Attempt at movement.

twentyfortyeight/src/twentyfortyeight/Main.java

@@ -81,7 +81,11 @@ class Game extends World {
 
     public void onKeyEvent(String key) {
         System.out.println("YES");
-        if (key == "h") { this.grid.set(0, 0, 8); }
+        if (key.equals("left") || key.equals("h")) this.grid.move(0);
+        else if (key.equals("down") || key.equals("j")) this.grid.move(1);
+        else if (key.equals("up") || key.equals("k")) this.grid.move(2);
+        else if (key.equals("right") || key.equals("l")) this.grid.move(3);
+        else return;
         this.draw();
     }
 
@@ -119,21 +123,45 @@ class Grid {
         return free;
     }
 
-    // Set the tile at the coords. Just for testing.
+    // Get the indexes of all "unfree" cells -- those whose value in buf is not
+    // 0, and represent a used tile.
+    List<Integer> unfreeCellIdxs() {
+        List<Integer> unfree = new ArrayList<>();
+        for (int i = 0; i < this.sz; i++)
+            if (this.buf.get(i) != 0 && unfree.add(i)) continue;
+
+        return unfree;
+    }
+
+    // Set the tile at the coords.
     Grid set(int x, int y, int v) {
         this.buf.set(this.w * y + x, v);
         return this;
     }
 
-    // Get the value at the coords. Just for testing.
+    // Get the value at the coords.
     int get(int x, int y) { return this.buf.get(this.w * y + x); }
 
+    // Get the x coord for an index.
+    int ix(int i) { return i % this.h; }
+
+    // Get the y coord for an index.
+    int iy(int i) { return i % this.w; }
+
     // Move all tiles in that direction until they can't move or combine any
     // more.
     void move(int d) {
         // TODO: Don't assume right.
         // Assume right.
-        for (int i = 0; i < this.h; i++) {}
+        List<Integer> unfrees = this.unfreeCellIdxs();
+        List<Integer> frees = this.freeCellIdxs();
+        for (int unfree : unfrees) {
+            /*
+            if (frees.contains(this.ix(unfree) + 1)) {
+                this.buf.set(unfree, 0))
+            }
+            */
+        }
     }
 
     // Render the grid.
@@ -204,7 +232,7 @@ class Examples {
     }
 
     /*
-    void testMoveLeft(Tester t) {
+    void testMoveRight(Tester t) {
         init();
         regular.set(1, 0, 16)
             .set(2, 0, 16)