How to use Google Maven Central mirror?

By Wayan in Maven, Tools 1 Comment

The following configuration will use Google’s mirror of the Maven Central repository. Alter your ${M2_HOME}/conf/settings.xml or ${user.home}/.m2/settings.xml to add the mirror as seen in the following configuration file.

<?xml version="1.0" encoding="UTF-8"?>
<settings>
    .
    .
    <mirrors>
        <mirror>
            <id>google-maven-central</id>
            <name>Google Maven Central</name>
            <url>https://maven-central.storage.googleapis.com</url>
            <mirrorOf>central</mirrorOf>
        </mirror>
    </mirrors>
    .
    .
</settings>

How to configure a proxy in Maven settings?

By Wayan in Maven, Tools 2 Comments

When we work behind a proxy server, we need to configure Maven to be able to connect to the internet. To enable proxy we can configure Maven settings.xml file, either in ${M2_HOME}/conf/settings.xml or ${user.home}/.m2/settings.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<settings>
    .
    .
    <proxies>
        <proxy>
            <id>my-proxy</id>
            <active>true</active>
            <protocol>http</protocol>
            <host>proxy.example.org</host>
            <port>8080</port>
            <username>username</username>
            <password>password</password>
            <nonProxyHosts>*.example.org|*.example.com</nonProxyHosts>
        </proxy>
    </proxies>
    .
    .
</settings>

The <proxy> element in the configuration above contains the information about the proxy server. These include information about the host, port, username and password. Set these elements to match your proxy server configuration.

How do I specify the Java compiler version in a pom.xml file?

By Wayan in Maven, Tools 0 Comment

When you need to compile a project for a specific Java version you can configure maven compiler plugin to set the source and the target version. The following pom.xml file configuration show you how to do it.

<project>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Invalid value for the source and the target version in our project will make our project compilation process failed. For example when we try to use the diamond operator (<>) which available in Java 7, while the maven compiler plugin is set to version 1.5, can produce compiler error like this:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project servlet-example: Compilation failure
[ERROR] /Users/wsaryada/Studio/kodejava.org/webapp-example/servlet-example/src/main/java/org/kodejava/example/servlet/SessionCounter.java:[10,51] diamond operator is not supported in -source 1.5
[ERROR] (use -source 7 or higher to enable diamond operator)

How do I install Gradle in Mac OS X?

By Wayan in Gradle, Tools 17 Comments
Gradle

In this post we will learn how to install Gradle in OS X. The following steps will guide our installation process to make Gradle available in our OS X machine. But before we start let’s take a look at the definition from wikipedia about Gradle.

Gradle is an open source build automation system that builds upon the concepts of Apache Ant and Apache Maven and introduces a Groovy-based domain-specific language (DSL) instead of the XML form used by Apache Maven of declaring the project configuration.

From: Wikipedia

I. Using Homebrew

The short and simple answer is to use the Homebrew package manager for macOS. You can visit the website for detail on how to install the Homebrew. But to help you, I’ve copied the online script to install it below:

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

After installing Homebrew, just type the following command to install Gradle.

brew install gradle

Now, if you want to do it manually, here are the steps 😉

II. Manual Installation Steps

1. Download Gradle

To download visit Gradle Releases Page. Download the complete distribution which includes binaries, sources and offline documentation. For example, you can download the latest release of Gradle, as of this update the version is gradle-4.0.2-all.zip.

2. Unpacking Gradle and Configure Environment Variables

  • Open Terminal.app.
  • Create a new directory sudo mkdir /usr/local/gradle.
  • Extract the downloaded Gradle distribution archive by executing sudo unzip gradle-4.0.2-all.zip -d /usr/local/gradle.
  • Edit .bash_profile in your home directory to add GRADLE_HOME variable with the following line export GRADLE_HOME=/usr/local/gradle/gradle-4.0.2
  • Also update the PATH variable to include $GRADLE_HOME/bin. If you don’t already have the PATH variable add the following line export PATH=$GRADLE_HOME/bin:$PATH
  • Run source ~/.bash_profile to executes the update version of .bash_profile. Or you can open a new Terminal.app to make this changes active.

3. Running the Installation

To test Gradle installation open the Terminal.app and execute gradle -v command. If your installation was correct you will see something like the following output:

$ gradle -v

------------------------------------------------------------
Gradle 4.0.2
------------------------------------------------------------

Build time:   2017-07-26 15:04:56 UTC
Revision:     108c593aa7b43852f39045337ee84ee1d87c87fd

Groovy:       2.4.11
Ant:          Apache Ant(TM) version 1.9.6 compiled on June 29 2015
JVM:          1.8.0_121 (Oracle Corporation 25.121-b13)
OS:           Mac OS X 10.12.6 x86_64

How do I install Oracle Java in Ubuntu Server 14.04?

By Wayan in Tools, Ubuntu 1 Comment

The easiest way to install Oracle Java (JDK) in Ubuntu is to use the WebUpd8 PPA. A PPA (Personal Package Archive) is a special software repository for uploading source packages to be build and published as an APT repository by Launchpad. This PPA will download the required files from Oracle and install JDK7 / JDK8 / JDK9.

The steps:

  • Login to Ubuntu server.
  • sudo apt-add-repository ppa:webupd8team/java

The apt-add-repository command add the ppa to the current repository. You will be prompted with information message about installation instructions with the detail url. You need to press ENTER key to continue the process to add the repository.

apt-add-repository

apt-add-repository

  • sudo apt-get update

This will update the package list from the repositories and update them to get the latest versions of the packages and their dependencies. It will update all repositories and PPAs.

apt-get update

apt-get update

  • sudo apt-get install oracle-java8-installer

This command will start the installation process, you will be prompted to accept the license agreement. Run sudo apt-get install oracle-java7-installer if you want to install JDK7 instead. This process will take sometime to finish depending on your connection speed. And if everything runs well you’ll get Java installed at the end of this process.

apt-get install oracle-java8-installer

apt-get install oracle-java8-installer

  • java -version

This command return the version of the installed JDK. In this case it should return something like:

java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)

The JDK8 will be installed in the /usr/lib/jvm/java-8-oracle directory. If you need to define the JAVA_HOME environment variable then it should be directed to this directory.