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About Mary Zheng

Mary has graduated from Mechanical Engineering department at ShangHai JiaoTong University. She also holds a Master degree in Computer Science from Webster University. During her studies she has been involved with a large number of projects ranging from programming and software engineering. She works as a senior Software Engineer in the telecommunications sector where she acts as a leader and works with others to design, implement, and monitor the software solution.

Java 8 vs Java 9

In this article, we’re going to present Java 8 vs Java 9.

1. Introduction

Java is an object-oriented programming language and first released in 1995. Java 8 is the first long-term-support (LTS) version and released in 2014. The current LTS version is 11. Java 9 is released in 2017. According to this article, Java 8 is the most popular version. The most significant new feature in Java 8 is the lambda expression. The most noticeable new feature in Java 9 is the Java Platform Module System.

Most Significant FeaturesJava Example Link
Java 8Lambda Expression
Stream API
https://examples.javacodegeeks.com/java-8-api-tutorial/
Java 9Module
JShell
https://examples.javacodegeeks.com/how-to-download-and-install-java-9/

In this example, I will show the key differences in Spring Tools Suite (STS) for Java 8 and Java 9.

2. Technologies Used

  • OpenJDK 11
  • Maven 3.6
  • STS 4.10

3. STS IDE

Prior to Java 9, a Java application groups classes into a package. Java 9 application can define a module which groups packages and specifies which packages are exposed outside of the module. In this step, I will outline the STS IDE support for Java 9.

3.1 Java Build Path

STS IDE provides four tabs for Java Build Path prior to Java 9. See Figure 1 for Java 8 build path settings.

java 9 vs java 8 - java 8 build path
Figure 1 Java 8 build Path

STS IDE adds a new tab – Module Dependencies to support Java 9. See Figure 2 for Java 9 build path settings.

java 9 vs java 8 - java 9 build path
Figure 2 Java 9 build Path

As you seen at Figure 2, there are several buttons to update the Modulepath and Classpath.

4. Java Commands

4.1 –list-modules option

Java add –list-modules option to show all the modules packaged with installed JDK.

java –list-modules

C:\MaryZheng\sts_4_10_ws\jdk9-demo>java --list-modules
java.base@11.0.2
java.compiler@11.0.2
java.datatransfer@11.0.2
java.desktop@11.0.2
java.instrument@11.0.2
java.logging@11.0.2
java.management@11.0.2
java.management.rmi@11.0.2
java.naming@11.0.2
java.net.http@11.0.2
java.prefs@11.0.2
java.rmi@11.0.2
java.scripting@11.0.2
java.se@11.0.2
java.security.jgss@11.0.2
java.security.sasl@11.0.2
java.smartcardio@11.0.2
java.sql@11.0.2
java.sql.rowset@11.0.2
java.transaction.xa@11.0.2
java.xml@11.0.2
java.xml.crypto@11.0.2
jdk.accessibility@11.0.2
jdk.aot@11.0.2
jdk.attach@11.0.2
jdk.charsets@11.0.2
jdk.compiler@11.0.2
jdk.crypto.cryptoki@11.0.2
jdk.crypto.ec@11.0.2
jdk.crypto.mscapi@11.0.2
jdk.dynalink@11.0.2
jdk.editpad@11.0.2
jdk.hotspot.agent@11.0.2
jdk.httpserver@11.0.2
jdk.internal.ed@11.0.2
jdk.internal.jvmstat@11.0.2
jdk.internal.le@11.0.2
jdk.internal.opt@11.0.2
jdk.internal.vm.ci@11.0.2
jdk.internal.vm.compiler@11.0.2
jdk.internal.vm.compiler.management@11.0.2
jdk.jartool@11.0.2
jdk.javadoc@11.0.2
jdk.jcmd@11.0.2
jdk.jconsole@11.0.2
jdk.jdeps@11.0.2
jdk.jdi@11.0.2
jdk.jdwp.agent@11.0.2
jdk.jfr@11.0.2
jdk.jlink@11.0.2
jdk.jshell@11.0.2
jdk.jsobject@11.0.2
jdk.jstatd@11.0.2
jdk.localedata@11.0.2
jdk.management@11.0.2
jdk.management.agent@11.0.2
jdk.management.jfr@11.0.2
jdk.naming.dns@11.0.2
jdk.naming.rmi@11.0.2
jdk.net@11.0.2
jdk.pack@11.0.2
jdk.rmic@11.0.2
jdk.scripting.nashorn@11.0.2
jdk.scripting.nashorn.shell@11.0.2
jdk.sctp@11.0.2
jdk.security.auth@11.0.2
jdk.security.jgss@11.0.2
jdk.unsupported@11.0.2
jdk.unsupported.desktop@11.0.2
jdk.xml.dom@11.0.2
jdk.zipfs@11.0.2

4.2 –describe-module option

Java tool command adds –describe-module option to print out the detail of the module. In the following command, it will print out the detail about the java.sql module.

java –describe-module java.sql

C:\MaryZheng\DevTools\Java\JDK11\bin>java --describe-module java.sql
java.sql@11.0.2
exports java.sql
exports javax.sql
requires java.base mandated
requires java.xml transitive
requires java.logging transitive
requires java.transaction.xa transitive
uses java.sql.Driver

In the following command, it prints out the module details of money-api-1.1.jar.

jar –file=C:\repo\javax\money\money-api\1.1\money-api-1.1.jar –describe-module

C:\MaryZheng\sts_4_10_ws\jdk9-demo>jar --file=C:\repo\javax\money\money-api\1.1\money-api-1.1.jar --describe-module
java.money jar:file:///C:/repo/javax/money/money-api/1.1/money-api-1.1.jar/!module-info.class
exports javax.money
exports javax.money.convert
exports javax.money.format
exports javax.money.spi
requires java.base
requires java.logging
uses javax.money.convert.ExchangeRateProvider
uses javax.money.spi.CurrencyProviderSpi
uses javax.money.spi.MonetaryAmountFactoryProviderSpi
uses javax.money.spi.MonetaryAmountFormatProviderSpi
uses javax.money.spi.MonetaryAmountsSingletonQuerySpi
uses javax.money.spi.MonetaryAmountsSingletonSpi
uses javax.money.spi.MonetaryConversionsSingletonSpi
uses javax.money.spi.MonetaryCurrenciesSingletonSpi
uses javax.money.spi.MonetaryFormatsSingletonSpi
uses javax.money.spi.MonetaryRoundingsSingletonSpi
uses javax.money.spi.RoundingProviderSpi
uses javax.money.spi.ServiceProvider

Note: the module name: java.money is different from jar name: money-api.

The following command prints out the moneta details.

jar –file=C:\repo\org\javamoney\moneta\1.1\moneta-1.1.jar –describe-module

C:\MaryZheng\sts_4_10_ws\jdk9-demo>jar --file=C:\repo\org\javamoney\moneta\1.1\moneta-1.1.jar --describe-module
No module descriptor found. Derived automatic module.

moneta@1.1 automatic
requires java.base mandated
provides javax.money.convert.ExchangeRateProvider with org.javamoney.moneta.internal.convert.ECBCurrentRateProvider org.javamoney.moneta.internal.convert.ECBHistoric90RateProvider org.javamoney.moneta.internal.convert.ECBHistoricRateProvider org.javamoney.moneta.internal.convert.IMFHistoricRateProvider org.javamoney.moneta.internal.convert.IMFRateProvider org.javamoney.moneta.internal.convert.IdentityRateProvider
provides javax.money.spi.CurrencyProviderSpi with org.javamoney.moneta.internal.ConfigurableCurrencyUnitProvider org.javamoney.moneta.internal.JDKCurrencyProvider
provides javax.money.spi.MonetaryAmountFactoryProviderSpi with org.javamoney.moneta.internal.FastMoneyAmountFactoryProvider org.javamoney.moneta.internal.MoneyAmountFactoryProvider org.javamoney.moneta.internal.RoundedMoneyAmountFactoryProvider
provides javax.money.spi.MonetaryAmountFormatProviderSpi with org.javamoney.moneta.internal.format.DefaultAmountFormatProviderSpi
provides javax.money.spi.MonetaryAmountsSingletonQuerySpi with org.javamoney.moneta.internal.DefaultMonetaryAmountsSingletonQuerySpi
provides javax.money.spi.MonetaryAmountsSingletonSpi with org.javamoney.moneta.internal.DefaultMonetaryAmountsSingletonSpi
provides javax.money.spi.MonetaryConversionsSingletonSpi with org.javamoney.moneta.internal.convert.DefaultMonetaryConversionsSingletonSpi
provides javax.money.spi.MonetaryCurrenciesSingletonSpi with org.javamoney.moneta.internal.DefaultMonetaryCurrenciesSingletonSpi
provides javax.money.spi.RoundingProviderSpi with org.javamoney.moneta.internal.DefaultRoundingProvider
provides javax.money.spi.ServiceProvider with org.javamoney.moneta.internal.PriorityAwareServiceProvider
provides org.javamoney.moneta.spi.LoaderService with org.javamoney.moneta.internal.loader.DefaultLoaderService
contains org.javamoney.moneta
contains org.javamoney.moneta.convert
contains org.javamoney.moneta.format
contains org.javamoney.moneta.function
contains org.javamoney.moneta.internal
contains org.javamoney.moneta.internal.convert
contains org.javamoney.moneta.internal.format
contains org.javamoney.moneta.internal.loader
contains org.javamoney.moneta.spi

Note: this moneta.jar is not created as a Java 9 module, so it is an automatic module with the name as the jar file name.

5. Create a Simple Java 9 Module

5.1 Pom.xml

In this step, I will create a pom.xml file which includes two dependencies.

pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>jcg.zheng.demo</groupId>
	<artifactId>jdk9-demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<build>
		<sourceDirectory>src</sourceDirectory>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.1</version>
				<configuration>
					<release>11</release>
					<showWarnings>true</showWarnings>
					<showDeprecation>true</showDeprecation>
				</configuration>

			</plugin>
		</plugins>
	</build>
	<dependencies>
		<dependency>
			<groupId>javax.money</groupId>
			<artifactId>money-api</artifactId>
			<version>1.1</version>
		</dependency>
		<dependency>
			<groupId>org.javamoney</groupId>
			<artifactId>moneta</artifactId>
			<version>1.1</version>
		</dependency>
	</dependencies>
</project>

5.2 module-info.java

In this step, I will create a module-info.java file which requires three modules and exports one package.

module-info.java

module module1 {
	requires java.base;
	
	requires java.money;
	requires moneta;

	exports org.jcg.zheng.demo;
}

5.3 MoneyDemo

In this step, I will create a MoneyDemo class which calculates money for US currency. Please note all the money objects are immutable.

MoneyDemo.java

package org.jcg.zheng.demo;

import java.util.Locale;

import javax.money.Monetary;
import javax.money.MonetaryAmount;
import javax.money.format.AmountFormatQueryBuilder;
import javax.money.format.MonetaryAmountFormat;
import javax.money.format.MonetaryFormats;

import org.javamoney.moneta.format.CurrencyStyle;

public class MoneyDemo {

	public static void main(String[] args) {
		MonetaryAmount oneDollar = Monetary.getDefaultAmountFactory().setCurrency("USD").setNumber(1).create();
		MonetaryAmount twoDollar = Monetary.getDefaultAmountFactory().setCurrency("USD").setNumber(2).create();

		System.out.println("Curreny=" + oneDollar.getCurrency().toString());

		MonetaryAmount threeDollar = oneDollar.add(twoDollar);

		System.out.println(oneDollar.toString());
		System.out.println(twoDollar.toString());
		System.out.println(threeDollar.toString());
		
		MonetaryAmountFormat customFormat = MonetaryFormats.getAmountFormat(AmountFormatQueryBuilder.of(Locale.US)
				.set(CurrencyStyle.NAME).set("pattern", "00.00 US Dollar").build());

		System.out.println(customFormat.format(oneDollar));
		System.out.println(customFormat.format(twoDollar));
		System.out.println(customFormat.format(threeDollar));

	}

}

5.4 Demo

This MoneyDemo depends on two third-party modules, so make sure that the depended modules are added in the Modulepath. See Figure 3 for Modulepath details.

java 9 vs java 8 - module path
Figure 4 Module Path

Click the “Module Dependencies” tab to see the module’s dependencies. See Figure 4.

Figure 4 Module Dependencies

Run the MoneyDemo class as a Java application and capture the output here.

MoneyDemo output

May 31, 2021 10:27:53 AM org.javamoney.moneta.DefaultMonetaryContextFactory createMonetaryContextNonNullConfig
INFO: Using custom MathContext: precision=256, roundingMode=HALF_EVEN
Curreny=USD
USD 1
USD 2
USD 3
01.00 US Dollar
02.00 US Dollar
03.00 US Dollar

Note: oneDollar, twoDollar, and threeDollar are immutable.

6. Summary

In this example, I explained the key features (along with example link) introduced at Java 8 and Java 9. I also demonstrated the following new features at Java 9:

  • STS IDE build path is updated to include module dependencies.
  • Java tool command is updated to describe modules.
  • How to include modules in the Java 9 module project.
  • How to export Java packages inside a module.

Please note that Java 9 is not a LTS version and the current LTS version is 11.

7. More articles

8. Download the Source Code

Download
You can download the full source code of this example here: Java 8 vs Java 9

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