2 files changed, 67 insertions, 15 deletions

diff --git a/src/main/java/fr/umlv/java/wallj/board/Board.java b/src/main/java/fr/umlv/java/wallj/board/Board.java
index ebe1a7e..dfcec88 100644
--- a/src/main/java/fr/umlv/java/wallj/board/Board.java
+++ b/src/main/java/fr/umlv/java/wallj/board/Board.java
@@ -1,16 +1,51 @@
 package fr.umlv.java.wallj.board;

 

 import fr.umlv.java.wallj.model.BlockType;

+import fr.umlv.java.wallj.utils.Matrix;

 

 /**

- * A mutable BlockType matrix.

+ * An immutable BlockType matrix.

  */

 public final class Board {

 

+  /**

+   * Board Builder

+   */

+  public static final class Builder {

+    private final BlockType[][] map;

+

+    /**

+     * @param width  width in tiles

+     * @param height height in tiles

+     */

+    public Builder(int width, int height) {

+      this.map = new BlockType[width][height];

+    }

+

+    /**

+     * @param pos  the tile position vector

+     * @param type the BlockType to set

+     * @return the Builder

+     */

+    public Builder setBlockTypeAt(TileVec2 pos, BlockType type) {

+      map[pos.getCol()][pos.getRow()] = type;

+      return this;

+    }

+

+    /**

+     * @return the immutable Board

+     */

+    public Board build() {

+      return new Board(map);

+    }

+  }

+

   private final BlockType[][] map;

 

-  public Board(int width, int height) {

-    map = new BlockType[width][height];

+  private Board(BlockType[][] map) {

+    int w = Matrix.getWidth(map), h = Matrix.getHeight(map);

+    this.map = new BlockType[w][h];

+    for (int row = 0; row < w; ++row) System.arraycopy(map[row], 0, this.map[row], 0, h);

   }

 

   /**

@@ -22,21 +57,10 @@ public final class Board {
   }

 

   /**

-   * @param pos  the tile position vector

-   * @param type the BlockType to set

-   * @return the overwritten element

-   */

-  public BlockType setBlockTypeAt(TileVec2 pos, BlockType type) {

-    BlockType old = map[pos.getCol()][pos.getRow()];

-    map[pos.getCol()][pos.getRow()] = type;

-    return old;

-  }

-

-  /**

    * @return the dimension of the Board

    */

   public TileVec2 getDim() {

-    return TileVec2.of(map.length, map.length > 0 ? map[0].length : 0);

+    return TileVec2.of(Matrix.getWidth(map), Matrix.getHeight(map));

   }

 

 }

diff --git a/src/main/java/fr/umlv/java/wallj/utils/Matrix.java b/src/main/java/fr/umlv/java/wallj/utils/Matrix.java
new file mode 100644
index 0000000..e23cb2a
--- /dev/null
+++ b/src/main/java/fr/umlv/java/wallj/utils/Matrix.java
@@ -0,0 +1,28 @@
+package fr.umlv.java.wallj.utils;
+
+/**
+ * Utility functions for two dimension arrays.
+ */
+public final class Matrix {
+
+  /**
+   * @param m the matrix
+   * @return the width of the matrix (0 if null)
+   */
+  public static int getWidth(Object[][] m) {
+    return m != null && m.length > 0 ? m[0].length : 0;
+  }
+
+  /**
+   * @param m the matrix
+   * @return the height of the matrix (0 if null)
+   */
+  public static int getHeight(Object[][] m) {
+    return m != null ? m.length : 0;
+  }
+
+  private Matrix() {
+    // static class
+  }
+
+}