In September 2017 the long-awaited release of Java 9 gave us a new module system in Java. It also kick-started the release-train of frequent Java releases, with Java 11 being the first long-term supported Java version poised to take modules into the mainstream. So what has happened since the introduction of the module system? This talk will provide an overview adoption of modules in open-source libraries, IDEs, build tools, and so on. It will also feature tools that have emerged to make working with modules easier. Expect an honest overview of the current state of modules in Java, with lots of demos to show what's possible. After this talk you can start developing your own modular Java application without hesitation!

1. By Sander Mak
Java Modularity:
@Sander_Mak
The Year After

2. About Sander
Fellow, Software Architect
@ Luminis
Experience in modular
development stacks
Conference Speaker & Author

3. @Sander_Mak
Quick Java Module Refresher

4. @Sander_Mak
module main {
}
module-info.java
Module Descriptors

5. @Sander_Mak
module main {
}
module-info.java
Module Descriptors
main.web
main.persistence
main.integration
main

6. @Sander_Mak
module main {
requires helper;
}
module-info.java
module helper {
}
module-info.java
Explicit Dependencies
main.web
main.persistence
main.integration
main

7. @Sander_Mak
module main {
requires helper;
}
module-info.java
module helper {
}
module-info.java
helper
Explicit Dependencies
main.web
main.persistence
main.integration
main

8. @Sander_Mak
module main {
requires helper;
}
module helper {
exports helper.api;
}
module-info.java module-info.java
helper.api
helper
Well-defined Interfaces
main.web
main.persistence
main.integration
main

9. @Sander_Mak
module main {
requires helper;
}
module helper {
exports helper.api;
}
module-info.java module-info.java
helper.api
helper.impl
helper
Strong Encapsulation
main.web
main.persistence
main.integration
main

10. @Sander_Mak
Improvements Since Java 9

11. @Sander_Mak
Improvements Since Java 9

12. @Sander_Mak
Why?

13. @Sander_Mak
Why?
Modular JDK

14. @Sander_Mak
Why?
Modular JDK
Maintainability
Reliable composition
Flexibility

15. @Sander_Mak
Why?
Modular JDK
Maintainability
Reliable composition
jlink
main
lib1 lib2
java.base
java.logging
java.xml
Custom Run-time Image
Flexibility

16. @Sander_Mak
quick refresher
why/advantages
(JDK: modularized, your app: architecture from whiteboard to code, explicit dependencies in language, strong encapsulation, jlink
Why?
Decrease the model-code gap

17. @Sander_Mak
Let's Talk About Adoption

18. @Sander_Mak
Let's Talk About Adoption

19. @Sander_Mak
Let's Talk About Adoption
TEH
CODEZ

20. @Sander_Mak
https://jaxenter.com/java-8-still-strong-java-10-142642.html

21. @Sander_Mak
https://jaxenter.com/java-8-still-strong-java-10-142642.html
https://www.baeldung.com/java-in-2018

22. @Sander_Mak
https://jaxenter.com/java-8-still-strong-java-10-142642.html
https://www.baeldung.com/java-in-2018
https://www.jetbrains.com/research/devecosystem-2018/java/

23. @Sander_Mak
https://jaxenter.com/java-8-still-strong-java-10-142642.html
https://www.baeldung.com/java-in-2018
https://www.jetbrains.com/research/devecosystem-2018/java/
Java Magazine & Snyk

24. @Sander_Mak
https://jaxenter.com/java-8-still-strong-java-10-142642.html
https://www.baeldung.com/java-in-2018
https://www.jetbrains.com/research/devecosystem-2018/java/
Java Magazine & Snyk

25. @Sander_Mak
Java 11

26. @Sander_Mak
Java 11
Java 9
Java 10
Java 12
Java 13
6 months
Java 11

27. @Sander_Mak
Java 11
Java 9
Java 10
Java 12
Java 13
6 months
Java 11

28. @Sander_Mak
Java 11
Long
Term
Support
Java 9
Java 10
Java 12
Java 13
6 months
Java 11 Java 11 LTS
minimum 3 years

29. @Sander_Mak
What About the
Java Module System
?

30. @Sander_Mak
What About the
Java Module System
?
JCP Survey: https://www.surveymonkey.com/results/SM-YR7YQJJJL/

31. @Sander_Mak
Java 8 Lambdas &
Streams

32. @Sander_Mak
Java 8 Lambdas &
Streams
Java 9
Modularity

33. @Sander_Mak
Let's Talk About Libraries

34. @Sander_Mak
https://wiki.openjdk.java.net/display/quality/Quality+Outreach
OpenJDK Quality Outreach

35. @Sander_Mak
https://wiki.openjdk.java.net/display/quality/Quality+Outreach
OpenJDK Quality Outreach
Log4J, Jetty, Hibernate, Javassist, Mockito, RxJava, Spring, ...

36. @Sander_Mak
https://wiki.openjdk.java.net/display/quality/Quality+Outreach
OpenJDK Quality Outreach
Log4J, Jetty, Hibernate, Javassist, Mockito, RxJava, Spring, ...
60% Java 10 compatible

37. @Sander_Mak
Modular Libraries: Modularization Levels

38. @Sander_Mak
Modular Libraries: Modularization Levels
Level 0: ¯_(ツ)_/¯

39. @Sander_Mak
Modular Libraries: Modularization Levels
Level 0: ¯_(ツ)_/¯
Level 1: Automatic-Module-Name

40. @Sander_Mak
Modular Libraries: Modularization Levels
Level 0: ¯_(ツ)_/¯
Level 1: Automatic-Module-Name
Level 2: Publish modularized JAR

41. @Sander_Mak
Modular Libraries

42. @Sander_Mak
Modular Libraries
AdoptOpenJDK
ModuleScanner
+

43. @Sander_Mak
Modular Libraries
Level 2: Publish modularized JAR
Preliminary results

44. @Sander_Mak
Modular Libraries
Level 2: Publish modularized JAR
Preliminary results
1%

45. @Sander_Mak
Modular Libraries
Level 2: Publish modularized JAR
Preliminary results
1%
Level 1: Automatic-Module-Name
9%

46. @Sander_Mak
Modular Libraries
Level 2: Publish modularized JAR
Preliminary results
1%
Level 1: Automatic-Module-Name
9%
Level 0: ¯_(ツ)_/¯
90%

47. @Sander_Mak
Modular Libraries
Level 1: Spring, Hibernate, Jackson & other popular libs

48. @Sander_Mak
Modular Libraries
bit.ly/automaticmods
Urge library maintainers to
step up to at least Level 1
Level 1: Spring, Hibernate, Jackson & other popular libs

49. @Sander_Mak
Modular Libraries
AdoptOpenJDK
+
bit.ly/automaticmods
Urge library maintainers to
step up to at least Level 1
Level 1: Spring, Hibernate, Jackson & other popular libs

50. @Sander_Mak
Let's Talk About Java EE

51. @Sander_Mak
Let's Talk About Java EE
Jakarta EE

52. @Sander_Mak
bit.ly/jakartaee
Jakarta EE

53. @Sander_Mak
bit.ly/jakartaee
Jakarta EE

54. @Sander_Mak
bit.ly/jakartaee Embrace modules:
Modularized artifacts
Platform-wide structure
Optional modules
Jakarta EE

55. @Sander_Mak
Modules:
java.xml.bind
java.xml.ws
java.ws.rs
java.mail
java.json
...
Automatic modules:
java.persistence
java.transaction
java.activation
...
Jakarta EE

56. @Sander_Mak
Module-aware
WARs?
EARs?

57. @Sander_Mak
Module-aware
WARs?
EARs?
Enterprise
Edition
-
Call for pricing1

58. @Sander_Mak
Let's Talk About Tooling

59. @Sander_Mak
Let's Talk About Tooling

60. @Sander_Mak

61. @Sander_Mak
pom.xml
module1/
pom.xml
/src/main/java
/module-info.java
/com/m1/Mod1.java
module2/
pom.xml
/src/main/java
/module-info.java
/com/m2/Mod2.java

62. @Sander_Mak
pom.xml
module1/
pom.xml
/src/main/java
/module-info.java
/com/m1/Mod1.java
module2/
pom.xml
/src/main/java
/module-info.java
/com/m2/Mod2.java

63. @Sander_Mak
pom.xml
module1/
pom.xml
/src/main/java
/module-info.java
/com/m1/Mod1.java
module2/
pom.xml
/src/main/java
/module-info.java
/com/m2/Mod2.java
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<release>11</release>
</configuration>
</plugin>

64. @Sander_Mak
Demo

65. @Sander_Mak

66. @Sander_Mak

67. @Sander_Mak

68. @Sander_Mak
guides.gradle.org/building-java-9-modules/
While Gradle version 4.10-rc-2
doesn’t have first-class support
for Java 9 modules yet, this guide
shows you how to experiment
with them before that support is
complete.

69. @Sander_Mak
guides.gradle.org/building-java-9-modules/
While Gradle version 4.10-rc-2
doesn’t have first-class support
for Java 9 modules yet, this guide
shows you how to experiment
with them before that support is
complete.

70. @Sander_Mak
guides.gradle.org/building-java-9-modules/
While Gradle version 4.10-rc-2
doesn’t have first-class support
for Java 9 modules yet, this guide
shows you how to experiment
with them before that support is
complete.

71. @Sander_Mak
guides.gradle.org/building-java-9-modules/
While Gradle version 4.10-rc-2
doesn’t have first-class support
for Java 9 modules yet, this guide
shows you how to experiment
with them before that support is
complete.

72. @Sander_Mak
22 June 2017
guides.gradle.org/building-java-9-modules/
While Gradle version 4.10-rc-2
doesn’t have first-class support
for Java 9 modules yet, this guide
shows you how to experiment
with them before that support is
complete.

73. @Sander_Mak
22 June 2017

74. @Sander_Mak
Fear No More!

75. @Sander_Mak
Fear No More!

76. @Sander_Mak
Fear No More!
github.com/java9-modularity/gradle-modules-plugin

77. @Sander_Mak
Let's Talk About Tooling
IDE

78. @Sander_Mak

79. @Sander_Mak

80. @Sander_Mak

81. @Sander_Mak
Let's Talk About Tooling
MISC

82. @Sander_Mak
Black Box Testing

83. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
Black Box Testing

84. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
Black Box Testing

85. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
Black Box Testing
mylibrary.itest.Test
mylibrary.itest
requires

86. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
Black Box Testing
mylibrary.itest.Test
mylibrary.itest
requires

87. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
White Box Testing

88. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
White Box Testing
mylibrary.impl.Test
mylibrary

89. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary
JUnit5 + junit-platform-maven-plugin
White Box Testing
mylibrary.impl.Test
mylibrary
--patch-module

90. @Sander_Mak
mylibrary.api
mylibrary.impl
mylibrary.impl.Test
mylibrary
JUnit5 + junit-platform-maven-plugin
White Box Testing
mylibrary.impl.Test
mylibrary
--patch-module

91. @Sander_Mak
jlink

92. @Sander_Mak
jlink
+
main
lib1 lib2
jdk
~300mb
application
~2mb

93. @Sander_Mak
jlink
+
main
lib1 lib2
jdk
~300mb
application
~2mb JVM
main
lib1 lib2
java.base
java.logging
java.xml
Custom Run-time Image
~25mb

94. @Sander_Mak
jlink
+
main
lib1 lib2
jdk
~300mb
application
~2mb JVM
main
lib1 lib2
java.base
java.logging
java.xml
Custom Run-time Image

95. @Sander_Mak
IoT Device
jlink
+
main
lib1 lib2
jdk
~300mb
application
~2mb JVM
main
lib1 lib2
java.base
java.logging
java.xml
Custom Run-time Image

96. @Sander_Mak
ModiTect Manage module-info in Maven

97. @Sander_Mak
ModiTect
<groupId>org.moditect</groupId>
<artifactId>moditect-maven-plugin</artifactId>
...
<module>
<moduleInfo>
<name>easytext.gui</name>
<exports>javamodularity.easytext.api.*;</exports>
<opens>javamodularity.easytext.gui to javafx.graphics;</opens>
<addServiceUses>true</addServiceUses>
</moduleInfo>
<mainClass>javamodularity.easytext.gui.Main</mainClass>
</module>
Manage module-info in Maven

98. @Sander_Mak
ModiTect
<groupId>org.moditect</groupId>
<artifactId>moditect-maven-plugin</artifactId>
...
<module>
<moduleInfo>
<name>easytext.gui</name>
<exports>javamodularity.easytext.api.*;</exports>
<opens>javamodularity.easytext.gui to javafx.graphics;</opens>
<addServiceUses>true</addServiceUses>
</moduleInfo>
<mainClass>javamodularity.easytext.gui.Main</mainClass>
</module>
Manage module-info in Maven

99. @Sander_Mak
ModiTect
<groupId>org.moditect</groupId>
<artifactId>moditect-maven-plugin</artifactId>
...
<module>
<moduleInfo>
<name>easytext.gui</name>
<exports>javamodularity.easytext.api.*;</exports>
<opens>javamodularity.easytext.gui to javafx.graphics;</opens>
<addServiceUses>true</addServiceUses>
</moduleInfo>
<mainClass>javamodularity.easytext.gui.Main</mainClass>
</module>
Manage module-info in Maven

100. @Sander_Mak
ModiTect
<groupId>org.moditect</groupId>
<artifactId>moditect-maven-plugin</artifactId>
...
<module>
<moduleInfo>
<name>easytext.gui</name>
<exports>javamodularity.easytext.api.*;</exports>
<opens>javamodularity.easytext.gui to javafx.graphics;</opens>
<addServiceUses>true</addServiceUses>
</moduleInfo>
<mainClass>javamodularity.easytext.gui.Main</mainClass>
</module>
Manage module-info in Maven

101. @Sander_Mak
ModiTect
Add module descriptors to existing JARs
Use jlink with automatic modules too
Create Docker + custom-runtime image
You can keep your build on Java 8

102. @Sander_Mak
It's Time to Wrap Up

103. @Sander_Mak

104. @Sander_Mak
Java 9
Java 10

105. @Sander_Mak
Java
9
Java
10

106. @Sander_Mak

107. @Sander_Mak
"It is too early to say whether
modules will achieve widespread
use outside of the JDK itself. In
the meantime, it seems best to
avoid them unless you have a
compelling need."
-- Josh Bloch

108. @Sander_Mak
"It is too early to say whether
modules will achieve widespread
use outside of the JDK itself. In the
meantime, it seems best to see for
yourself whether a modular
approach fits your codebase."
-- Sander Mak

109. Thanks. Read More:
javamodularity.com
@Sander_Mak
bit.ly/ps-sander