create a simple widget config activity

app/src/main/AndroidManifest.xml

@@ -29,6 +29,12 @@
                 android:name="android.appwidget.provider"
                 android:resource="@xml/widget_info"/>
         </receiver>
+
+        <activity android:name=".MyWidgetConfigure">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE"/>
+            </intent-filter>
+        </activity>
     </application>
 
 </manifest>

app/src/main/java/calculator/simplemobiletools/com/simple_calculator/MyWidgetConfigure.java

@@ -0,0 +1,39 @@
+package calculator.simplemobiletools.com.simple_calculator;
+
+import android.app.Activity;
+import android.appwidget.AppWidgetManager;
+import android.content.Intent;
+import android.os.Bundle;
+
+import butterknife.ButterKnife;
+import butterknife.OnClick;
+
+public class MyWidgetConfigure extends Activity {
+    private int widgetId;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.widget_config);
+        ButterKnife.bind(this);
+
+        final Intent intent = getIntent();
+        final Bundle extras = intent.getExtras();
+        if (extras != null) {
+            widgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);
+        }
+
+        if (widgetId == AppWidgetManager.INVALID_APPWIDGET_ID)
+            finish();
+
+        setResult(RESULT_CANCELED);
+    }
+
+    @OnClick(R.id.config_save)
+    public void saveConfig() {
+        final Intent resultValue = new Intent();
+        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, widgetId);
+        setResult(RESULT_OK, resultValue);
+        finish();
+    }
+}

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

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:padding="@dimen/activity_margin">
+
+    <Button
+        android:id="@+id/config_save"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Save"/>
+</RelativeLayout>

app/src/main/res/xml/widget_info.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
+                    android:configure="calculator.simplemobiletools.com.simple_calculator.MyWidgetConfigure"
                     android:initialLayout="@layout/activity_main"
                     android:minHeight="250dp"
                     android:minWidth="250dp">