Parallel Stream Pipeline

spdpiyush · spdpiyush · commit dd418b6af80d · 2025-03-10T14:03:34.000+05:30
diff --git a/Modern-Java-Examples/src/com/learn/parallelstream/ParallelStreamExample1.java b/Modern-Java-Examples/src/com/learn/parallelstream/ParallelStreamExample1.java
@@ -0,0 +1,44 @@
+package com.learn.parallelstream;
+
+import com.learn.data.Student;
+import com.learn.data.StudentDataBase;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ParallelStreamExample1 {
+
+    public static void main(String[] args) {
+        sequentialStudentActivities();
+        parallelStudentActivities();
+    }
+
+    public static List<String> sequentialStudentActivities() {
+        long startTime = System.currentTimeMillis();
+        List<String> studentActivities = StudentDataBase.getAllStudents()
+                .stream() //Stream<Student>
+                .map(Student::getActivities) // Stream<List<String>> -- stateless
+                .flatMap(List::stream) // Stream<String> -- stateless
+                .distinct() // stateful
+                .sorted() //stateful
+                .collect(Collectors.toList());
+        long endTime = System.currentTimeMillis();
+        System.out.println("Sequential Time Take = " +  (endTime - startTime));
+        return studentActivities;
+    }
+
+    public static List<String> parallelStudentActivities() {
+        long startTime = System.currentTimeMillis();
+        List<String> studentActivities = StudentDataBase.getAllStudents()
+                .stream()
+                .parallel()
+                .map(Student::getActivities)
+                .flatMap(List::stream)
+                .distinct()
+                .sorted()
+                .collect(Collectors.toList());
+        long endTime = System.currentTimeMillis();
+        System.out.println("Parallel Time Take = " +  (endTime - startTime));
+        return studentActivities;
+    }
+}
diff --git a/README.md b/README.md
@@ -51,8 +51,9 @@ This repository contains the basic &amp; advance level examples related to Java
     * [ groupingBy()](Modern-Java-Examples/src/com/learn/streams_terminal/StreamsGroupingByExample.java)
     * [ groupingBy() - with maxBy(), minBy() and collectingThen()](Modern-Java-Examples/src/com/learn/streams_terminal/StreamsMinMaxCollectingThenExample.java)
     * [ partitioningBy()](Modern-Java-Examples/src/com/learn/streams_terminal/StreamsPartitioningByExample.java)
-  * [ parallelStream ]
-    * [ parallel Stream Example & Performance](Modern-Java-Examples/src/com/learn/parallelstream/ParallelStreamExample.java)
+  * parallelStream 
+      * [ parallel Stream Example & Performance](Modern-Java-Examples/src/com/learn/parallelstream/ParallelStreamExample.java)
+      * [ sequential & parallel Stream Comparison ](Modern-Java-Examples/src/com/learn/parallelstream/ParallelStreamExample1.java)
 
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