[ADD] all classes and packages according to class diagram

app/src/main/java/com/a1/nextlocation/MainActivity.java

@@ -0,0 +1,20 @@
+package com.a1.nextlocation;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.os.Bundle;
+
+import com.a1.nextlocation.R;
+
+public class MainActivity extends AppCompatActivity {
+
+    /**
+     * onCreate method that creates the main activity
+     * @param savedInstanceState the saved instance state of the app
+     */
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+    }
+}