diff --git a/.gitignore b/.gitignore
index d3ffd6b..2e03ad7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,5 @@
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 
+.idea
+.gradle
diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..b8d807d
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,23 @@
+plugins {
+    id 'java'
+}
+
+group 'de.vanitasvitae'
+version '1.0-SNAPSHOT'
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+    // Apache Repository for Commons CLI
+    maven { url "https://repository.apache.org/content/groups/snapshots/" }
+}
+
+dependencies {
+    // Apache Commons CLI for parsing command line arguments
+    compile 'commons-cli:commons-cli:1.5-SNAPSHOT'
+
+
+    // Testing
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..d2c45a4
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.8-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..cccdd3d
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,172 @@
+#!/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 "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+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" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..e95643d
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,84 @@
+@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=
+
+@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
diff --git a/requirements.md b/requirements.md
new file mode 100644
index 0000000..031f399
--- /dev/null
+++ b/requirements.md
@@ -0,0 +1,42 @@
+Aufgabe:
+
+Erzeugen eines 8 stelligen Codes zum Bekleben von Tubes einer Biobank.
+
+·         Die Codes sollen die Zeichen a-z,A-Z,0-9 unterstützen.
+
+·         Hierbei sollen die ersten 3 Stellen die Studiennummer kodieren,
+
+·         die nächste Stelle den Probentyp
+
+·         und die letzten 4 Stellen die Probennummer hochgezählt.
+
+
+
+Eingabe:
+
+Angabe einer Studiennummer, eines Probentyps und einer gewünschten Anzahl.
+
+
+
+Ausgabe:
+
+Eine HTML-Darstellung der Etiketten. (Eine Tabelle reicht hier aus.)
+
+
+
+Technische Voraussetzungen:
+
+·         Das Programm soll in Java sein. Wir verwenden Spring und programmieren Web-Applikationen, dies ist für diese
+          Aufgabe aber nicht erforderlich. Eine Jar-Datei mit README (Bedienungsanleitung) reicht.
+
+·         Die Ausgabe kann eine HTML-Datei sein, die manuell geöffnet werden kann.
+
+·         Die Eingabe kann über die Kommandozeile erfolgen, oder über eine simple GUI.
+
+·         Es sollen 2 Studiennummern und 2 Probentypen vordefiniert werden (Hardcoded). Die Eingabe einer nicht
+          definierten Studie/Typ soll sinnvoll behandelt werden.
+
+    ·         Es wäre schön, wenn sich das Programm die aktuelle Nummer zu einer Studie/Typ merken würde und bei einem
+              neuen Start weiterzählt.
+
+·         Der Code sollte gut dokumentiert sein (auf Englisch)
\ No newline at end of file
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..7ee4c61
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'imi.codes'
+
diff --git a/src/main/java/de/vanitasvitae/imi/codes/Arguments.java b/src/main/java/de/vanitasvitae/imi/codes/Arguments.java
new file mode 100644
index 0000000..9f0b250
--- /dev/null
+++ b/src/main/java/de/vanitasvitae/imi/codes/Arguments.java
@@ -0,0 +1,56 @@
+package de.vanitasvitae.imi.codes;
+
+import org.apache.commons.cli.Option;
+import org.apache.commons.cli.Options;
+
+public class Arguments {
+
+    static final Option STUDY_NUMBER = Option.builder("s")
+            .longOpt("study")
+            .desc("Three-letter code of the associated study")
+            .required()
+            .hasArg()
+            .argName("SNR")
+            .build();
+
+    static final Option SAMPLE_TYPE = Option.builder("t")
+            .longOpt("type")
+            .desc("Type of the sample (b = blood, u = urine)")
+            .required(true)
+            .hasArg()
+            .argName("sample type")
+            .build();
+
+    static final Option OUTPUT_DESTINATION = Option.builder("o")
+            .longOpt("OUTPUT_DESTINATION")
+            .desc("Filename for the generated html output")
+            .hasArg()
+            .argName("file name")
+            .build();
+
+    static final Option EXTERNAL_BROWSER = Option.builder("b")
+            .longOpt("EXTERNAL_BROWSER")
+            .desc("Open the generated HTML output in a an external browser")
+            .build();
+
+    static final Option HELP = Option.builder("h")
+            .longOpt("help")
+            .desc("Print this help text")
+            .build();
+    /**
+     * Assemble and return the available command line options.
+     *
+     * @return command line options.
+     */
+    public static Options getCommandLineOptions() {
+        Options options = new Options();
+
+        options.addOption(STUDY_NUMBER);
+        options.addOption(SAMPLE_TYPE);
+        options.addOption(OUTPUT_DESTINATION);
+        options.addOption(EXTERNAL_BROWSER);
+        options.addOption(HELP);
+
+        return options;
+    }
+}
diff --git a/src/main/java/de/vanitasvitae/imi/codes/InputValidator.java b/src/main/java/de/vanitasvitae/imi/codes/InputValidator.java
new file mode 100644
index 0000000..892c8f7
--- /dev/null
+++ b/src/main/java/de/vanitasvitae/imi/codes/InputValidator.java
@@ -0,0 +1,47 @@
+package de.vanitasvitae.imi.codes;
+
+import java.util.regex.Pattern;
+
+public class InputValidator {
+
+    // Allowed characters
+    private static final String ALPHABET = "[a-zA-Z0-9]";
+
+    /*
+    REGEX pattern for study numbers. Allowed are all 3-letter numbers from the alphabet [a-zA-Z0-9].
+     */
+    private static final Pattern STUDY_NUMBER_MATCHER = Pattern.compile(ALPHABET+"{3}");
+
+    /*
+    REGEX pattern for sample numbers. Allowed are four-letter numbers from the alphabet [a-zA-Z0-9].
+     */
+    private static final Pattern SAMPLE_NUMBER_MATCHER = Pattern.compile(ALPHABET+"{4}");
+
+    /**
+     * Validate a given study number. Valid study numbers are 3-letter codes from the alphabet [a-zA-Z0-9].
+     *
+     * @param in input String
+     * @return unmodified input String if it matches.
+     * @throws IllegalArgumentException if the input String doesn't match the regex.
+     */
+    public static String validateStudyNumber(String in) {
+        if (!STUDY_NUMBER_MATCHER.matcher(in).matches()) {
+            throw new IllegalArgumentException("Study number does not match REGEX.");
+        }
+
+        return in;
+    }
+
+    /**
+     * Validate a given sample type. Valid types are found in {@link SampleType}.#
+     *
+     * @param in input String
+     * @return parsed {@link SampleType}.
+     *
+     * @throws IllegalArgumentException if the given String doesn't match a {@link SampleType}.
+     * @throws NullPointerException in case the given String is {@code null}.
+     */
+    public static SampleType validateSampleType(String in) {
+        return SampleType.valueOf(in);
+    }
+}
diff --git a/src/main/java/de/vanitasvitae/imi/codes/Main.java b/src/main/java/de/vanitasvitae/imi/codes/Main.java
new file mode 100644
index 0000000..25d1998
--- /dev/null
+++ b/src/main/java/de/vanitasvitae/imi/codes/Main.java
@@ -0,0 +1,48 @@
+package de.vanitasvitae.imi.codes;
+
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.CommandLineParser;
+import org.apache.commons.cli.DefaultParser;
+import org.apache.commons.cli.HelpFormatter;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
+
+public class Main {
+
+    private static final String NAME_JAR = "imicodes";
+    private static final String HELP_HEADER = "Generate ID codes for sample tubes.";
+    private static final String HELP_FOOTER = "\nAuthor: Paul Schaub <paul.schaub@wwu.de>";
+
+    public static void main(String[] args) {
+
+        Options options = Arguments.getCommandLineOptions();
+        CommandLineParser parser = new DefaultParser();
+
+        CommandLine arguments;
+        try {
+            arguments = parser.parse(options, args);
+        } catch (ParseException e) {
+            System.out.println(e.getMessage());
+            printHelp(options);
+            return;
+        }
+
+        if (arguments.hasOption(Arguments.HELP)) {
+            printHelp(options);
+            return;
+        }
+    }
+
+    /**
+     * Print a descriptive help text to the console.
+     *
+     * @param options {@link Options} for which we want to print a help text.
+     */
+    private static void printHelp(Options options) {
+        HelpFormatter formatter = new HelpFormatter();
+
+        formatter.printHelp(NAME_JAR, HELP_HEADER, options, HELP_FOOTER, true);
+    }
+
+
+}
diff --git a/src/main/java/de/vanitasvitae/imi/codes/SampleType.java b/src/main/java/de/vanitasvitae/imi/codes/SampleType.java
new file mode 100644
index 0000000..621aeea
--- /dev/null
+++ b/src/main/java/de/vanitasvitae/imi/codes/SampleType.java
@@ -0,0 +1,20 @@
+package de.vanitasvitae.imi.codes;
+
+public enum SampleType {
+
+    b("Blood"),
+    u("Urine"),
+    ;
+
+    // Members of the enum
+
+    private final String name;
+
+    SampleType(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+}