diff --git a/java-concurrent-hm-compute-if-absent/README.MD b/java-concurrent-hm-compute-if-absent/README.MD
new file mode 100644
index 0000000..e69de29
diff --git a/java-concurrent-hm-compute-if-absent/pom.xml b/java-concurrent-hm-compute-if-absent/pom.xml
new file mode 100644
index 0000000..18d1b01
--- /dev/null
+++ b/java-concurrent-hm-compute-if-absent/pom.xml
@@ -0,0 +1,22 @@
+
+ 4.0.0
+
+ com.pivovarit
+ 1.0
+ java-concurrent-hm-compute-if-absent
+
+ java-concurrent-hm-compute-if-absent
+
+
+
+ org.apache.maven.plugins
+ maven-compiler-plugin
+
+
+ 21
+
+
+
+
+
diff --git a/java-concurrent-hm-compute-if-absent/src/main/java/com/pivovarit/chm/ComputeIfAbsentExample.java b/java-concurrent-hm-compute-if-absent/src/main/java/com/pivovarit/chm/ComputeIfAbsentExample.java
new file mode 100644
index 0000000..85ea3aa
--- /dev/null
+++ b/java-concurrent-hm-compute-if-absent/src/main/java/com/pivovarit/chm/ComputeIfAbsentExample.java
@@ -0,0 +1,35 @@
+package com.pivovarit.chm;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Stream;
+
+class ComputeIfAbsentExample {
+
+ public static void main(String[] args) {
+ var map = new ConcurrentHashMap<>(1024);
+ var counter = new AtomicInteger();
+ Stream.of(1, 2)
+ .map(tid -> Thread.ofPlatform().start(() -> {
+ for (int i = 0; i < 10; i++) {
+ int key = ThreadLocalRandom.current().nextInt(10);
+ map.computeIfAbsent(key, s -> {
+ if (counter.incrementAndGet() > 1) {
+ System.out.println("I told you so!");
+ }
+ doWork();
+ counter.decrementAndGet();
+ return key;
+ });
+ }
+ })).forEach(t -> {});
+ }
+
+ private static void doWork() {
+ try {
+ Thread.sleep(100);
+ } catch (InterruptedException ignored) {
+ }
+ }
+}
diff --git a/pom.xml b/pom.xml
index 6a1d53d..1988de2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -24,6 +24,7 @@
java-archunit
java-sealed-classes
java-completable-future-timeouts
+ java-concurrent-hm-compute-if-absent
java-event-sourcing
java-completable-future-allof
java-advanced-groupingby