Add all 23 GoF design pattern implementations (2026-06-13)

02-structural/flyweight/TreeFactory.java

@@ -0,0 +1,29 @@
+package flyweight;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Flyweight Factory — the cache that ensures each unique TreeType
+ * is only created once, no matter how many trees use it.
+ *
+ * This is the piece that makes Flyweight work:
+ * it intercepts creation requests and returns an existing
+ * shared instance if one already exists.
+ */
+public class TreeFactory {
+
+    // The pool of shared flyweights
+    private static final Map<String, TreeType> treeTypes = new HashMap<>();
+
+    public static TreeType getTreeType(String name, String color, String texture) {
+        String key = name + "_" + color + "_" + texture;
+
+        // Only create a new TreeType if we haven't seen this combination before
+        return treeTypes.computeIfAbsent(key, k -> new TreeType(name, color, texture));
+    }
+
+    public static int getPoolSize() {
+        return treeTypes.size();
+    }
+}