diff --git a/.idea/modules.xml b/.idea/modules.xml
index a7599ac..843b25d 100644
--- a/.idea/modules.xml
+++ b/.idea/modules.xml
@@ -2,12 +2,18 @@
 <project version="4">
   <component name="ProjectModuleManager">
     <modules>
+      <module fileurl="file://$PROJECT_DIR$/DHBWTest/DHBWTest.iml" filepath="$PROJECT_DIR$/DHBWTest/DHBWTest.iml" />
+      <module fileurl="file://$PROJECT_DIR$/Fahrzeug/Fahrzeug.iml" filepath="$PROJECT_DIR$/Fahrzeug/Fahrzeug.iml" />
       <module fileurl="file://$PROJECT_DIR$/Kapselung/Kapselung.iml" filepath="$PROJECT_DIR$/Kapselung/Kapselung.iml" />
+      <module fileurl="file://$PROJECT_DIR$/ModifyStringArrayList/ModifyStringArrayList.iml" filepath="$PROJECT_DIR$/ModifyStringArrayList/ModifyStringArrayList.iml" />
       <module fileurl="file://$PROJECT_DIR$/PassValid/PassValid.iml" filepath="$PROJECT_DIR$/PassValid/PassValid.iml" />
+      <module fileurl="file://$PROJECT_DIR$/Person/Person.iml" filepath="$PROJECT_DIR$/Person/Person.iml" />
       <module fileurl="file://$PROJECT_DIR$/Rechtschreibung/Rechtschreibung.iml" filepath="$PROJECT_DIR$/Rechtschreibung/Rechtschreibung.iml" />
       <module fileurl="file://$PROJECT_DIR$/SchiffeVersenken/SchiffeVersenken.iml" filepath="$PROJECT_DIR$/SchiffeVersenken/SchiffeVersenken.iml" />
+      <module fileurl="file://$PROJECT_DIR$/ThreadTask/ThreadTask.iml" filepath="$PROJECT_DIR$/ThreadTask/ThreadTask.iml" />
       <module fileurl="file://$PROJECT_DIR$/Welt/Welt.iml" filepath="$PROJECT_DIR$/Welt/Welt.iml" />
       <module fileurl="file://$PROJECT_DIR$/aviation/aviation.iml" filepath="$PROJECT_DIR$/aviation/aviation.iml" />
+      <module fileurl="file://$PROJECT_DIR$/density/density.iml" filepath="$PROJECT_DIR$/density/density.iml" />
       <module fileurl="file://$PROJECT_DIR$/.idea/dhbw.iml" filepath="$PROJECT_DIR$/.idea/dhbw.iml" />
     </modules>
   </component>
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 700a80a..1c81ecc 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -4,13 +4,28 @@
     <option name="autoReloadType" value="SELECTIVE" />
   </component>
   <component name="ChangeListManager">
-    <list default="true" id="7992561a-5a42-4f2e-a81a-79d8a9c03d77" name="Changes" comment="del out dir">
-      <change afterPath="$PROJECT_DIR$/PassValid/.gitignore" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/PassValid/PassValid.iml" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/PassValid/src/PassValid.java" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/Rechtschreibung/.gitignore" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/Rechtschreibung/Rechtschreibung.iml" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/Rechtschreibung/src/Rechtschreibung.java" afterDir="false" />
+    <list default="true" id="7992561a-5a42-4f2e-a81a-79d8a9c03d77" name="Changes" comment="more simple stuff">
+      <change afterPath="$PROJECT_DIR$/DHBWTest/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/DHBWTest/DHBWTest.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/DHBWTest/src/Main.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Fahrzeug/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Fahrzeug/Fahrzeug.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Fahrzeug/src/Fahrrad.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Fahrzeug/src/Fahrzeug.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ModifyStringArrayList/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ModifyStringArrayList/ModifyStringArrayList.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ModifyStringArrayList/src/ModifyStringArrayList.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ModifyStringArrayList/src/ModifyStringArrayListMain.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Person/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Person/Person.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Person/src/Person.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/Person/src/PersonMain.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ThreadTask/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ThreadTask/ThreadTask.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/ThreadTask/src/Main.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/density/.gitignore" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/density/density.iml" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/density/src/Density.java" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/modules.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/modules.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
     </list>
@@ -19,6 +34,13 @@
     <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
     <option name="LAST_RESOLUTION" value="IGNORE" />
   </component>
+  <component name="FileTemplateManagerImpl">
+    <option name="RECENT_TEMPLATES">
+      <list>
+        <option value="Class" />
+      </list>
+    </option>
+  </component>
   <component name="Git.Settings">
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
   </component>
@@ -30,29 +52,50 @@
     <option name="hideEmptyMiddlePackages" value="true" />
     <option name="showLibraryContents" value="true" />
   </component>
-  <component name="PropertiesComponent"><![CDATA[{
-  "keyToString": {
-    "ASKED_ADD_EXTERNAL_FILES": "true",
-    "ASKED_MARK_IGNORED_FILES_AS_EXCLUDED": "true",
-    "ASKED_SHARE_PROJECT_CONFIGURATION_FILES": "true",
-    "RunOnceActivity.ShowReadmeOnStart": "true",
-    "SHARE_PROJECT_CONFIGURATION_FILES": "true",
-    "git-widget-placeholder": "master",
-    "jdk.selected.JAVA_MODULE": "17",
-    "jdk.selected.com.intellij.ui.dsl.builder.impl.RowImpl.sdk": "17",
-    "last_opened_file_path": "/home/plex/Documents/code/java/dhbw",
-    "project.structure.last.edited": "Modules",
-    "project.structure.proportion": "0.0",
-    "project.structure.side.proportion": "0.0",
-    "settings.editor.selected.configurable": "preferences.lookFeel"
+  <component name="PropertiesComponent">{
+  &quot;keyToString&quot;: {
+    &quot;ASKED_ADD_EXTERNAL_FILES&quot;: &quot;true&quot;,
+    &quot;ASKED_MARK_IGNORED_FILES_AS_EXCLUDED&quot;: &quot;true&quot;,
+    &quot;ASKED_SHARE_PROJECT_CONFIGURATION_FILES&quot;: &quot;true&quot;,
+    &quot;RunOnceActivity.ShowReadmeOnStart&quot;: &quot;true&quot;,
+    &quot;SHARE_PROJECT_CONFIGURATION_FILES&quot;: &quot;true&quot;,
+    &quot;git-widget-placeholder&quot;: &quot;master&quot;,
+    &quot;jdk.selected.JAVA_MODULE&quot;: &quot;17&quot;,
+    &quot;jdk.selected.com.intellij.ui.dsl.builder.impl.RowImpl.sdk&quot;: &quot;17&quot;,
+    &quot;last_opened_file_path&quot;: &quot;/home/plex/Documents/code/java/dhbw&quot;,
+    &quot;project.structure.last.edited&quot;: &quot;Modules&quot;,
+    &quot;project.structure.proportion&quot;: &quot;0.0&quot;,
+    &quot;project.structure.side.proportion&quot;: &quot;0.0&quot;,
+    &quot;settings.editor.selected.configurable&quot;: &quot;preferences.lookFeel&quot;
   },
-  "keyToStringList": {
-    "jdk.preference.com.intellij.ui.dsl.builder.impl.RowImpl.sdk": [
-      "17=/usr/lib/jvm/java-17"
+  &quot;keyToStringList&quot;: {
+    &quot;jdk.preference.com.intellij.ui.dsl.builder.impl.RowImpl.sdk&quot;: [
+      &quot;17=/usr/lib/jvm/java-17&quot;
     ]
   }
-}]]></component>
-  <component name="RunManager" selected="Application.PassValid">
+}</component>
+  <component name="RunManager" selected="Application.Main">
+    <configuration name="Density" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="Density" />
+      <module name="density" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
+    <configuration name="Main" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="Main" />
+      <module name="ThreadTask" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
+    <configuration name="ModifyStringArrayListMain" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="ModifyStringArrayListMain" />
+      <module name="ModifyStringArrayList" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
     <configuration name="PassValid" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
       <option name="MAIN_CLASS_NAME" value="PassValid" />
       <module name="PassValid" />
@@ -60,33 +103,20 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
-    <configuration name="Rechtschreibung" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="Rechtschreibung" />
-      <module name="Rechtschreibung" />
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
-    <configuration name="SchiffeVersenken" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="SchiffeVersenken" />
-      <module name="SchiffeVersenken" />
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
-    <configuration name="Welt" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="Welt" />
-      <module name="Welt" />
+    <configuration name="PersonMain" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="PersonMain" />
+      <module name="Person" />
       <method v="2">
         <option name="Make" enabled="true" />
       </method>
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="Application.Main" />
+        <item itemvalue="Application.PersonMain" />
+        <item itemvalue="Application.ModifyStringArrayListMain" />
+        <item itemvalue="Application.Density" />
         <item itemvalue="Application.PassValid" />
-        <item itemvalue="Application.Rechtschreibung" />
-        <item itemvalue="Application.SchiffeVersenken" />
-        <item itemvalue="Application.Welt" />
       </list>
     </recent_temporary>
   </component>
@@ -141,7 +171,14 @@
       <option name="project" value="LOCAL" />
       <updated>1682343561370</updated>
     </task>
-    <option name="localTasksCounter" value="7" />
+    <task id="LOCAL-00007" summary="more simple stuff">
+      <created>1682344398810</created>
+      <option name="number" value="00007" />
+      <option name="presentableId" value="LOCAL-00007" />
+      <option name="project" value="LOCAL" />
+      <updated>1682344398810</updated>
+    </task>
+    <option name="localTasksCounter" value="8" />
     <servers />
   </component>
   <component name="Vcs.Log.Tabs.Properties">
@@ -174,7 +211,8 @@
     <MESSAGE value="weirdo intellij stuff" />
     <MESSAGE value="schiffe overengineered" />
     <MESSAGE value="del out dir" />
-    <option name="LAST_COMMIT_MESSAGE" value="del out dir" />
+    <MESSAGE value="more simple stuff" />
+    <option name="LAST_COMMIT_MESSAGE" value="more simple stuff" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
diff --git a/DHBWTest/.gitignore b/DHBWTest/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/DHBWTest/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/DHBWTest/DHBWTest.iml b/DHBWTest/DHBWTest.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/DHBWTest/DHBWTest.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/DHBWTest/src/Main.java b/DHBWTest/src/Main.java
new file mode 100644
index 0000000..3e59c38
--- /dev/null
+++ b/DHBWTest/src/Main.java
@@ -0,0 +1,5 @@
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file
diff --git a/Fahrzeug/.gitignore b/Fahrzeug/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/Fahrzeug/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/Fahrzeug/Fahrzeug.iml b/Fahrzeug/Fahrzeug.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/Fahrzeug/Fahrzeug.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/Fahrzeug/src/Fahrrad.java b/Fahrzeug/src/Fahrrad.java
new file mode 100644
index 0000000..264caf6
--- /dev/null
+++ b/Fahrzeug/src/Fahrrad.java
@@ -0,0 +1,3 @@
+public class Fahrrad extends Fahrzeug {
+
+}
\ No newline at end of file
diff --git a/Fahrzeug/src/Fahrzeug.java b/Fahrzeug/src/Fahrzeug.java
new file mode 100644
index 0000000..e172362
--- /dev/null
+++ b/Fahrzeug/src/Fahrzeug.java
@@ -0,0 +1,15 @@
+public class Fahrzeug {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+    private int max_speed;
+
+    public int getMax_speed() {
+        return max_speed;
+    }
+
+    public void setMax_speed(int max_speed) {
+        this.max_speed = max_speed;
+    }
+}
+
diff --git a/ModifyStringArrayList/.gitignore b/ModifyStringArrayList/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/ModifyStringArrayList/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/ModifyStringArrayList/ModifyStringArrayList.iml b/ModifyStringArrayList/ModifyStringArrayList.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/ModifyStringArrayList/ModifyStringArrayList.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/ModifyStringArrayList/src/ModifyStringArrayList.java b/ModifyStringArrayList/src/ModifyStringArrayList.java
new file mode 100644
index 0000000..a78e033
--- /dev/null
+++ b/ModifyStringArrayList/src/ModifyStringArrayList.java
@@ -0,0 +1,29 @@
+import java.util.ArrayList;
+
+public interface ModifyStringArrayList {
+
+    /**
+     * @author Christoph J. Scherr <software@cscherr.de>
+     * @param als
+     * @return als but reversed
+     */
+    public ArrayList<String> listeUmdrehen(ArrayList<String> als);
+    /**
+     * @author Christoph J. Scherr <software@cscherr.de>
+     * @param als
+     * @return als but shuffled
+     */
+    public ArrayList<String> listeMischen(ArrayList<String> als);
+    /**
+     * @author Christoph J. Scherr <software@cscherr.de>
+     * @param als
+     * @return max of als
+     */
+    public String listeMaxElement(ArrayList<String> als);
+    /**
+     * @author Christoph J. Scherr <software@cscherr.de>
+     * @param als
+     * @return max of als
+     */
+    public String listeMinElement(ArrayList<String> als);
+}
diff --git a/ModifyStringArrayList/src/ModifyStringArrayListMain.java b/ModifyStringArrayList/src/ModifyStringArrayListMain.java
new file mode 100644
index 0000000..84897e4
--- /dev/null
+++ b/ModifyStringArrayList/src/ModifyStringArrayListMain.java
@@ -0,0 +1,30 @@
+import java.util.ArrayList;
+import java.util.Collections;
+
+public class ModifyStringArrayListMain implements ModifyStringArrayList{
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+
+    @Override
+    public ArrayList<String> listeUmdrehen(ArrayList<String> als) {
+        Collections.reverse(als);
+        return als;
+    }
+
+    @Override
+    public ArrayList<String> listeMischen(ArrayList<String> als) {
+        Collections.shuffle(als);
+        return als;
+    }
+
+    @Override
+    public String listeMaxElement(ArrayList<String> als) {
+        return Collections.max(als);
+    }
+
+    @Override
+    public String listeMinElement(ArrayList<String> als) {
+        return Collections.min(als);
+    }
+}
\ No newline at end of file
diff --git a/Person/.gitignore b/Person/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/Person/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/Person/Person.iml b/Person/Person.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/Person/Person.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/Person/src/Person.java b/Person/src/Person.java
new file mode 100644
index 0000000..8da0b0b
--- /dev/null
+++ b/Person/src/Person.java
@@ -0,0 +1,20 @@
+import java.util.Scanner;
+
+public class Person {
+    private static Person INSTANCE;
+
+    private String name;
+    private String date;
+    public static Person getInstance(String name, String date) {
+        if(INSTANCE == null) {
+            INSTANCE = new Person();
+            INSTANCE.name = name;
+            INSTANCE.date = date;
+        }
+        else {
+            System.out.println("An instance already exists, ignoring args");
+        }
+        return INSTANCE;
+    }
+    private Person() {}
+}
\ No newline at end of file
diff --git a/Person/src/PersonMain.java b/Person/src/PersonMain.java
new file mode 100644
index 0000000..f6bd29a
--- /dev/null
+++ b/Person/src/PersonMain.java
@@ -0,0 +1,13 @@
+import java.util.Scanner;
+
+public class PersonMain {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        String name = scanner.nextLine();
+        String date = scanner.nextLine();
+        Person p = Person.getInstance(name, date);
+        Person p2 = Person.getInstance(name, date);
+        assert p == p2;
+        System.out.println("Same person");
+    }
+}
diff --git a/ThreadTask/.gitignore b/ThreadTask/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/ThreadTask/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/ThreadTask/ThreadTask.iml b/ThreadTask/ThreadTask.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/ThreadTask/ThreadTask.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/ThreadTask/src/Main.java b/ThreadTask/src/Main.java
new file mode 100644
index 0000000..74f5f1e
--- /dev/null
+++ b/ThreadTask/src/Main.java
@@ -0,0 +1,37 @@
+public class Main implements Runnable {
+    private boolean oddTaken = false;
+    private int max;
+    private String name = "t0";
+    public static void main(String[] args) throws InterruptedException {
+        Main m0 = new Main();
+        Main m1 = new Main();
+        Thread t0 = new Thread(m0);
+        Thread t1 = new Thread(m1);
+        m0.max = 0xf000000;
+        m1.max = 0xf000000;
+        m1.oddTaken = true;
+        m1.name = "t1";
+        t0.start();
+        t1.start();
+        t0.join();
+        t1.join();
+    }
+
+    @Override
+    public void run() {
+        System.out.println("Thread start");
+        int i;
+        if (!oddTaken) {
+            // do the odds
+            i = 1;
+        }
+        else {
+            // do the equals
+            i = 0;
+        }
+        while (i < max) {
+            System.out.println(name + " - " + i);
+            i += 2;
+        }
+    }
+}
\ No newline at end of file
diff --git a/density/.gitignore b/density/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/density/.gitignore
@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/density/density.iml b/density/density.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/density/density.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/density/src/Density.java b/density/src/Density.java
new file mode 100644
index 0000000..41b8c86
--- /dev/null
+++ b/density/src/Density.java
@@ -0,0 +1,35 @@
+import java.util.Scanner;
+public class Density {
+    /**
+     * Folgende Formel soll berechnet werden: Dichte = Masse /Volumen
+     * Das Volumen darf nicht 0 sein, sonst kommt es zu einem Fehler
+     * Fange in diesem Fall den Fehler ab und gib eine Rückmeldung
+     * Konnte die Formel berechnet werden, soll das Ergebnis ausgegeben werden
+     * Erweitere die Aufgabe um folgende Punkte:
+     * Das Volumen soll nun nicht negativ und nicht über 1000 sein
+     * hierfür soll ein Fehler ausgeworfen werden
+     * Dieser soll wiederum abgefangen werden
+     */
+    public static void main(String[] args) {
+
+        try {
+            Scanner scanner = new Scanner(System.in);
+            System.out.println("input volume");
+            int volume = scanner.nextInt();
+            if (volume == 0) {
+                throw new ArithmeticException("volume must not be 0");
+            } else if (volume < 0) {
+                throw new ArithmeticException("volume must not be positive");
+            } else if (volume >= 1000) {
+                throw new ArithmeticException("volume must not be more than 1000");
+            }
+            System.out.println("input mass");
+            int mass = scanner.nextInt();
+            // does not throw an division by 0 exception for float datatypes, instead says that density is 'Infinity'
+            float density = (float) mass / volume;
+            System.out.printf("density: %f%n", density);
+        } catch (ArithmeticException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+}
\ No newline at end of file