added quick connect (if app run it will try to connect to last used device

app/src/main/java/de/jonasled/led_table/MainActivity.java

@@ -4,6 +4,7 @@ import androidx.appcompat.app.AppCompatActivity;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.AdapterView;
@@ -18,11 +19,15 @@ public class MainActivity extends AppCompatActivity {
     private ListView lstvw;
     private ArrayAdapter aAdapter;
     private BluetoothAdapter bAdapter;
+    private SharedPreferences preferences;
+    private SharedPreferences.Editor edit;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+        preferences = getSharedPreferences("settings", MODE_PRIVATE);
+        edit = preferences.edit();
         bAdapter = BluetoothAdapter.getDefaultAdapter();
         lstvw = (ListView) findViewById(R.id.deviceList);
         Set<BluetoothDevice> pairedDevices = bAdapter.getBondedDevices();
@@ -40,11 +45,18 @@ public class MainActivity extends AppCompatActivity {
                 aAdapter = new ArrayAdapter(getApplicationContext(), android.R.layout.simple_list_item_1, list);
                 lstvw.setAdapter(aAdapter);
             }
+
+            try{
+                openControlActivity(preferences.getString("MAC", ""));
+            } catch (Exception e) {}
+
         }
 
         lstvw.setOnItemClickListener(new AdapterView.OnItemClickListener(){
             @Override
             public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+                edit.putString("MAC", parent.getItemAtPosition(position).toString().split("MAC Address: ")[1]);
+                edit.commit();
                 openControlActivity(parent.getItemAtPosition(position).toString().split("MAC Address: ")[1]);
             }
         });