Java project using maven

Building and Running a Java SE Application by Using Maven

In this tutorial, you create and build a Java Platform, Standard Edition (Java SE) application using Maven. You install, configure, build, and create an executable Java Archive (JAR) file with Maven.

Time to Complete

Background

Maven is a build management tool that is central to project build tasks such as compilation, packaging, and artifact management. Maven uses a strict XML-based rule set to promote consistency while maintaining flexibility. Because most Java-centric continuous integration systems integrate well with Maven, it’s a good choice for an underlying build system.

• A project model that is reusable, maintainable, and easier to comprehend
• Plug-ins or tools that interact with the declarative model

• Local Repository: The location created on your machine when you run your first instance of a Maven command in your machine
• Central Repository: The Maven community-owned repository that contains commonly used libraries
• Remote Repository: A developer-owned custom repository that contains project-related libraries and JARs

What Do You Need?

• Download and install the latest Java SE Development Kit. For this tutorial, the available version is Java SE 8.
• Download the Apache Maven. For this tutorial, the available version is 3.2.2.

Setting Up the Maven Environment

In this section, you extract the downloaded archive and install the latest Maven version to a directory of your choice. You verify the Java installation, set the Maven environment, and verify the Maven installation.

1. Verify the Java installation:
   java -version The output displays the Java version that you installed.
2. Extract the downloaded Maven x.x.x archive to a local directory. The archive names are:
   • Windows OS: apache-maven-3.2.2-bin.zip
   • Linux OS: apache-maven-3.2.2-bin.tar.gz
   • Mac OS: apache-maven-3.2.2-bin.tar.gz

Note: This OBE shows you how to install and create a Java SE application using Maven in a Windows operating system.

Click Start, right-click Computer, and select Properties.

On the Control Panel home page, click Advanced system settings.

In the System Properties dialog box, click the Advanced tab, and then click Environment Variables.
The Environment Variables dialog box is displayed.

Click New, add M2, M2_HOME, and MAVEN_OPTS to the environment variables, and click OK.

Verify the Maven installation: mvn -version The output displays the installed Maven version, the Java version, the Java home, the Default locale, and the OS name.

Creating a Java SE Project from a Maven Template

Open the command prompt, navigate to the directory where you installed Maven, and create Maven_app, a Maven-based Java application folder: mvn archetype:generate -DgroupId=com.example.bank
-DartifactId=OracleBanking
-DarchetypeArtifactId=maven-archetype-quickstart
-DinteractiveMode=false An archetype is an original pattern/model for creating similar projects. In Maven, an archetype is a template of a project that is combined with user input to produce a working Maven project. The following table describes what the template does:

The Java project named OracleBanking is created. The following table presents the project details:

Open the OracleBanking project and verify the Java source file: App.java

Verify Java test file:
AppTest.java By default, Maven adds the App.java source file and the AppTest.java test file to the default directory structure.

Open the pom.xml file and review the code. Each project has a single pom.xml file, and each pom.xml file has a project element and three mandatory fields: groupId, artifactId, and version. Notice that Maven has already added JUnit as the test framework. The following table describes what each node does:

Node	Description
project	Top-level element in all Maven pom.xml files
modelVersion	Object model version that this POM is using
groupId	Project groupId (for example, com.example.bank )
artifactId	Project ID (for example, OracleBanking )
packaging	Project files converted into a JAR file
version	Project version used in the artifact’s repository to separate each version (for example, 1.0-SNAPSHOT )
name	Project display name
url	Location of the project site

Creating and Modifying Java Source Files

In this section, you calculate simple interest by creating the SimpleInterest.java source file and modifying the App.java source file.

1. Navigate to the directory where you created your Maven project, and then open the specified location: \**\Maven_app\OracleBanking\src\main\java\com\example\bank
2. Create a Java source file named SimpleInterest.java.
3. Edit the SimpleInterest.java file with the following code:

package com.example.bank; public class SimpleInterest < public static double calculateSimpleInterest(double amount, double years, double rate_of_interest) < double simple_interest; simple_interest = amount * years * rate_of_interest; return simple_interest; >> 

double result = SimpleInterest.calculateSimpleInterest(10000, 5, 7); System.out.println("The simple interest is:" + result); public static double calculateSimpleInterest(double amount, double years, double rate_of_interest)

Creating a Manifest with Maven

In this section, you learn how to use maven-jar-plugin to create a manifest file and package it by adding it to the JAR file.

• Defines the entry point of the project and creates an executable JAR file.
• Adds the class path of the project dependencies.

   org.apache.maven.plugins maven-jar-plugin 2.4   com.example.bank.App       

You defined maven-jar-plugin in pom.xml, and configured it within the configuration tag.

 double result=App.calculateSimpleInterest(10000,5,7); Assert.assertEquals("Test failed. ",35000.0,result);

Review the code. It should look like the following: You modified the simple interest value, and then verified the value by using assert statements in the JUnit test case.

Review the output. The test case failed and the assert failed message is displayed.

 Assert.assertEquals("Test failed. ", 350000.0, result);

Press Ctrl+S and then run the test cases in AppTest.java: mvn test The test case executed successfully, and a build success message is displayed.

Building the Application

In this section, you learn how to clean and build your application using the Maven CLI.

1. Clean and build your Maven project, and review the output: mvn clean package
   You successfully built the OracleBanking Java SE application using Maven.
2. Navigate to the directory where you created OracleBanking and notice that a target folder was created.
3. Open the target folder, and review the folder structure.
   

   Folder name	Description
   classes	Contains .class files of Java source files
   test-classes	Contains .class files of Java test files
   maven-archiver	Contains the pom.properties file
   surefire-reports	Contains the report of the application when mvn command is executed.
   java	Empty Java file
   OracleBanking-1.0-SNAPSHOT.jar	Contains all the project related details in a single zip file. This is the executable JAR file used to run the application

Packaging and Running the Application

In this section, you learn how to package and run the Java SE project using the Maven CLI.

1. Navigate to the directory where you installed Maven, and open the settings.xml file. The tag specifies the local repository location on your machine. By default, the local repository is created in the %USER_HOME% directory. You can specify another location by updating it in the settings.xml file. If you need to set proxy details for the application, then update it in the settings.xml file.
2. Clean and package the files, plug-ins, and libraries before running the application: mvn clean package
3. Use the Maven Local repository to run your Java SE Maven application: mvn exec:java -Dexec.mainClass=»com.example.bank.App» -s «*****location of settings.xml file.********»
4. Review the output. You successfully executed the Java SE application named OracleBanking using Maven. The simple interest is calculated and displayed in the Maven CLI.
5. Execute the JAR file with following commands: cd target
   java -jar OracleBanking-1.0-SNAPSHOT.jar
6. Review the output. You successfully executed the OracleBanking Java SE application by using Maven. The simple interest is calculated and displayed in the Maven CLI.

Want to Learn More?

• Maven Quick Guide
• Maven Getting Started Guide
• Installing and Configuring Maven for Build Automation and Dependency Managementin Oracle Fusion Middleware Developing Applications Using Continuous Integration

Credits

To navigate this Oracle by Example tutorial, note the following:

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