Update README.md

alpha74 · web-flow · commit 075dca3733ea · 2024-08-29T17:30:17.000+05:30
diff --git a/README.md b/README.md
@@ -87,7 +87,25 @@ List<String> vehicleLenList = vehicles.stream()
         .collect(Collectors.toList());
 ```
 
+-------
+
+#### flatMap()
+
+- Given a collection of objects, `map()` takes one input and returns one output, whereas `flatMap()` takes one input, but returns a stream of objects.
+
+- Example to combine a list of list of objects into single list using `flatMap()`
 
+```
+List<Integer> list1 = Arrays.asList(1,2);
+List<Integer> list2 = Arrays.asList(3,4);
+List<Integer> list3 = Arrays.asList(5,6);
+
+List<List<Integer>> listList = Arrays.asList(list1, list2, list3);
 
+// Combine all lists into single list
+List<Integer> combinedList = listList.stream().flatMap(x -> x.stream()).collect(Collectors.toList());
+
+// Output: [1,2,3,4,5,6]
+```
 
 
