diff --git a/app/build.gradle b/app/build.gradle
index b17a93e..1c98d76 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -36,4 +36,5 @@ dependencies {
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.5'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
+    implementation "androidx.startup:startup-runtime:1.1.1"
 }
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index cef8f3d..86c565d 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -2,6 +2,28 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+<!--    &lt;!&ndash; If your app targets Android 13 (API level 33)-->
+<!--         or higher, you must declare the NEARBY_WIFI_DEVICES permission. &ndash;&gt;-->
+<!--    <uses-permission android:name="android.permission.NEARBY_WIFI_DEVICES"-->
+<!--    &lt;!&ndash; If your app derives location information from Wi-Fi APIs,-->
+<!--         don't include the "usesPermissionFlags" attribute. &ndash;&gt;-->
+<!--        android:usesPermissionFlags="neverForLocation" />-->
+
+    <uses-permission
+        android:required="true"
+        android:name="android.permission.ACCESS_FINE_LOCATION"/>
+    <!-- If any feature in your app relies on precise location information,
+         don't include the "maxSdkVersion" attribute. -->
+    <uses-permission
+        android:required="true"
+        android:name="android.permission.ACCESS_WIFI_STATE"/>
+    <uses-permission
+        android:required="true"
+        android:name="android.permission.CHANGE_WIFI_STATE"/>
+    <uses-permission
+        android:required="true"
+        android:name="android.permission.INTERNET"/>
+
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
diff --git a/app/src/main/java/de/oklein/android/ueberwachungssystem/Logger/Logger.java b/app/src/main/java/de/oklein/android/ueberwachungssystem/Logger/Logger.java
new file mode 100644
index 0000000..314af68
--- /dev/null
+++ b/app/src/main/java/de/oklein/android/ueberwachungssystem/Logger/Logger.java
@@ -0,0 +1,44 @@
+package de.oklein.android.ueberwachungssystem.Logger;
+
+import android.util.Log;
+import android.widget.TextView;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+public class Logger {
+    private TextView textView;
+    private StringBuffer sb = new StringBuffer();
+    private String tag;
+
+    public Logger(String tag, TextView textView, String logInitText)  {
+        this.tag = tag;
+        this.textView = textView;
+        sb.append(logInitText);
+    }
+
+    public void log(String s)  {
+        Log.d(tag, s);
+        sb.append(s).append("\n");
+        if (textView != null) {
+            textView.setText(sb.toString());
+        }
+    }
+
+    public void log(Exception e)  {
+        StringWriter sw = new StringWriter();
+        e.printStackTrace(new PrintWriter(sw));
+        log(sw.toString());
+    }
+
+    public void clearLog()  {
+        sb.setLength(0);
+        if (textView != null) {
+            textView.setText("");
+        }
+    }
+
+    public String getLoggedText()  {
+        return sb.toString();
+    }
+}
diff --git a/app/src/main/java/de/oklein/android/ueberwachungssystem/MainActivity.java b/app/src/main/java/de/oklein/android/ueberwachungssystem/MainActivity.java
index 6bf3046..2c9d0d6 100644
--- a/app/src/main/java/de/oklein/android/ueberwachungssystem/MainActivity.java
+++ b/app/src/main/java/de/oklein/android/ueberwachungssystem/MainActivity.java
@@ -1,15 +1,125 @@
 package de.oklein.android.ueberwachungssystem;
 
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentTransaction;
 import androidx.appcompat.app.AppCompatActivity;
 
 import android.os.Bundle;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.ListView;
+import android.widget.TextView;
+
 
 public class MainActivity extends AppCompatActivity {
-
+    private Fragment aktuellesFragment;
+    private void log(String nachricht) {
+        Log.d(this.getClass().getSimpleName(), nachricht);
+    }
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        setTitle( this.getClass().getSimpleName());
         setContentView(R.layout.activity_main);
-        //penis
+    }
+    public void onClickZeigeFragment1(View view) {
+        Button button = (Button) view;
+        log(button.getText() + " ausgewählt");
+        zeigeFragment(Fragment1.erstellen("Fragment 1 wurde angeklickt"));
+    }
+    public void onClickZeigeFragment2(View view) {
+        Button button = (Button) view;
+        log(button.getText() + " ausgewählt");
+        zeigeFragment(Fragment2.erstellen("Fragment 2 wurde angeklickt"));
+    }
+
+    public void onClickEntferneFragment(View view) {
+        entferneFragment();
+    }
+    private void zeigeFragment(Fragment fragment) {
+        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
+        ft.replace(R.id.frame, fragment);
+        ft.commit();
+        aktuellesFragment = fragment;
+    }
+    private void entferneFragment() {
+        if (aktuellesFragment != null) {
+            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
+            ft.remove(aktuellesFragment);
+            ft.commit();
+            aktuellesFragment = null ;
+        }
+    }
+    public static class Fragment1 extends Fragment {
+        private String text;
+        private final static String KEY_TEXT = "KEY_TEXT";
+
+        private void log(String nachricht) {
+            Log.d(this.getClass().getSimpleName(), nachricht);
+        }
+
+        @Override
+        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle bundle) {
+            log("onCreateView");
+            View view = inflater.inflate(R.layout.fragment1, container, false);
+            TextView textView = (TextView) view.findViewById(R.id.textView);
+            textView.setText(text);
+            return view;
+        }
+        public static Fragment1 erstellen(String text) {
+            Fragment1 fragment = new Fragment1();
+            Bundle b = new Bundle();
+            b.putString(KEY_TEXT, text);
+            fragment.setArguments(b);
+            return fragment;
+        }
+        @Override
+        public void onCreate(Bundle bundle) {
+            super .onCreate(bundle);
+            Bundle args = getArguments();
+            if (args != null ) {
+                text = args.getString(KEY_TEXT);
+                log("onCreate: text=" + text);
+            } else {
+                log("onCreate");
+            }
+        }
+    }
+    public static class Fragment2 extends Fragment {
+        private String text;
+        private final static String KEY_TEXT = "KEY_TEXT" ;
+        private void log(String nachricht) {
+            Log.d(this.getClass().getSimpleName(), nachricht);
+        }
+        @Override
+        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle bundle) {
+            log( "onCreateView" );
+            View view = inflater.inflate(R.layout.fragment2, container, false );
+            EditText editText = (EditText) view.findViewById(R.id.editText1);
+            editText.setText(text);
+            return view;
+        }
+        public static Fragment2 erstellen(String text) {
+            Fragment2 fragment = new Fragment2();
+            Bundle b = new Bundle();
+            b.putString(KEY_TEXT, text);
+            fragment.setArguments(b);
+            return fragment;
+        }
+        @Override
+        public void onCreate(Bundle bundle) {
+            super.onCreate(bundle);
+            Bundle args = getArguments();
+            if (args != null) {
+                text = args.getString(KEY_TEXT);
+                log("onCreate: text=" + text);
+            } else {
+                log("onCreate");
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 17eab17..6fa09dd 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -1,18 +1,44 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".MainActivity">
+    tools:context="de.oklein.android.ueberwachungssystem.MainActivity"
+    android:background="@android:color/holo_orange_light">
 
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+    <Button
+    android:id="@+id/button1"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_alignParentStart="true"
+    android:layout_alignParentTop="true"
+    android:text="Zeige Fragment 1"
+    android:onClick="onClickZeigeFragment1"/>
 
-</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
+    <Button
+    android:id="@+id/btnFordereRechte"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_alignParentStart="true"
+    android:layout_below="@+id/button1"
+    android:text="Zeige Fragment 2"
+    android:onClick="onClickZeigeFragment2"/>
+
+    <Button
+    android:id="@+id/buttonEntferneFragment"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_alignParentStart="true"
+    android:layout_below="@+id/btnFordereRechte"
+    android:text="Entferne Fragment"
+    android:onClick="onClickEntferneFragment"/>
+
+    <FrameLayout
+    android:id="@+id/frame"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:layout_alignParentStart="true"
+    android:layout_below="@+id/buttonEntferneFragment">
+    </FrameLayout>
+
+    </RelativeLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment1.xml b/app/src/main/res/layout/fragment1.xml
new file mode 100644
index 0000000..5336bc3
--- /dev/null
+++ b/app/src/main/res/layout/fragment1.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center_horizontal"
+    android:orientation="vertical"
+    android:background="@android:color/holo_green_light">
+
+    <TextView
+        android:id="@+id/textView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textAppearance="?android:attr/textAppearanceLarge"/>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/fragment2.xml b/app/src/main/res/layout/fragment2.xml
new file mode 100644
index 0000000..410b14e
--- /dev/null
+++ b/app/src/main/res/layout/fragment2.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center_horizontal"
+    android:orientation="vertical"
+    android:background="@android:color/holo_blue_light" >
+
+    <EditText
+        android:id="@+id/editText1"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:ems="10"
+        android:textStyle="italic"
+        android:inputType="textMultiLine" >
+        <requestFocus />
+    </EditText>
+
+</LinearLayout>
\ No newline at end of file