From 6079210fba625af6a913569fb81f1a841661e2a8 Mon Sep 17 00:00:00 2001
From: Colin DAMON <cdamon@ippon.fr>
Date: Tue, 20 Apr 2021 13:18:28 +0200
Subject: [PATCH] Java puzzles subject
---
.gitlab-ci.yml | 1 +
java-puzzles/.gitlab-ci.yml | 11 ++
java-puzzles/pom.xml | 25 ++++
java-puzzles/readme.md | 9 ++
.../java/fr/ippon/PlayingWithBigDecimal.java | 18 +++
.../java/fr/ippon/PlayingWithFinally.java | 40 +++++++
.../fr/ippon/PlayingWithInstanciations.java | 27 +++++
.../java/fr/ippon/PlayingWithInteger.java | 31 +++++
.../test/java/fr/ippon/PlayingWithString.java | 28 +++++
.../java/fr/ippon/PlayingWithThreads.java | 113 ++++++++++++++++++
readme.md | 1 +
11 files changed, 304 insertions(+)
create mode 100644 java-puzzles/.gitlab-ci.yml
create mode 100644 java-puzzles/pom.xml
create mode 100644 java-puzzles/readme.md
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithBigDecimal.java
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithFinally.java
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithInstanciations.java
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithInteger.java
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithString.java
create mode 100644 java-puzzles/src/test/java/fr/ippon/PlayingWithThreads.java
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c46551df..a3769253 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -35,3 +35,4 @@ include:
- local: "/tennis/greenfield-2/.gitlab-ci.yml"
- local: "/mastermind/.gitlab-ci.yml"
- local: "/try-monade/.gitlab-ci.yml"
+ - local: "/java-puzzles/.gitlab-ci.yml"
diff --git a/java-puzzles/.gitlab-ci.yml b/java-puzzles/.gitlab-ci.yml
new file mode 100644
index 00000000..a140bf09
--- /dev/null
+++ b/java-puzzles/.gitlab-ci.yml
@@ -0,0 +1,11 @@
+package-java-puzzles:
+ variables:
+ PROJECT_FOLDER: "java-puzzles"
+ extends: .java
+ only:
+ refs:
+ - master
+ - merge_requests
+ changes:
+ - ".gitlab-common-ci.yml"
+ - "java-puzzles/**/*"
diff --git a/java-puzzles/pom.xml b/java-puzzles/pom.xml
new file mode 100644
index 00000000..78810fa2
--- /dev/null
+++ b/java-puzzles/pom.xml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <parent>
+ <version>1.0.0</version>
+ <groupId>fr.ippon.kata</groupId>
+ <artifactId>java-parent</artifactId>
+ <relativePath>../java-parent</relativePath>
+ </parent>
+
+ <version>1.0.0-SNAPSHOT</version>
+ <artifactId>java-puzzles</artifactId>
+
+ <name>JavaPuzzles</name>
+
+ <developers>
+ <developer>
+ <email>cdamon@ippon.fr</email>
+ <name>Colin DAMON</name>
+ </developer>
+ </developers>
+</project>
diff --git a/java-puzzles/readme.md b/java-puzzles/readme.md
new file mode 100644
index 00000000..deb2fb5f
--- /dev/null
+++ b/java-puzzles/readme.md
@@ -0,0 +1,9 @@
+# Java puzzles
+
+Petits exercices de code Java
+
+- **Auteurs** : Colin DAMON
+- **Date** : 22/04/2021
+- **Langage** : Java
+- **Niveau** : TODO
+- **Replay** : TODO
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithBigDecimal.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithBigDecimal.java
new file mode 100644
index 00000000..bb76436c
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithBigDecimal.java
@@ -0,0 +1,18 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.math.BigDecimal;
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithBigDecimal {
+
+ @Test
+ public void roundingSubstract() {
+ BigDecimal a = new BigDecimal(2.00);
+ BigDecimal b = new BigDecimal(0.99);
+ // assertThat(a.subtract(b).toString()).isEqualTo("1");
+ // assertThat(a.subtract(b).toString()).isEqualTo("1.01");
+ // assertThat(a.subtract(b).toString()).isEqualTo("1.0100000000000000088817841970012523233890533447265625");
+ }
+}
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithFinally.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithFinally.java
new file mode 100644
index 00000000..2e62acf4
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithFinally.java
@@ -0,0 +1,40 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithFinally {
+
+ @Test
+ public void playingWithReturn() {
+ // assertThat(finallyReturn()).isEqualTo(42);
+ // assertThat(finallyReturn()).isEqualTo(1337);
+ }
+
+ @SuppressWarnings("finally")
+ private int finallyReturn() {
+ try {
+ return 42;
+ } finally {
+ return 1337;
+ }
+ }
+
+ @Test
+ public void playingWithThrow() {
+ // assertThat(finallyThrow()).isEqualTo(42);
+ // assertThatThrownBy(() -> finallyThrow())
+ // .isInstanceOf(IllegalArgumentException.class)
+ // .hasMessageContaining("Damned");
+ }
+
+ @SuppressWarnings("finally")
+ private int finallyThrow() {
+ try {
+ return 42;
+ } finally {
+ throw new IllegalArgumentException("Damned");
+ }
+ }
+}
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithInstanciations.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithInstanciations.java
new file mode 100644
index 00000000..34c32f54
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithInstanciations.java
@@ -0,0 +1,27 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithInstanciations {
+ private static final long instanciation = System.currentTimeMillis();
+
+ @Test
+ public void playingWithInstanciationTime() throws InterruptedException {
+ Thread.sleep(10);
+ long start = System.currentTimeMillis();
+
+ // assertThat(start).isLessThanOrEqualTo(instanciation);
+ // assertThat(start).isGreaterThan(instanciation);
+ MyPrivateClass.doStuff();
+ // assertThat(start).isLessThanOrEqualTo(MyPrivateClass.instanciation);
+ // assertThat(start).isGreaterThan(MyPrivateClass.instanciation);
+ }
+
+ private static class MyPrivateClass {
+ private static final long instanciation = System.currentTimeMillis();
+
+ private static void doStuff() {}
+ }
+}
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithInteger.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithInteger.java
new file mode 100644
index 00000000..547c5670
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithInteger.java
@@ -0,0 +1,31 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithInteger {
+
+ @Test
+ public void comparingUniversaleAnswerIntegerReferences() {
+ Integer a = 42;
+ Integer b = 42;
+ // assertThat(a).isSameAs(b);
+ // assertThat(a).isNotSameAs(b);
+ }
+
+ @Test
+ public void comparingDevilIntegerReferences() {
+ Integer a = 666;
+ Integer b = 666;
+ // assertThat(a).isSameAs(b);
+ // assertThat(a).isNotSameAs(b);
+ }
+
+ @Test
+ public void checkingAbsoluteValue() {
+ // assertThat(Math.abs(Integer.MIN_VALUE)).isEqualTo(Integer.MAX_VALUE);
+ // assertThat(Math.abs(Integer.MIN_VALUE))
+ // .isEqualTo(Integer.MIN_VALUE);
+ }
+}
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithString.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithString.java
new file mode 100644
index 00000000..1210d5b9
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithString.java
@@ -0,0 +1,28 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithString {
+
+ @Test
+ public void playingWithReferences() {
+ // assertThat("coucou").isSameAs("coucou");
+ // assertThat("coucou").isNotSameAs("coucou");
+ }
+
+ @Test
+ public void playingWithStringObjectsReferences() {
+ // assertThat(new String("coucou")).isSameAs(new String("coucou"));
+ // assertThat(new String("coucou")).isNotSameAs(new String("coucou"));
+ }
+
+ @Test
+ public void playingWithIntern() {
+ // assertThat(new String("coucou").intern())
+ // .isSameAs(new String("coucou").intern());
+ // assertThat(new String("coucou").intern()).isNotSameAs(new
+ // String("coucou").intern());
+ }
+}
diff --git a/java-puzzles/src/test/java/fr/ippon/PlayingWithThreads.java b/java-puzzles/src/test/java/fr/ippon/PlayingWithThreads.java
new file mode 100644
index 00000000..559432d2
--- /dev/null
+++ b/java-puzzles/src/test/java/fr/ippon/PlayingWithThreads.java
@@ -0,0 +1,113 @@
+package fr.ippon;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Collections;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.junit.jupiter.api.Test;
+
+public class PlayingWithThreads {
+ private static boolean threadDoneFlag;
+
+ private static AtomicBoolean threadDoneAtomicFlag = new AtomicBoolean(false);
+
+ @Test
+ public void playingWithSimpleDateFormat() throws InterruptedException {
+ Set<Integer> days = Collections.newSetFromMap(new ConcurrentHashMap<>());
+ ExecutorService executor = Executors.newFixedThreadPool(10);
+
+ AtomicInteger counter = new AtomicInteger(1);
+ for (int i = 1; i < 32; ++i) {
+ executor.submit(
+ () -> {
+ SimpleDateFormat format = new SimpleDateFormat("dd");
+ Date date = new GregorianCalendar(2018, Calendar.JANUARY, counter.getAndIncrement()).getTime();
+ days.add(Integer.parseInt(format.format(date)));
+ }
+ );
+ }
+
+ executor.shutdown();
+ executor.awaitTermination(3, TimeUnit.SECONDS);
+ // assertThat(days).hasSize(31);
+ // assertThat(days.size()).isLessThan(31);
+ }
+
+ @Test
+ public void firstAttemptToStopAThread() throws InterruptedException {
+ AtomicBoolean threadStopped = new AtomicBoolean();
+
+ new Thread(
+ () -> {
+ while (!threadDoneFlag) {}
+
+ threadStopped.set(true);
+ }
+ )
+ .start();
+
+ Thread.sleep(500);
+
+ threadDoneFlag = true;
+
+ Thread.sleep(50);
+ // assertThat(threadStopped.get()).isFalse();
+ // assertThat(threadStopped.get()).isTrue();
+ }
+
+ @Test
+ public void secondAttemptToStopAThread() throws InterruptedException {
+ AtomicBoolean threadStopped = new AtomicBoolean();
+
+ new Thread(
+ () -> {
+ while (!threadDoneFlag) {
+ System.out.println(threadDoneFlag); // Ok, let's just log the flag
+ }
+
+ threadStopped.set(true);
+ }
+ )
+ .start();
+
+ Thread.sleep(500);
+
+ threadDoneFlag = true;
+
+ Thread.sleep(50);
+ // assertThat(threadStopped.get()).isFalse();
+ // assertThat(threadStopped.get()).isTrue();
+ }
+
+ @Test
+ public void thirdAttemptToStopAThread() throws InterruptedException {
+ AtomicBoolean threadStopped = new AtomicBoolean();
+
+ new Thread(
+ () -> {
+ while (!threadDoneAtomicFlag.get()) {}
+
+ threadStopped.set(true);
+ }
+ )
+ .start();
+
+ Thread.sleep(500);
+
+ threadDoneAtomicFlag.set(true);
+
+ Thread.sleep(50);
+ // assertThat(threadStopped.get()).isFalse();
+ // assertThat(threadStopped.get()).isTrue();
+ }
+}
diff --git a/readme.md b/readme.md
index 05d94138..d83bded7 100644
--- a/readme.md
+++ b/readme.md
@@ -43,6 +43,7 @@ Un kata de code est un petit exercice pensé pour s'entrainer jusqu'à maitriser
- [Movie rental](/movie-rental)
- [Bowling Game](/bowling-game)
- [Tennis Refactoring kata](/tennis/refactoring)
+- [Puzzles](java-puzzles)
### Énervé
--
GitLab