Refine the directory.

Author: ZahidFKhan

src/test/java/com/github/streams/learn/a_basics/intermediate_operations/A_Filter.md

@@ -0,0 +1,16 @@
+# Filter:
+
+The `filter` is an intermediate operation used to select elements from a stream based on a condition. Only the elements that satisfy the predicate (return true) are kept, and the rest are removed.
+
+Example
+```java
+List<Integer> result = List.of(1, 2, 3, 4, 5).stream()
+.filter(n -> n % 2 == 0)
+.toList();
+
+System.out.println(result);
+```
+Output
+```java
+[2, 4]
+```

src/test/java/com/github/streams/learn/a_basics/intermediate_operations/B_Map.md

@@ -0,0 +1,19 @@
+# Map:
+
+Map is an intermediate operation used to transform each element of a stream into another value.
+It applies a function to every element and produces a new stream containing the transformed elements.
+
+Example
+```java
+List<Integer> result = List.of(1, 2, 3, 4).stream()
+.map(n -> n * 2)
+.toList();
+
+System.out.println(result);
+```
+
+
+Output
+```java
+[2, 4, 6, 8]
+```