For Review

README.md

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+## Mine Sweeper
+
+For this recipe, you will be implementing a simplified version of the
+[Mine Sweeper](https://en.wikipedia.org/wiki/Minesweeper_(video_game)) game.
+
+The purpose of this exercise is to introduce you to *functional programming*
+aspects of Java introduced in Java 8. Specifically, it will cover:
+
+- [Lambda Expressions](https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html)
+- [Method References](https://docs.oracle.com/javase/tutorial/java/javaOO/methodreferences.html)
+
+To complete the recipe, please follow all the instructions laid out in
+MineSweeper.java.

src/org/jointheleague/level4/minesweeper/MineSweeper.java

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+package org.jointheleague.level4.minesweeper;
+
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.GridLayout;
+import java.util.Optional;
+import java.util.Random;
+import java.util.stream.IntStream;
+
+import javax.swing.JButton;
+import javax.swing.JFrame;
+import javax.swing.JMenu;
+import javax.swing.JMenuBar;
+import javax.swing.JMenuItem;
+import javax.swing.JPanel;
+import javax.swing.SwingUtilities;
+import javax.swing.WindowConstants;
+
+/**
+ * Implement the Mine Sweeper game by following the instructions in the
+ * comments. All instructions are marked with "TODO".
+ */
+public class MineSweeper {
+    private static final int WIDTH = 10;
+    private static final int HEIGHT = 15;
+    private static final int CELL_SIZE = 20;
+    private static final int NUM_MINES = 15;
+
+    final JFrame frame = new JFrame();
+    private final JButton[][] buttons = new JButton[HEIGHT][WIDTH];
+    private final Random rng = new Random();
+    private Optional<boolean[][]> mines = Optional.empty();
+    private int numCellsRemaining;
+
+    /**
+     * Initializes:
+     * 1. The `mines` variable with `NUM_MINES` randomly distributed mines
+     * 2. The `numCellsRemaining` variable to the number of non-mine
+     *    cells (`WIDTH` * `HEIGHT` - `NUM_MINES`).
+     * 
+     * @param firstCellX X-index of first cell opened. This cannot be a mine.
+     * @param firstCellY Y-index of first cell opened. This cannot be a mine.
+     */
+    private void initializeMines(int firstCellX, int firstCellY) {
+        // TODO fill in
+        // Hint, use `Optional.of(...)` to create a non-empty `Optional`.
+    }
+
+    /**
+     * Inspects a given cell, and count the number of neighboring cells that
+     * are mines.
+     * 
+     * @param x X-index of cell to inspect.
+     * @param y Y-index of cell to inspect.
+     * @return The number of neighboring cells that are mines (0-8).
+     */
+    private Integer getNeighboringMinesCount(int x, int y) {
+        // TODO fill in
+        return null;
+    }
+
+    /**
+     * Resets the game by:
+     * 1. Setting the `mines` variable back to empty.
+     * 2. Clearing the button texts, and setting button states to enabled.
+     * 
+     * @param unused Just here so that method can be passed as ActionListener.
+     */
+    private void resetGame(Object unused) {
+        // TODO fill in
+    }
+
+    private void createAndShowFrame() {
+        final JMenuItem resetMenuItem = new JMenuItem("Reset");
+        resetMenuItem.addActionListener(null); // TODO replace null with method reference that resets the game
+
+        final JMenu gameMenu = new JMenu("Game");
+        gameMenu.add(resetMenuItem);
+
+        final JMenuBar menuBar = new JMenuBar();
+        menuBar.add(gameMenu);
+
+        final JPanel controlPanel = new JPanel();
+        final JButton resetButton = new JButton("Reset");
+        resetButton.addActionListener(null); // TODO replace null with method reference that resets the game
+        controlPanel.add(resetButton);
+
+        final JPanel gameBoardPanel = new JPanel();
+        gameBoardPanel.setSize(WIDTH * CELL_SIZE, HEIGHT * CELL_SIZE);
+        gameBoardPanel.setBackground(Color.WHITE);
+        gameBoardPanel.setLayout(new GridLayout(HEIGHT, WIDTH));
+        IntStream.range(0, HEIGHT).forEach(y ->
+            IntStream.range(0, WIDTH).forEach(x -> {
+                // This code loops through the X and Y indexes,
+                // creating a button for each cell.
+                final JButton b = new JButton();
+                buttons[y][x] = b;
+                // When the cell button is pressed, it should:
+                // 1. Initializes the mines if it is not yet initialized.
+                // 2. If the button is a mine:
+                //    - Change the button text to an "X"
+                //    - Display "You Lose" in a dialog box
+                //    Otherwise:
+                //    - Change the button text to the number of neighboring
+                //      cells are mines.
+                //    - Decrement `numCellsRemaining`
+                //    - If all cells are open, display "You Win" in a dialog box
+                //    - Extra credit: If the number of neighboring cells is 0,
+                //      automatically open all neighboring cells
+                b.addActionListener(null); // TODO replace null with lambda expression
+                gameBoardPanel.add(b);
+            })
+        );
+
+        final JFrame frame = new JFrame();
+        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
+        frame.setSize(WIDTH * CELL_SIZE, (HEIGHT + 1) * CELL_SIZE + 27);
+        frame.setLayout(new BorderLayout());
+        frame.setResizable(false);
+        frame.setJMenuBar(menuBar);
+        frame.add(gameBoardPanel, BorderLayout.CENTER);
+        frame.add(controlPanel, BorderLayout.PAGE_END);
+
+        frame.setVisible(true);
+    }
+
+    public static void main(String[] args) {
+        System.setProperty("apple.laf.useScreenMenuBar", "true");
+        final MineSweeper mineSweeper = new MineSweeper();
+        SwingUtilities.invokeLater(mineSweeper::createAndShowFrame);
+    }
+}