From 82500be545723688d609824cbfbfac006e8a8f31 Mon Sep 17 00:00:00 2001
From: Bahaa El-Din Helmy <bahaavampire@yahoo.com>
Date: Wed, 24 May 2023 17:59:59 +0300
Subject: [PATCH] Array vs List Performance in Java (#14114)

This commit is related to the article entitled "Array vs List Performance in Java"
---
 .../ArrayAndArrayListPerformance.java         | 116 ++++++++++--------
 1 file changed, 64 insertions(+), 52 deletions(-)

diff --git a/core-java-modules/core-java-collections-list-5/src/main/java/com/baeldung/arrayandlistperformance/ArrayAndArrayListPerformance.java b/core-java-modules/core-java-collections-list-5/src/main/java/com/baeldung/arrayandlistperformance/ArrayAndArrayListPerformance.java
index 3b8fa8c9f3..59540c69b9 100644
--- a/core-java-modules/core-java-collections-list-5/src/main/java/com/baeldung/arrayandlistperformance/ArrayAndArrayListPerformance.java
+++ b/core-java-modules/core-java-collections-list-5/src/main/java/com/baeldung/arrayandlistperformance/ArrayAndArrayListPerformance.java
@@ -1,65 +1,77 @@
 package com.baeldung.arrayandlistperformance;
+
 import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
 import org.openjdk.jmh.runner.options.OptionsBuilder;
+
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.concurrent.TimeUnit;
+
 @State(Scope.Benchmark)
 @BenchmarkMode(Mode.AverageTime)
 @OutputTimeUnit(TimeUnit.NANOSECONDS)
 public class ArrayAndArrayListPerformance {
 
-    @Benchmark
-    public void arrayCreation() {
-        int[] array = new int[1000000];
-    }
-
-    @Benchmark
-    public void arrayListCreation() {
-        ArrayList<Integer> list = new ArrayList<>(1000000);
-    }
-
-    @Benchmark
-    public void arrayItemSetting() {
-        int[] array = new int[1000000];
-        array[0] = 10;
-    }
-
-    @Benchmark
-    public void arrayListItemSetting() {
-        ArrayList<Integer> list = new ArrayList<>(1000000);
-        list.add(0, 10);
-    }
-
-    @Benchmark
-    public void arrayItemRetrieval() {
-        int[] array = new int[1000000];
-        array[0] = 10;
-        int item = array[0];
-    }
-
-    @Benchmark
-    public void arrayListItemRetrieval() {
-        ArrayList<Integer> list = new ArrayList<>(1000000);
-        list.add(0, 10);
-        int item2 = list.get(0);
-    }
-
-    @Benchmark
-    public void arrayCloning() {
-        int[] array = new int[1000000];
-        int[] newArray = array.clone();
-    }
-
-    @Benchmark
-    public void arrayListCloning() {
-        ArrayList<Integer> list = new ArrayList<>(1000000);
-        ArrayList<Integer> newList = new ArrayList<>(list);
-    }
     public static void main(String[] args) throws Exception {
-        org.openjdk.jmh.runner.Runner runner = new org.openjdk.jmh.runner.Runner(new OptionsBuilder()
-                .include(ArrayAndArrayListPerformance.class.getSimpleName())
-                .forks(1)
-                .build());
+        org.openjdk.jmh.runner.Runner runner = new org.openjdk.jmh.runner.Runner(new OptionsBuilder().include(ArrayAndArrayListPerformance.class.getSimpleName()).forks(1).build());
         runner.run();
     }
-    }
\ No newline at end of file
+    public static Integer[] array = Collections.nCopies(256, 1).toArray(new Integer[0]);
+    public static ArrayList<Integer> list = new ArrayList<Integer>(
+            Arrays.asList(array));
+    @Benchmark
+    public Integer[] arrayCreation() {
+        return new Integer[256];
+    }
+
+    @Benchmark
+    public ArrayList<Integer> arrayListCreation() {
+        return new ArrayList<>(256);
+    }
+
+    @Benchmark
+    public Integer[] arrayItemsSetting() {
+        for (int i = 0; i < 256; i++) {
+            array[i] = i;
+        }
+        return array;
+    }
+
+    @Benchmark
+    public ArrayList<Integer> arrayListItemsSetting() {
+        for (int i = 0; i < 256; i++) {
+            list.set(i,i);
+        }
+        return list;
+    }
+
+    @Benchmark
+    public void arrayItemsRetrieval(Blackhole blackhole) {
+        for (int i = 0; i < 256; i++) {
+            int item = array[i];
+            blackhole.consume(item);
+        }
+    }
+
+    @Benchmark
+    public void arrayListItemsRetrieval(Blackhole blackhole) {
+        for (int i = 0; i < 256; i++) {
+            int item = list.get(i);
+            blackhole.consume(item);
+        }
+    }
+
+    @Benchmark
+    public void arrayCloning(Blackhole blackhole) {
+        Integer[] newArray = array.clone();
+        blackhole.consume(newArray);
+    }
+
+    @Benchmark
+    public void arrayListCloning(Blackhole blackhole) {
+        ArrayList<Integer> newList = new ArrayList<>(list);
+        blackhole.consume(newList);
+    }
+}
\ No newline at end of file