                       score++;
                       if (grid[nr][nc] != Grid.Scrap)
                           score++;
                       grid[nr][nc] = Grid.Scrap;

                   } else {
                       // avoid processing the same robot twice
                       grid[nr][nc] = Grid.Mark;
                   }
               }
           }

       int robotsLeft = 0;
       for (int rr = 0; rr < nRows; rr++)
           for (int cc = 0; cc < nCols; cc++) {
               if (grid[rr][cc] == Grid.Mark)
                   grid[rr][cc] = Grid.Robot;
               if (grid[rr][cc] == Grid.Robot)
                   robotsLeft++;
           }

       if (robotsLeft == 0) {
           level++;
           initGrid();
       }
   }

   void teleport() {
       movePlayer(rand.nextInt(nRows), rand.nextInt(nCols));
   }

   void drawBorder(Graphics2D g) {
       g.setStroke(dash);
       g.setColor(getForeground());
       g.drawRect(22, 20, getWidth() - 41, getHeight() - 72);
   }

   void drawGrid(Graphics2D g) {
       for (int r = 0; r < nRows; r++)
           for (int c = 0; c < nCols; c++) {
               if (grid[r][c] != null)
                   g.drawString(grid[r][c].symbol, 24 + c * 15, 36 + r * 15);
           }
   }

   void drawStartScreen(Graphics2D g) {
       g.setColor(Color.gray);
       g.setFont(new Font("SansSerif", Font.BOLD, 48));
       g.drawString("robots", 315, 280);

       g.setFont(getFont());
       g.drawString("(use numpad to move player)", 270, 350);
       g.drawString("(teleport is numpad 5)", 300, 380);
       g.drawString("(click to start)", 328, 410);
   }

   void drawScore(Graphics2D g) {
       g.setColor(Color.gray);
       g.setFont(getFont());
       String s = format("hiscore   %s    score   %s", hiScore, score);
       g.drawString(s, 30, getHeight() - 17);
   }

   boolean withinBounds(int r, int c) {
       return c >= 0 && c < nCols && r >= 0 && r < nRows;
   }

   @Override
   public void paintComponent(Graphics gg) {
       super.paintComponent(gg);
       Graphics2D g = (Graphics2D) gg;
       g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
               RenderingHints.VALUE_ANTIALIAS_ON);

       drawBorder(g);
       drawScore(g);
       if (gameOver) {
           drawStartScreen(g);
       } else {
           drawGrid(g);
       }
   }

   public static void main(String[] args) {
       SwingUtilities.invokeLater(() -> {
           JFrame f = new JFrame();
           f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           f.setTitle("Robots");
           f.setResizable(false);
           f.add(new Robots(), BorderLayout.CENTER);
           f.pack();
           f.setLocationRelativeTo(null);
           f.setVisible(true);
       });
   }

}</lang>