Add back button.

Author: CDrummond

android/app/src/main/java/org/lyrion/squeezelite/SettingsActivity.java

@@ -4,18 +4,23 @@
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
 import android.content.Context;
+import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
+import android.graphics.drawable.ColorDrawable;
 import android.os.Build;
 import android.os.Bundle;
 import android.text.InputType;
+import android.view.Menu;
+import android.view.MenuItem;
 import android.widget.ArrayAdapter;
 import android.widget.EditText;
 import android.widget.LinearLayout;
 import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.RequiresPermission;
+import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
@@ -57,6 +62,20 @@ protected void onCreate(Bundle savedInstanceState) {
                 .beginTransaction()
                 .replace(R.id.settings, fragment)
                 .commit();
+        ActionBar actionBar = getSupportActionBar();
+        if (actionBar != null) {
+            actionBar.setDisplayHomeAsUpEnabled(true);
+            actionBar.setBackgroundDrawable(new ColorDrawable(ContextCompat.getColor(this, R.color.colorBackground)))   ;
+        }
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == android.R.id.home) {
+            onBackPressed();
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
     }
 
     public static class SettingsFragment extends PreferenceFragmentCompat implements SharedPreferences.OnSharedPreferenceChangeListener {