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# Ignore Gradle project-specific cache directory
# Created by https://www.gitignore.io/api/java,linux,macos,gradle,windows,eclipse,intellij
# Edit at https://www.gitignore.io/?templates=java,linux,macos,gradle,windows,eclipse,intellij
### Eclipse ###
.metadata
bin/
tmp/
*.tmp
*.bak
*.swp
*~.nib
local.properties
.settings/
.loadpath
.recommenders
# External tool builders
.externalToolBuilders/
# Locally stored "Eclipse launch configurations"
*.launch
# PyDev specific (Python IDE for Eclipse)
*.pydevproject
# CDT-specific (C/C++ Development Tooling)
.cproject
# CDT- autotools
.autotools
# Java annotation processor (APT)
.factorypath
# PDT-specific (PHP Development Tools)
.buildpath
# sbteclipse plugin
.target
# Tern plugin
.tern-project
# TeXlipse plugin
.texlipse
# STS (Spring Tool Suite)
.springBeans
# Code Recommenders
.recommenders/
# Annotation Processing
.apt_generated/
# Scala IDE specific (Scala & Java development for Eclipse)
.cache-main
.scala_dependencies
.worksheet
### Eclipse Patch ###
# Eclipse Core
.project
# JDT-specific (Eclipse Java Development Tools)
.classpath
# Annotation Processing
.apt_generated
.sts4-cache/
### Intellij ###
# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and WebStorm
# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
# User-specific stuff
.idea/**/workspace.xml
.idea/**/tasks.xml
.idea/**/usage.statistics.xml
.idea/**/dictionaries
.idea/**/shelf
# Generated files
.idea/**/contentModel.xml
# Sensitive or high-churn files
.idea/**/dataSources/
.idea/**/dataSources.ids
.idea/**/dataSources.local.xml
.idea/**/sqlDataSources.xml
.idea/**/dynamic.xml
.idea/**/uiDesigner.xml
.idea/**/dbnavigator.xml
# Gradle
.idea/**/gradle.xml
.idea/**/libraries
# Gradle and Maven with auto-import
# When using Gradle or Maven with auto-import, you should exclude module files,
# since they will be recreated, and may cause churn. Uncomment if using
# auto-import.
# .idea/modules.xml
# .idea/*.iml
# .idea/modules
# *.iml
# *.ipr
# CMake
cmake-build-*/
# Mongo Explorer plugin
.idea/**/mongoSettings.xml
# File-based project format
*.iws
# IntelliJ
out/
# mpeltonen/sbt-idea plugin
.idea_modules/
# JIRA plugin
atlassian-ide-plugin.xml
# Cursive Clojure plugin
.idea/replstate.xml
# Crashlytics plugin (for Android Studio and IntelliJ)
com_crashlytics_export_strings.xml
crashlytics.properties
crashlytics-build.properties
fabric.properties
# Editor-based Rest Client
.idea/httpRequests
# Android studio 3.1+ serialized cache file
.idea/caches/build_file_checksums.ser
### Intellij Patch ###
# Comment Reason: https://github.com/joeblau/gitignore.io/issues/186#issuecomment-215987721
# *.iml
# modules.xml
# .idea/misc.xml
# *.ipr
# Sonarlint plugin
.idea/sonarlint
### Java ###
# Compiled class file
*.class
# Log file
*.log
# BlueJ files
*.ctxt
# Mobile Tools for Java (J2ME)
.mtj.tmp/
# Package Files #
# *.jar
*.war
*.nar
*.ear
*.zip
*.tar.gz
*.rar
# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
### Linux ###
*~
# temporary files which can be created if a process still has a handle open of a deleted file
.fuse_hidden*
# KDE directory preferences
.directory
# Linux trash folder which might appear on any partition or disk
.Trash-*
# .nfs files are created when an open file is removed but is still being accessed
.nfs*
### macOS ###
# General
.DS_Store
.AppleDouble
.LSOverride
# Icon must end with two \r
Icon
# Thumbnails
._*
# Files that might appear in the root of a volume
.DocumentRevisions-V100
.fseventsd
.Spotlight-V100
.TemporaryItems
.Trashes
.VolumeIcon.icns
.com.apple.timemachine.donotpresent
# Directories potentially created on remote AFP share
.AppleDB
.AppleDesktop
Network Trash Folder
Temporary Items
.apdisk
### Windows ###
# Windows thumbnail cache files
Thumbs.db
Thumbs.db:encryptable
ehthumbs.db
ehthumbs_vista.db
# Dump file
*.stackdump
# Folder config file
[Dd]esktop.ini
# Recycle Bin used on file shares
$RECYCLE.BIN/
# Windows Installer files
*.cab
*.msi
*.msix
*.msm
*.msp
# Windows shortcuts
*.lnk
### Maven ###
target/
### Gradle ###
.gradle
build/
# Ignore Gradle GUI config
gradle-app.setting
# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
!gradle-wrapper.jar
# Cache of project
.gradletasknamecache
# # Work around https://youtrack.jetbrains.com/issue/IDEA-116898
# gradle/wrapper/gradle-wrapper.properties
### Gradle Patch ###
**/build/
# Ignore Gradle build output directory
build
# End of https://www.gitignore.io/api/java,linux,macos,gradle,windows,eclipse,intellij
image: gradle:jdk12
before_script:
- export GRADLE_USER_HOME=`pwd`/.gradle
cache:
paths:
- .gradle/wrapper
- .gradle/caches
image: maven:3.9.9-eclipse-temurin-17
build:
stage: build
script:
- ./gradlew -Pci=gitlab build
- mvn "-Dci=gitlab" process-resources
pages:
script:
- mvn "-Dci=gitlab" process-resources
- cp -r target/docs/* public
# only:
# - master
artifacts:
paths:
- lectures/build/docs
expire_in: 1 week
- public
FROM gitpod/workspace-full-vnc
USER gitpod
# Install custom tools, runtime, etc. using apt-get
# For example, the command below would install "bastet" - a command line tetris clone:
#
# RUN sudo apt-get -q update && # sudo apt-get install -yq bastet && # sudo rm -rf /var/lib/apt/lists/*
#
# More information: https://www.gitpod.io/docs/config-docker/
tasks:
- init: echo "Replace me with a build script for the project."
command: echo "Replace me with something that should run on every start, or just
remove me entirely."
image:
file: .gitpod.Dockerfile
Hallvard Trætteberg <hal@ntnu.no> Hallvard Trætteberg <hal@ntnu.no>
Hallvard Trætteberg <hal@ntnu.no> Hallvard Traetteberg <hal@ntnu.no>
Adrian Stoica <george.a.stoica@ntnu.no> Adrian Stoica <george.a.stoica@ntnu.no>
Adrian Stoica <george.a.stoica@ntnu.no> georgeas <george.a.stoica@ntnu.no>
Adrian Stoica <george.a.stoica@ntnu.no> George Adrian Stoica <george.a.stoica@ntnu.no>
Pål-Edward Larsen <paaledwl@stud.ntnu.no> Pål-Edward Larsen <paaledwl@stud.ntnu.no>
Pål-Edward Larsen <paaledwl@stud.ntnu.no> paaledwl <paaledwl@stud.ntnu.no>
{
// See https://go.microsoft.com/fwlink/?LinkId=733558
// for the documentation about the tasks.json format
"version": "2.0.0",
"tasks": [
{
"label": "gradle run",
"type": "shell",
"command": "gradle",
"args": ["run"]
},
{
"label": "gradle version",
"type": "shell",
"command": "gradle",
"args": ["--version"]
},
{
"label": "java -version",
"type": "shell",
"command": "java",
"args": ["-version"]
},
{
"label": "sdk use java 12.0.2-open",
"type": "shell",
"command": "sdk",
"args": ["use", "java", "12.0.2-open"]
}
]
}
\ No newline at end of file
## Installation
### Install Java
#### [Guide for installing Java Development Kit](https://gitlab.stud.idi.ntnu.no/it1901/course-material/blob/master/howto/get-java.md "Installing Java")
#### Download links
* http://jdk.java.net
* https://www.oracle.com/technetwork/java/javase/downloads/index.html
#### How and why to uninstall older versions of Java
https://www.java.com/en/download/faq/remove_olderversions.xml
### Install Git
#### Download link
https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
#### For Windows we recommend Git for Windows
https://gitforwindows.org/
### Install Eclipse or Intellij
#### Intellij download link (download the free community edition)
https://www.jetbrains.com/idea/download/#section=mac
#### Eclipse for Java download link
https://www.eclipse.org/downloads/packages/release/2019-06/r/eclipse-ide-java-developers
## Update the local project credentials to match your Gitlab user.
1) Open the terminal window and go to your Gitlab project
2) Update local user email with 'git config --local user.email YOUR_NTNU_USERNAME@stud.ntnu.no'
3) Update local user password with 'git config --local user.password YOUR_NTNU_PASSWORD'
4) Update local user username with 'git config --local user.name YOUR_NTNU_USERNAME'
## How to clone video
VIDEO: https://vimeo.com/355521976
[![Gitpod Ready-to-Code](https://img.shields.io/badge/Gitpod-Ready--to--Code-blue?logo=gitpod)](https://gitpod.idi.ntnu.no/#https://gitlab.stud.idi.ntnu.no/it1901/course-material)
# course-material
Course material for IT1901
\ No newline at end of file
target/
.classpath
.project
<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>it1901</groupId>
<artifactId>antipatterns</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!-- Test with JUnit5 -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.4.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>5.4.2</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Compiling code -->
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<encoding>UTF-8</encoding>
<release>13</release>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>3.0.0-M5</version>
<!--
<configuration>
<argLine>${argLine} dash dash add-exports javafx.graphics/com.sun.javafx.application=ALL-UNNAMED</argLine>
</configuration>
-->
</plugin>
</plugins>
</build>
</project>
\ No newline at end of file
package antipatterns;
public class DataClassWithEffectivelyFinalFields {
private final String name; // should be final
private final int number; // should be final
public DataClassWithEffectivelyFinalFields(final String name, final int number) {
this.name = name;
this.number = number;
}
public String getName() {
return name;
}
public int getNumber() {
return number;
}
}
package antipatterns;
// ok, but see the test
public class DataClassWithLittleLogic {
private String name;
private int number;
public DataClassWithLittleLogic(final String name, final int number) {
this.name = name;
this.number = number;
}
@Override
public String toString() {
return String.format("[DataClassWithLittleLogic name=%s number=%s]", name, number);
}
public DataClassWithLittleLogic() {
}
public String getName() {
return name;
}
public void setName(final String name) {
this.name = name;
}
public int getNumber() {
return number;
}
public void setNumber(final int number) {
this.number = number;
}
}
package antipatterns;
// see DataClassWithValidationTest
public class DataClassWithValidation {
private String name;
public DataClassWithValidation(final String name) {
// should use setName to ensure validation logic is run
this.name = name;
}
public DataClassWithValidation() {
}
public String getName() {
return name;
}
public void setName(final String name) {
if (name.startsWith(" ")) {
// should rather use trim() or strip() and check the length
throw new IllegalArgumentException("Name cannot begin with blank");
}
this.name = name;
}
}
package antipatterns;
import java.util.Collection;
import java.util.Iterator;
public class NonEncapsulatedList implements Iterable<String> {
private final Collection<String> names;
public NonEncapsulatedList(final Collection<String> names) {
this.names = names;
}
public Collection<String> getNames() {
return names;
}
public Iterator<String> iterator() {
return names.iterator();
}
}
package antipatterns;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
public class DataClassWithLittleLogicTest {
private DataClassWithLittleLogic instance1, instance2;
@BeforeEach
public void setup() {
instance1 = new DataClassWithLittleLogic();
instance2 = new DataClassWithLittleLogic("High", 5);
}
@Test
public void testConstructor() {
Assertions.assertEquals("High", instance2.getName());
}
@Test
public void testToString() {
Assertions.assertEquals("[DataClassWithLittleLogic name=High number=5]", instance2.toString());
}
@Test
public void testSetName() {
instance1.setName("Low");
Assertions.assertEquals("Low", instance1.getName());
}
}
package antipatterns;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
public class DataClassWithValidationTest {
@Test
public void testSetName() {
try {
new DataClassWithValidation(" name starting with blank");
Assertions.fail("Should throw IllegalArgumentException");
} catch (final IllegalArgumentException iae) {
} catch (final Exception iae) {
Assertions.fail("Should throw IllegalArgumentException");
}
try {
new DataClassWithValidation("ok name");
} catch (final Exception iae) {
Assertions.fail();
}
}
@Test
public void testBetterSetName_invalidName() {
Assertions.assertThrows(IllegalArgumentException.class, () -> new DataClassWithValidation(" name starting with blank"));
}
@Test
public void testBetterSetName_validName() {
new DataClassWithValidation("ok name");
}
}
#!/usr/bin/env sh
##############################################################################
##
## Gradle start up script for UN*X
##
##############################################################################
# Attempt to set APP_HOME
# Resolve links: $0 may be a link
PRG="$0"
# Need this for relative symlinks.
while [ -h "$PRG" ] ; do
ls=`ls -ld "$PRG"`
link=`expr "$ls" : '.*-> \(.*\)$'`
if expr "$link" : '/.*' > /dev/null; then
PRG="$link"
else
PRG=`dirname "$PRG"`"/$link"
fi
done
SAVED="`pwd`"
cd "`dirname \"$PRG\"`/" >/dev/null
APP_HOME="`pwd -P`"
cd "$SAVED" >/dev/null
APP_NAME="Gradle"
APP_BASE_NAME=`basename "$0"`
# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
DEFAULT_JVM_OPTS='"-Xmx64m"'
# Use the maximum available, or set MAX_FD != -1 to use that value.
MAX_FD="maximum"
warn () {
echo "$*"
}
die () {
echo
echo "$*"
echo
exit 1
}
# OS specific support (must be 'true' or 'false').
cygwin=false
msys=false
darwin=false
nonstop=false
case "`uname`" in
CYGWIN* )
cygwin=true
;;
Darwin* )
darwin=true
;;
MINGW* )
msys=true
;;
NONSTOP* )
nonstop=true
;;
esac
CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
# Determine the Java command to use to start the JVM.
if [ -n "$JAVA_HOME" ] ; then
if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
# IBM's JDK on AIX uses strange locations for the executables
JAVACMD="$JAVA_HOME/jre/sh/java"
else
JAVACMD="$JAVA_HOME/bin/java"
fi
if [ ! -x "$JAVACMD" ] ; then
die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation."
fi
else
JAVACMD="java"
which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation."
fi
# Increase the maximum file descriptors if we can.
if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
MAX_FD_LIMIT=`ulimit -H -n`
if [ $? -eq 0 ] ; then
if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
MAX_FD="$MAX_FD_LIMIT"
fi
ulimit -n $MAX_FD
if [ $? -ne 0 ] ; then
warn "Could not set maximum file descriptor limit: $MAX_FD"
fi
else
warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
fi
fi
# For Darwin, add options to specify how the application appears in the dock
if $darwin; then
GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
fi
# For Cygwin, switch paths to Windows format before running java
if $cygwin ; then
APP_HOME=`cygpath --path --mixed "$APP_HOME"`
CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
JAVACMD=`cygpath --unix "$JAVACMD"`
# We build the pattern for arguments to be converted via cygpath
ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
SEP=""
for dir in $ROOTDIRSRAW ; do
ROOTDIRS="$ROOTDIRS$SEP$dir"
SEP="|"
done
OURCYGPATTERN="(^($ROOTDIRS))"
# Add a user-defined pattern to the cygpath arguments
if [ "$GRADLE_CYGPATTERN" != "" ] ; then
OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
fi
# Now convert the arguments - kludge to limit ourselves to /bin/sh
i=0
for arg in "$@" ; do
CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option
if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition
eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
else
eval `echo args$i`="\"$arg\""
fi
i=$((i+1))
done
case $i in
(0) set -- ;;
(1) set -- "$args0" ;;
(2) set -- "$args0" "$args1" ;;
(3) set -- "$args0" "$args1" "$args2" ;;
(4) set -- "$args0" "$args1" "$args2" "$args3" ;;
(5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
(6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
(7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
(8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
(9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
esac
fi
# Escape application args
save () {
for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
echo " "
}
APP_ARGS=$(save "$@")
# Collect all arguments for the java command, following the shell quoting and substitution rules
eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
cd "$(dirname "$0")"
fi
exec "$JAVACMD" "$@"
@if "%DEBUG%" == "" @echo off
@rem ##########################################################################
@rem
@rem Gradle startup script for Windows
@rem
@rem ##########################################################################
@rem Set local scope for the variables with windows NT shell
if "%OS%"=="Windows_NT" setlocal
set DIRNAME=%~dp0
if "%DIRNAME%" == "" set DIRNAME=.
set APP_BASE_NAME=%~n0
set APP_HOME=%DIRNAME%
@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
set DEFAULT_JVM_OPTS="-Xmx64m"
@rem Find java.exe
if defined JAVA_HOME goto findJavaFromJavaHome
set JAVA_EXE=java.exe
%JAVA_EXE% -version >NUL 2>&1
if "%ERRORLEVEL%" == "0" goto init
echo.
echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.
goto fail
:findJavaFromJavaHome
set JAVA_HOME=%JAVA_HOME:"=%
set JAVA_EXE=%JAVA_HOME%/bin/java.exe
if exist "%JAVA_EXE%" goto init
echo.
echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.
goto fail
:init
@rem Get command-line arguments, handling Windows variants
if not "%OS%" == "Windows_NT" goto win9xME_args
:win9xME_args
@rem Slurp the command line arguments.
set CMD_LINE_ARGS=
set _SKIP=2
:win9xME_args_slurp
if "x%~1" == "x" goto execute
set CMD_LINE_ARGS=%*
:execute
@rem Setup the command line
set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
@rem Execute Gradle
"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
:end
@rem End local scope for the variables with windows NT shell
if "%ERRORLEVEL%"=="0" goto mainEnd
:fail
rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
rem the _cmd.exe /c_ return code!
if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
exit /b 1
:mainEnd
if "%OS%"=="Windows_NT" endlocal
:omega
# Setting up Java
![](logos/java.png)
To be able to develop in Java one requires a JDK - Java Development Kit. You have to download and properly set up java
For IT1901 either JDK 11 or 12 will do just fine.
Installing manually the jdk has the following steps no matter what operating system you are using:
* download the archive containing the desired release
* extract it
* move it to a meaningful location (depends on the os what is a good location)
* set up environment variables for `JAVA_HOME` and `PATH`
* apply changes if necessary
Note: The examples shown here use filenames as they were for jdk 12.0.2 at the moment of redacting the document. Adjust the filenames and the paths as needed. Depending on your OS version or flavour you might have different text editors and you might need to adjust for that as well.
## Install java
If there is no Java Development Kit installed or the version is not what you need (we recommend version 11 or 12) then proceed to download JDK and install it.
### Windows
#### Check if there is any java installed
In a command line window type:
``` batch
java -version
```
![](images/04%20-%20check%20for%20java%20windows.png)
#### Extract downloaded binary
After the download finishes you have in the destination folder the `.zip` file with a name like this `openjdk-12.0.2_windows-x64_bin.zip`. Right click it and extract the contents.
![](images/05%20-%20extract%20openjdk%20windows.png)
Copy the extracted folder in a meaningful location on your hard drive like for example in `C:\jdks`
![](images/06%20-%20move%20the%20jdk%20folder%20to%20c-jdks%20folder.png)
#### Set up the environment variables
To properly set up Java on your machine you need to set couple environment variables. To do that you need to open "Environment variables" dialog box.
There are several ways to get to that dialog box.
Right click "This PC" and select "Properties"
![](images/07%20-%20open%20pc%20properties.png)
You should see a window like the one below. Choose "Advanced System Settings" option in the top left side.
![](images/08%20-%20pc%20properties%20window.png)
A new window will open showing "System properties"
![](images/09%20-%20system%20properties.png)
Open "Environment Variables"
If the JDK should be available for all users than make the environment variable changes at system level otherwise do them at user level.
Check if there is already a `JAVA_HOME` environment variable. If it is change the value to the path to your JDK (`C:\jdks\jdk-12.0.2`)
![](images/10%20-%20env%20java%20home.png)
Next we need to add the `bin` folder within the JDK folder to the `PATH` environment variable so that the java commands are accessible from the command prompt
![](images/11%20-%20env%20path.png)
Finally we can check if java is now running as expected
![](images/12%20-%20java%20check%20ok.png)
##### Notes
* You can check the values of environment variables from command prompt issuing commands such as `SET JAVA_HOME` or `SET PATH`
* You can get to the environment variable dialog by other means
- search "env" in the windows start menu
- open System from the Control Panel and then "Environment Variables"
### Linux
#### Check if there is any java installed
Open a terminal window and type
``` bash
java -version
```
![](images/linux03_check_false.png)
#### Extract downloaded binary
After the download finishes you have in the destination folder the `.tar.gz` file with a name like this `openjdk-12.0.2_linux-x64_bin.tar.gz` .
Extract the files and place them in the desired location with the following commands
``` bash
tar zxvf openjdk-12.0.2_linux-x64_bin.tar.gz
sudo mkdir /usr/lib/jvm
sudo mv jdk-12.0.2 /usr/lib/jvm/
```
![](images/linux02_extract.png)
![](images/linux04_move.png)
#### Set up the environment variables
create a shell script in /etc/profile.d
``` bash
sudo nano /etc/profile.d/jdk.sh
```
![](images/linux05_env01.png)
add the following lines inside the file and save and close
``` bash
export JAVA_HOME=/usr/lib/jvm/jdk-12.0.2
export PATH=$PATH:$JAVA_HOME/bin
```
![](images/linux06_env02.png)
apply changes
logout and log back in or run the script you have just created
``` bash
bash /etc/profile.d/jdk.sh
```
check if everything is in order
``` bash
echo $JAVA_HOME
java -version
```
![](images/linux07_check_true.png)
### MacOs
#### Check if there is any java installed
Open a terminal window and type
``` bash
java -version
```
![](images/mac_02_check_false.png)
#### Extract downloaded binary
After the download finishes you have in the destination folder the `.tar.gz` file with a name like this `openjdk-12.0.2_osx-x64_bin.tar.gz`.
Extract the files using the following command
``` bash
tar xf openjdk-12.0.2_osx-x64_bin.tar.gz
```
![](images/mac_03_extract.png)
Move the extracted to the folder `/Library/Java/JavaVirtualMachines/`
You will need to execute the move with super user privileges in order to put the files in the system folder
``` bash
sudo mv jdk-12.0.2.jdk /Library/Java/JavaVirtualMachines/
```
![](images/mac_04_move.png)
#### Set up the environment variables
To set up the environment variable `JAVA_HOME` we will need to edit the `.bash_profile` file in the home directory.
If the file mentioned does not exist we can create it with the following command:
``` bash
touch ~/.bash_profile
```
![](images/mac_05_env01.png)
We need to export the `JAVA_HOME` variable so we edit the file using
``` bash
edit ~/.bash_profile
```
or
``` bash
nano ~/.bash_profile
```
![](images/mac_06_env02.png)
we add the following line
`export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk-12.0.2.jdk/Contents/Home"`
![](images/mac_08_env03.png)
finally we save the changes and close the file. To apply the changes we need to run the following command
``` bash
source ~/.bash_profile
```
![](images/mac_07_apply_env.png)
check if everything is in order
![](images/mac_09_check_true.png)
## Using sdkman
sdkman is a tool that allows you to manage development kits including JDK. It is possible to run it on Linux and Mac without additional software. On windows one can use it after installing Git Bash and MinGW.
Refer to the https://sdkman.io webpage for more info and instructions
### Installation on supported systems - open a terminal window and enter:
``` bash
curl -s "https://get.sdkman.io" | bash
```
Follow the instructions on-screen to complete installation.
Apply changes by entering:
``` bash
source "$HOME/.sdkman/bin/sdkman-init.sh"
```
check the version using the command
``` bash
sdk version
```
If the tool is now properly installed the result of the previous command will be:
``` bash
sdkman 5.x.x
```
### Typical usage
After installation you will typically use commands like
``` bash
sdk list java
```
list the available versions
``` bash
sdk install java
```
install latest java, add version number to install specific java
``` bash
sdk use java 12.0.2
```
use the java development kit with version 12.0.2
See more commands on the sdkman.io site
## Download Java
### Open-source reference implementation (GNU GPL License, provided by Oracle)
* 1. go to http://jdk.java.net
![](images/01%20-%20jdk.java.net%20-%20home.png)
* 2. select the general available build (currently 12)
![](images/02%20-%20jdk.java.net%20-%20latest%20ga.png)
* 3. download the binary corresponding to your operating system
### Get binaries from Oracle site (Oracle license)
1. go to https://www.oracle.com/technetwork/java/javase/downloads/index.html
2. sign in (if you do not have an account you will need to create one in order to be allowed to download)
3. select the latest (currently 12)
4. download the binary corresponding to your operating system
There are more choices for downloads. Typically a .zip or .tar.gz would imply manual setup while the .exe, .deb, .rpm, .dmg will provide some sort of installer support.
For the .zip or .tar.gz files you need to follow the procedure from above.
.exe (windows) - run and follow the installer prompts
.dmg (mac) - run and follow the installer prompts
.deb (linux) - package format used in Debian and Ubuntu linux distributions
```bash
sudo dpkg -i ~/Downloads/jdk-12.0.2_linux-x64_bin.deb
```
alternative way to install .deb packages is with apt
```bash
sudo apt install ~/Downloads/jdk-12.0.2_linux-x64_bin.deb
```
In Ubuntu you can also double click the package and it will open in Software Center where there is an option to install it.
.rpm (linux) - package format commonly used in Redhat and Mandrake linux distributions
``` bash
rpm -ivh ~/Downloads/jdk-12.0.2_linux-x64_bin.rpm
```
howto/images/01 - jdk.java.net - home.png

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