diff --git a/client/app/src/main/java/main/CreateEventController.java b/client/app/src/main/java/main/CreateEventController.java
index 14d52d3..d77c407 100644
--- a/client/app/src/main/java/main/CreateEventController.java
+++ b/client/app/src/main/java/main/CreateEventController.java
@@ -3,10 +3,7 @@ package main;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
-import javafx.scene.control.CheckBox;
-import javafx.scene.control.ComboBox;
-import javafx.scene.control.DatePicker;
-import javafx.scene.control.TextField;
+import javafx.scene.control.*;
 import javafx.stage.Stage;
 import res.DataController;
 import res.Event;
@@ -29,39 +26,50 @@ public class CreateEventController {
     public CheckBox checkBoxIsFullDay;
     @FXML
     public CheckBox checkBoxIsPrivate;
-
-
-    public CreateEventController(){}
-
     @FXML
-    public void initialize(){}
+    public Label labelError;
 
 
-    @FXML
-    protected void createBtnClick(ActionEvent actionEvent){
-
-        Event event = new Event(
-                textName.getText(),
-                ComboBoxPriotity.getSelectionModel().getSelectedIndex(),
-                checkBoxIsFullDay.isSelected(),
-                checkBoxIsPrivate.isSelected(),
-                textStart.getText(),
-                textEnd.getText(),
-                datePickerDate.getValue().atStartOfDay(),
-                1
-        );
-
-        System.out.println(event.getAsUrlParam());
-
-        DataController dataController = new DataController();
-        dataController.createEvent(event);
-
-        Stage stage = (Stage) ((Node) actionEvent.getSource()).getScene().getWindow();
-        stage.close();
+    public CreateEventController() {
     }
 
     @FXML
-    protected void abortBtnClick(ActionEvent event){
+    public void initialize() {
+    }
+
+
+    @FXML
+    protected void createBtnClick(ActionEvent actionEvent) {
+        try {
+            if (datePickerDate.getValue() == null) {
+                throw new IllegalArgumentException("Bitte w\u00e4hle ein Datum aus");
+            }
+
+            Event event = new Event(
+                    textName.getText(),
+                    ComboBoxPriotity.getSelectionModel().getSelectedIndex(),
+                    checkBoxIsFullDay.isSelected(),
+                    checkBoxIsPrivate.isSelected(),
+                    textStart.getText(),
+                    textEnd.getText(),
+                    datePickerDate.getValue().atStartOfDay(),
+                    (int) DataController.USER_ID
+            );
+
+            System.out.println(event.getAsUrlParam());
+
+            DataController dataController = new DataController();
+            dataController.createEvent(event);
+
+            Stage stage = (Stage) ((Node) actionEvent.getSource()).getScene().getWindow();
+            stage.close();
+        } catch (RuntimeException e) {
+            labelError.setText(e.getMessage());
+        }
+    }
+
+    @FXML
+    protected void abortBtnClick(ActionEvent event) {
         Stage stage = (Stage) ((Node) event.getSource()).getScene().getWindow();
         stage.close();
     }
diff --git a/client/app/src/main/java/main/Launcher.java b/client/app/src/main/java/main/Launcher.java
index fd5d4c8..38c385d 100644
--- a/client/app/src/main/java/main/Launcher.java
+++ b/client/app/src/main/java/main/Launcher.java
@@ -1,7 +1,7 @@
 package main;
 
 public class Launcher {
-    
+
     public static void main(String[] args) {
         MainApplication.main(args);
     }
diff --git a/client/app/src/main/java/main/MainApplication.java b/client/app/src/main/java/main/MainApplication.java
index ac5f771..6efcaa1 100644
--- a/client/app/src/main/java/main/MainApplication.java
+++ b/client/app/src/main/java/main/MainApplication.java
@@ -4,6 +4,7 @@ import javafx.application.Application;
 import javafx.fxml.FXMLLoader;
 import javafx.scene.Scene;
 import javafx.stage.Stage;
+import res.DataController;
 
 import java.io.IOException;
 import java.util.Objects;
@@ -14,19 +15,23 @@ public class MainApplication extends Application {
         FXMLLoader fxmlLoader = new FXMLLoader(MainApplication.class.getResource("main-view.fxml"));
 
         Scene scene = new Scene(fxmlLoader.load(), 1200, 700);
-        scene.getStylesheets().add(Objects.requireNonNull(MainApplication.class.getResource("main-view.css")).toExternalForm());
+        scene.getStylesheets().add(Objects.requireNonNull(
+                MainApplication.class.getResource("main-view.css")).toExternalForm());
         stage.setTitle("SharePlaner");
         stage.setScene(scene);
-        stage.show();
 
         FXMLLoader fxmlLoaderLogin = new FXMLLoader(MainApplication.class.getResource("../users/login.fxml"));
         Scene sceneLogin = new Scene(fxmlLoaderLogin.load(), 650, 500);
-        sceneLogin.getStylesheets().add(Objects.requireNonNull(MainApplication.class.getResource("../users/login.css")).toExternalForm());
+        sceneLogin.getStylesheets().add(Objects.requireNonNull(
+                MainApplication.class.getResource("../users/login.css")).toExternalForm());
         Stage stageLogin = new Stage();
         stageLogin.setTitle("Anmelden");
         stageLogin.setScene(sceneLogin);
-        stageLogin.show();
+        stageLogin.showAndWait();
 
+        if (DataController.USER_ID >= 0) {
+            stage.show();
+        }
     }
 
     public static void main(String[] args) {
diff --git a/client/app/src/main/java/main/MainController.java b/client/app/src/main/java/main/MainController.java
index 36f3aed..c7092a7 100644
--- a/client/app/src/main/java/main/MainController.java
+++ b/client/app/src/main/java/main/MainController.java
@@ -65,12 +65,35 @@ public class MainController {
         }
     }
 
+    @FXML
+    protected void onBackClick() {
+        weekOffset--;
+        setDates();
+        updateEvents();
+    }
+
+    @FXML
+    protected void onTodayClick() {
+        weekOffset = 0;
+        setDates();
+        updateEvents();
+    }
+
+    @FXML
+    protected void onNextClick() {
+        weekOffset++;
+        setDates();
+        updateEvents();
+    }
+
     @FXML
     protected void onAddBtnClick() {
         try {
-            FXMLLoader fxmlLoader = new FXMLLoader(MainApplication.class.getResource("create-event.fxml"));
-            Scene scene = new Scene(fxmlLoader.load(), 650, 500);
-            scene.getStylesheets().add(Objects.requireNonNull(MainApplication.class.getResource("create-event.css")).toExternalForm());
+            FXMLLoader fxmlLoader = new FXMLLoader(
+                    MainApplication.class.getResource("create-event.fxml"));
+            Scene scene = new Scene(fxmlLoader.load(), 650, 650);
+            scene.getStylesheets().add(Objects.requireNonNull(
+                    MainApplication.class.getResource("create-event.css")).toExternalForm());
             Stage stage = new Stage();
             stage.setTitle("Termin erstellen");
             stage.setScene(scene);
@@ -161,7 +184,8 @@ public class MainController {
 
         LocalDateTime eventDate = event.getDate();
 
-        int day = (int) Duration.between(weekStartDateTime.toLocalDate().atStartOfDay(), eventDate.toLocalDate().atStartOfDay()).toDays();
+        int day = (int) Duration.between(
+                weekStartDateTime.toLocalDate().atStartOfDay(), eventDate.toLocalDate().atStartOfDay()).toDays();
 
         if (day >= 0 && day < 7) {
             dayVBoxes[day].getChildren().add(vBox);
diff --git a/client/app/src/main/java/users/LoginControler.java b/client/app/src/main/java/users/LoginControler.java
deleted file mode 100644
index df20ac2..0000000
--- a/client/app/src/main/java/users/LoginControler.java
+++ /dev/null
@@ -1,4 +0,0 @@
-package users;
-
-public class LoginControler {
-}
diff --git a/client/app/src/main/java/users/LoginController.java b/client/app/src/main/java/users/LoginController.java
new file mode 100644
index 0000000..0350460
--- /dev/null
+++ b/client/app/src/main/java/users/LoginController.java
@@ -0,0 +1,50 @@
+package users;
+
+import javafx.event.ActionEvent;
+import javafx.fxml.FXML;
+import javafx.scene.Node;
+import javafx.scene.control.Label;
+import javafx.scene.control.TextField;
+import javafx.stage.Stage;
+import res.DataController;
+
+public class LoginController {
+    @FXML
+    public TextField userField;
+    @FXML
+    public TextField passField;
+    @FXML
+    public Label userErrLabel;
+    @FXML
+    public Label passErrLabel;
+
+    @FXML
+    protected void login(ActionEvent event) {
+        if (userField.getText().trim().isEmpty()) {
+            userErrLabel.setText("Bitte Usernamen eingeben!");
+            passErrLabel.setText("");
+            return;
+        }
+        if (passField.getText().trim().isEmpty()) {
+            userErrLabel.setText("");
+            passErrLabel.setText("Bitte Passwort eingeben!");
+            return;
+        }
+
+        DataController dataController = new DataController();
+        if (!dataController.login(userField.getText(), passField.getText())) {
+            userErrLabel.setText("Name und Passwort passen nicht zueinander!");
+            passErrLabel.setText("Name und Passwort passen nicht zueinander!");
+            return;
+        }
+
+        Stage stage = (Stage) ((Node) event.getSource()).getScene().getWindow();
+        stage.close();
+    }
+
+    @FXML
+    protected void abortBtnClick(ActionEvent event) {
+        Stage stage = (Stage) ((Node) event.getSource()).getScene().getWindow();
+        stage.close();
+    }
+}
diff --git a/client/app/src/main/resources/main/create-event.css b/client/app/src/main/resources/main/create-event.css
index 59602e9..442c669 100644
--- a/client/app/src/main/resources/main/create-event.css
+++ b/client/app/src/main/resources/main/create-event.css
@@ -32,4 +32,15 @@ Label{
 
 .mainButton{
     -fx-font-weight: bold;
+}
+
+#labelError{
+    -fx-font-weight: bold;
+    -fx-max-width: 1000px;
+    -fx-text-fill: #ff5555;
+    -fx-padding: 16px;
+    -fx-min-height: 140px;
+    -fx-max-height: 400px;
+    -fx-wrap-text: true;
+    -fx-font-size: 16px;
 }
\ No newline at end of file
diff --git a/client/app/src/main/resources/main/create-event.fxml b/client/app/src/main/resources/main/create-event.fxml
index 2ca5917..c56066c 100644
--- a/client/app/src/main/resources/main/create-event.fxml
+++ b/client/app/src/main/resources/main/create-event.fxml
@@ -5,7 +5,8 @@
 
 <?import javafx.collections.FXCollections?>
 <?import java.lang.String?>
-<GridPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml/1" fx:controller="main.CreateEventController">
+<GridPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml/1"
+          fx:controller="main.CreateEventController">
 
     <columnConstraints>
         <ColumnConstraints/>
@@ -13,15 +14,16 @@
         <ColumnConstraints/>
     </columnConstraints>
     <rowConstraints>
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
-        <RowConstraints vgrow="ALWAYS" />
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
     </rowConstraints>
 
     <Label styleClass="mainLabel">Termin anlegen</Label>
@@ -43,17 +45,18 @@
     <ComboBox fx:id="ComboBoxPriotity" GridPane.columnIndex="1" GridPane.rowIndex="6" maxWidth="200" minWidth="200">
         <items>
             <FXCollections fx:factory="observableArrayList">
-                <String fx:value="gering" />
-                <String fx:value="mittel" />
-                <String fx:value="hoch" />
+                <String fx:value="gering"/>
+                <String fx:value="mittel"/>
+                <String fx:value="hoch"/>
             </FXCollections>
         </items>
     </ComboBox>
     <CheckBox fx:id="checkBoxIsFullDay" GridPane.columnIndex="1" GridPane.rowIndex="7"/>
     <CheckBox fx:id="checkBoxIsPrivate" GridPane.columnIndex="1" GridPane.rowIndex="8"/>
+    <Label fx:id="labelError" GridPane.columnIndex="1" GridPane.rowIndex="9"/>
 
-    <HBox GridPane.columnIndex="1" GridPane.rowIndex="9" GridPane.columnSpan="2"  alignment="CENTER_RIGHT">
-        <Button onAction="#abortBtnClick" maxWidth="150" minWidth="150" >Abbrechen</Button>
+    <HBox GridPane.columnIndex="1" GridPane.rowIndex="10" GridPane.columnSpan="2" alignment="CENTER_RIGHT">
+        <Button onAction="#abortBtnClick" maxWidth="150" minWidth="150">Abbrechen</Button>
         <Button styleClass="mainButton" onAction="#createBtnClick" maxWidth="150" minWidth="150">Anlegen</Button>
     </HBox>
 
diff --git a/client/app/src/main/resources/main/main-view.fxml b/client/app/src/main/resources/main/main-view.fxml
index b5bf7e2..aa1402c 100644
--- a/client/app/src/main/resources/main/main-view.fxml
+++ b/client/app/src/main/resources/main/main-view.fxml
@@ -5,15 +5,17 @@
 <?import javafx.scene.image.*?>
 <?import javafx.scene.layout.*?>
 
-<GridPane style="-fx-background-color: #424242;" xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml/1" fx:controller="main.MainController">
+<GridPane style="-fx-background-color: #424242;" xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml/1"
+          fx:controller="main.MainController">
     <columnConstraints>
-        <ColumnConstraints hgrow="NEVER" maxWidth="60.0" minWidth="60.0" />
-        <ColumnConstraints hgrow="ALWAYS" />
+        <ColumnConstraints hgrow="NEVER" maxWidth="60.0" minWidth="60.0"/>
+        <ColumnConstraints hgrow="ALWAYS"/>
     </columnConstraints>
     <rowConstraints>
-        <RowConstraints vgrow="SOMETIMES" />
+        <RowConstraints vgrow="SOMETIMES"/>
     </rowConstraints>
-    <VBox alignment="TOP_CENTER" prefHeight="200.0" prefWidth="100.0" spacing="5.0" style="-fx-background-color: #525E74;">
+    <VBox alignment="TOP_CENTER" prefHeight="200.0" prefWidth="100.0" spacing="5.0"
+          style="-fx-background-color: #525E74;">
         <ImageView fitHeight="50.0" fitWidth="50.0" pickOnBounds="true" preserveRatio="true">
 
         </ImageView>
@@ -29,33 +31,42 @@
     </VBox>
     <GridPane prefHeight="200.0" prefWidth="222.0" GridPane.columnIndex="1" GridPane.rowIndex="0">
         <columnConstraints>
-        <ColumnConstraints hgrow="ALWAYS" />
-         <ColumnConstraints />
+            <ColumnConstraints hgrow="ALWAYS"/>
+            <ColumnConstraints/>
+            <ColumnConstraints/>
+            <ColumnConstraints/>
+            <ColumnConstraints/>
         </columnConstraints>
         <rowConstraints>
-            <RowConstraints />
-            <RowConstraints vgrow="ALWAYS" />
+            <RowConstraints/>
+            <RowConstraints vgrow="ALWAYS"/>
         </rowConstraints>
-        <Label fx:id="LabelMonth" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" styleClass="labelMonth" textFill="WHITE" GridPane.columnIndex="0" GridPane.rowIndex="0">
+        <Label fx:id="LabelMonth" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308"
+               styleClass="labelMonth" textFill="WHITE" GridPane.columnIndex="0" GridPane.rowIndex="0">
             Monat
             <padding>
-                <Insets left="5" />
+                <Insets left="5"/>
             </padding>
         </Label>
+        <Button onAction="#onBackClick" GridPane.columnIndex="1" maxHeight="1.7976931348623157E308">zurück</Button>
+        <Button onAction="#onTodayClick" GridPane.columnIndex="2" maxHeight="1.7976931348623157E308">heute</Button>
+        <Button onAction="#onNextClick" GridPane.columnIndex="3" maxHeight="1.7976931348623157E308">weiter</Button>
 
-        <GridPane fx:id="calendarGrid" gridLinesVisible="true"  styleClass="gridCalendar" GridPane.columnIndex="0" GridPane.rowIndex="1">
+        <GridPane fx:id="calendarGrid" gridLinesVisible="true" styleClass="gridCalendar" GridPane.columnSpan="4"
+                  GridPane.columnIndex="0" GridPane.rowIndex="1">
             <columnConstraints>
-                <ColumnConstraints hgrow="ALWAYS" maxWidth="14.2857142857" minWidth="14.2857142857" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
-                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857" />
+                <ColumnConstraints hgrow="ALWAYS" maxWidth="14.2857142857" minWidth="14.2857142857"
+                                   percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
+                <ColumnConstraints hgrow="ALWAYS" percentWidth="14.2857142857"/>
             </columnConstraints>
             <rowConstraints>
-                <RowConstraints maxHeight="55.0" minHeight="25.0" vgrow="NEVER" />
-                <RowConstraints percentHeight="-Infinity" vgrow="ALWAYS" />
+                <RowConstraints maxHeight="55.0" minHeight="25.0" vgrow="NEVER"/>
+                <RowConstraints percentHeight="-Infinity" vgrow="ALWAYS"/>
             </rowConstraints>
 
         </GridPane>
diff --git a/client/app/src/main/resources/users/login.css b/client/app/src/main/resources/users/login.css
index e69de29..2efd649 100644
--- a/client/app/src/main/resources/users/login.css
+++ b/client/app/src/main/resources/users/login.css
@@ -0,0 +1,37 @@
+* {
+   -fx-base-background-color: #2B2D42;
+   -fx-base1-background-color: #525E74;
+
+   -fx-main-border-color: #B0B0B0;
+   -fx-main-text-color: #ffffff;
+}
+
+GridPane{
+    -fx-background-color: #3E415F;
+    -fx-padding: 20px;
+    -fx-font-size: 20px;
+    -fx-font-family: Segoe UI;
+
+    -fx-border-insets: 1;
+    -fx-border-color: #B0B0B0;
+    -fx-border-style: solid;
+    -fx-border-width: 2;
+    -fx-effect: dropshadow(three-pass-box, rgba(100, 100, 100, 1), 24, 0.5, 0, 0);
+}
+
+Label{
+    -fx-text-fill: white;
+    -fx-max-width: 150px;
+    -fx-min-width: 150px;
+}
+
+.errorLbl{
+    -fx-font-weight: bold;
+        -fx-max-width: 200px;
+        -fx-text-fill: #ff5555;
+        -fx-padding: 16px;
+        -fx-min-height: 140px;
+        -fx-max-height: 400px;
+        -fx-wrap-text: true;
+        -fx-font-size: 16px;
+}
\ No newline at end of file
diff --git a/client/app/src/main/resources/users/login.fxml b/client/app/src/main/resources/users/login.fxml
index 25a9267..1eddceb 100644
--- a/client/app/src/main/resources/users/login.fxml
+++ b/client/app/src/main/resources/users/login.fxml
@@ -1,11 +1,32 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<?import java.lang.*?>
-<?import java.util.*?>
-<?import javafx.scene.*?>
 <?import javafx.scene.control.*?>
 <?import javafx.scene.layout.*?>
+<GridPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml" fx:controller="users.LoginController">
 
-<GridPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml"  fx:controller="users.LoginControler">
+    <columnConstraints>
+        <ColumnConstraints/>
+        <ColumnConstraints/>
+        <ColumnConstraints/>
+    </columnConstraints>
+    <rowConstraints>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+        <RowConstraints vgrow="ALWAYS"/>
+    </rowConstraints>
+
+    <Label GridPane.columnIndex="1">Anmelden</Label>
+
+    <Label GridPane.rowIndex="1">Username</Label>
+    <TextField GridPane.columnIndex="1" GridPane.rowIndex="1" fx:id="userField"/>
+    <Label styleClass="errorLbl" GridPane.columnIndex="2" GridPane.rowIndex="1" fx:id="userErrLabel"/>
+
+    <Label GridPane.rowIndex="2">Paswort</Label>
+    <PasswordField GridPane.columnIndex="1" GridPane.rowIndex="2" fx:id="passField"/>
+    <Label styleClass="errorLbl" GridPane.columnIndex="2" GridPane.rowIndex="2" fx:id="passErrLabel"/>
+
+    <Button onAction="#abortBtnClick" GridPane.columnIndex="1" GridPane.rowIndex="3">Beenden</Button>
+    <Button onAction="#login" GridPane.columnIndex="2" GridPane.rowIndex="3">Anmelden</Button>
 
 </GridPane>
diff --git a/client/data/src/main/java/res/DataController.java b/client/data/src/main/java/res/DataController.java
index ddc826d..3492acd 100644
--- a/client/data/src/main/java/res/DataController.java
+++ b/client/data/src/main/java/res/DataController.java
@@ -14,26 +14,43 @@ import java.util.*;
 
 public class DataController {
 
+    public static long USER_ID = -1;
+
     private static final String ALL_EVENTS_ENDPOINT = "http://localhost:8080/vpr/all-events";
     private static final String ALL_USERS_ENDPOINT = "http://localhost:8080/vpr/all-users";
     private static final String ADD_EVENT_ENDPOINT = "http://localhost:8080/vpr/add-event";
     private static final String DELETE_EVENT_ENDPOINT = "http://localhost:8080/vpr/del-event";
+    private static final String LOGIN_ENDPOINT = "http://localhost:8080/vpr/login";
 
     private final HttpRequest httpRequest;
 
-    public DataController(){
+    public DataController() {
         httpRequest = new HttpRequest();
     }
 
-    public void createEvent(Event event){
+    public boolean login(String username, String password) {
+        try {
+            USER_ID = Long.parseLong(httpRequest.sendPostRequest(
+                    LOGIN_ENDPOINT,
+                    "login=" + username
+                            + "&password=" + password
+            ));
+        } catch (Exception e) {
+            e.printStackTrace();
+            return false;
+        }
+        return USER_ID >= 0;
+    }
+
+    public void createEvent(Event event) {
         try {
             System.out.println(httpRequest.sendPostRequest(ADD_EVENT_ENDPOINT, event.getAsUrlParam()));
         } catch (Exception e) {
-            e.printStackTrace();
+            throw new RuntimeException("Es konnte keine Verbindung mit dem Server hergestellt werden.");
         }
     }
 
-    public void deleteEvent(int eventId){
+    public void deleteEvent(int eventId) {
         try {
             System.out.println(httpRequest.sendPostRequest(DELETE_EVENT_ENDPOINT, "eventId=" + eventId));
         } catch (Exception e) {
@@ -45,16 +62,16 @@ public class DataController {
         ArrayList<Event> eventList = new ArrayList<>();
 
         try {
-            String jsonResponse = httpRequest.sendPostRequest(ALL_EVENTS_ENDPOINT, "userId=1");
+            String jsonResponse = httpRequest.sendPostRequest(ALL_EVENTS_ENDPOINT, "userId=" + USER_ID);
             System.out.println(jsonResponse);
 
             ObjectMapper objectMapper = new ObjectMapper();
             //String json = "{ \"color\" : \"Black\", \"type\" : \"BMW\" }";
 
-            for (Object obj : objectMapper.readValue(jsonResponse, Object[].class)){
+            for (Object obj : objectMapper.readValue(jsonResponse, Object[].class)) {
                 ArrayList<Object> list = new ArrayList<>();
                 if (obj.getClass().isArray()) {
-                    list = (ArrayList<Object>) Arrays.asList((Object[])obj);
+                    list = (ArrayList<Object>) Arrays.asList((Object[]) obj);
                 } else if (obj instanceof Collection) {
                     list = new ArrayList<>((Collection<?>) obj);
                 }
diff --git a/client/data/src/main/java/res/Event.java b/client/data/src/main/java/res/Event.java
index 33ee93f..54ac5e5 100644
--- a/client/data/src/main/java/res/Event.java
+++ b/client/data/src/main/java/res/Event.java
@@ -2,9 +2,14 @@ package res;
 
 import com.sun.jdi.event.StepEvent;
 
+import java.time.Duration;
+import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
 
 public class Event {
 
@@ -61,7 +66,24 @@ public class Event {
                  String end,
                  LocalDateTime date,
                  int ownerId
-    ) {
+    ) throws IllegalArgumentException {
+        if (name.length() < 3) {
+            throw new IllegalArgumentException("Der Name muss eine L\u00e4nge von 3 haben.");
+        }
+        Pattern pattern = Pattern.compile("[A-Za-zÄÖÜäöü0-9 =!?+*/$%€.:,;_<>()-]*");
+        Matcher matcher = pattern.matcher(name);
+        if (!matcher.matches()) {
+            throw new IllegalArgumentException("Der Name Darf nur aus Zahlen, Buchstaben und " +
+                    "folgenden Sonderzeichen bestehen: =!?+*/$%€.:,;_ <>()-");
+        }
+        if (priority < 0) {
+            throw new IllegalArgumentException("Bitte eine Priorit\u00e4t w\u00e4hlen.");
+        }
+        LocalDateTime today = LocalDateTime.now().toLocalDate().atStartOfDay();
+        if (Duration.between(today, date).isNegative()) {
+            throw new IllegalArgumentException("Das Datum muss in der Zukunft liegen.");
+        }
+
         this.name = name;
         this.priority = priority;
         this.isFullDay = isFullDay;
diff --git a/client/data/src/main/java/res/HttpRequest.java b/client/data/src/main/java/res/HttpRequest.java
index 183efb8..c565e31 100644
--- a/client/data/src/main/java/res/HttpRequest.java
+++ b/client/data/src/main/java/res/HttpRequest.java
@@ -9,7 +9,7 @@ import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 
 public class HttpRequest {
-    public String sendPostRequest(String urlString, String urlParameters) throws Exception{
+    public String sendPostRequest(String urlString, String urlParameters) throws Exception {
         byte[] postData = urlParameters.getBytes(StandardCharsets.UTF_8);
         int postDataLength = postData.length;
 
@@ -46,7 +46,7 @@ public class HttpRequest {
         }
     }
 
-    public String sendGetRequest(String urlString) throws Exception{
+    public String sendGetRequest(String urlString) throws Exception {
         URL url = new URL(urlString);
         HttpURLConnection con = (HttpURLConnection) url.openConnection();
         con.setRequestMethod("GET");