Added Activities to MainActivity and made them accessible

app/src/main/AndroidManifest.xml

         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.GreenWatch">
+        <activity
+            android:name=".ConnectionActivity"
+            android:exported="false" />
+        <activity
+            android:name=".VideodetectionAndAccelerometerActivity"
+            android:exported="false" />
+        <activity
+            android:name=".AudiodetectionAndAccelerometerActivity"
+            android:exported="false" />
+        <activity
+            android:name=".VideodetectionActivity"
+            android:exported="false" />
+        <activity
+            android:name=".AudiodetectionActivity"
+            android:exported="false" />
+        <activity
+            android:name=".AccelerometerActivity"
+            android:exported="false" />
         <activity
             android:name=".MainActivity"
             android:exported="true">

app/src/main/java/com/example/greenwatch/MainActivity.java

 
 import androidx.appcompat.app.AppCompatActivity;
 
+import android.content.Intent;
 import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
 
 public class MainActivity extends AppCompatActivity {
 
+    private Button audiodetectionButton;
+    private Button videodetectionButton;
+    private Button accelerometerButton;
+    private Button audiodetectionAndAccelerometerButton;
+    private Button videodetectionAndAccelerometerButton;
+    private Button connectionButton;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+
+        audiodetectionButton = (Button) findViewById(R.id.audiodetectionButton);
+        videodetectionButton = (Button) findViewById(R.id.videodetectionButton);
+        accelerometerButton = (Button) findViewById(R.id.accelerometerButton);
+        audiodetectionAndAccelerometerButton = (Button) findViewById(R.id.audiodetectionAndAccelerometerButton);
+        videodetectionAndAccelerometerButton = (Button) findViewById(R.id.videodetectionAndAccelerometerButton);
+        connectionButton = (Button) findViewById(R.id.connectionButton);
+        audiodetectionButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openAudiodetectionActivity();
+            }
+        });
+        videodetectionButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openVideodetectionActivity();
+            }
+        });
+        accelerometerButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openAccelerometerActivity();
+            }
+        });
+        audiodetectionAndAccelerometerButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openAudiodetectionAndAccelerometerActivity();
+            }
+        });
+        videodetectionAndAccelerometerButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openVideodetectionAndAccelerometerActivity();
+            }
+        });
+        connectionButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                openConnectionActivity();
+            }
+        });
+    }
+    public void openAudiodetectionActivity(){
+        Intent intent = new Intent(this, AudiodetectionActivity.class);
+        startActivity(intent);
+    }
+    public void openVideodetectionActivity(){
+        Intent intent =  new Intent(this, VideodetectionActivity.class);
+        startActivity(intent);
+    }
+    public void openAccelerometerActivity(){
+        Intent intent = new Intent(this, AccelerometerActivity.class);
+        startActivity(intent);
     }
+    public void openAudiodetectionAndAccelerometerActivity(){
+        Intent intent = new Intent(this, AudiodetectionAndAccelerometerActivity.class);
+        startActivity(intent);
+    }
+    public void openVideodetectionAndAccelerometerActivity(){
+        Intent intent = new Intent(this, VideodetectionAndAccelerometerActivity.class);
+        startActivity(intent);
+    }
+    public void openConnectionActivity(){
+        Intent intent = new Intent(this, ConnectionActivity.class);
+        startActivity(intent);
+    }
+
 }

app/src/main/res/layout/activity_main.xml

 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:padding="10dp"
     tools:context=".MainActivity">
 
     <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
+        android:id="@+id/tvStatusmessage"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
         android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        android:layout_weight="1">
+    </TextView>
+    
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical"
+        android:layout_weight="1">
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+        <Button
+            android:id="@+id/audiodetectionButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Audiodetection">
+        </Button>
+
+        <Button
+            android:id="@+id/videodetectionButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Videodetection">
+        </Button>
+
+        <Button
+            android:id="@+id/accelerometerButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Accelerometer">
+        </Button>
+
+        <Button
+            android:id="@+id/audiodetectionAndAccelerometerButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Audiodetection + Accelerometer">
+        </Button>
+
+        <Button
+            android:id="@+id/videodetectionAndAccelerometerButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Videodetection + Accelerometer">
+        </Button>
+
+        <Button
+            android:id="@+id/connectionButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Connect to Devices">
+        </Button>
+
+    </LinearLayout>
+
+</LinearLayout>