add an Invite friends button

app/src/main/java/com/simplemobiletools/calculator/activities/AboutActivity.java

@@ -60,13 +60,24 @@ public class AboutActivity extends SimpleActivity {
         }
     }
 
+    @OnClick(R.id.about_invite)
+    public void inviteFriend() {
+        final Intent intent = new Intent();
+        final String text = String.format(getString(R.string.share_text), getString(R.string.app_name), getStoreUrl());
+        intent.setAction(Intent.ACTION_SEND);
+        intent.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.app_name));
+        intent.putExtra(Intent.EXTRA_TEXT, text);
+        intent.setType("text/plain");
+        startActivity(Intent.createChooser(intent, getString(R.string.invite_via)));
+    }
+
     @OnClick(R.id.about_rate_us)
     public void rateUsClicked() {
         final Uri uri = Uri.parse("market://details?id=" + getPackageName());
         try {
             startActivity(new Intent(Intent.ACTION_VIEW, uri));
         } catch (ActivityNotFoundException ignored) {
-            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("http://play.google.com/store/apps/details?id=" + getPackageName())));
+            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(getStoreUrl())));
         }
     }
 
@@ -92,4 +103,8 @@ public class AboutActivity extends SimpleActivity {
         final String link = "https://plus.google.com/communities/104880861558693868382";
         startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(link)));
     }
+
+    private String getStoreUrl() {
+        return "https://play.google.com/store/apps/details?id=" + getPackageName();
+    }
 }

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

@@ -38,12 +38,22 @@
             android:text="@string/email"/>
 
         <TextView
-            android:id="@+id/about_rate_us"
+            android:id="@+id/about_invite"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_below="@+id/about_email"
             android:paddingBottom="@dimen/activity_margin"
             android:paddingTop="@dimen/activity_margin"
+            android:text="@string/invite_friends_underlined"
+            android:textColor="@color/colorPrimary"/>
+
+        <TextView
+            android:id="@+id/about_rate_us"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_below="@+id/about_invite"
+            android:paddingBottom="@dimen/activity_margin"
+            android:paddingTop="@dimen/activity_margin"
             android:text="@string/rate_us_underlined"
             android:textColor="@color/colorPrimary"/>
 

app/src/main/res/values-it/strings.xml

@@ -7,6 +7,9 @@
     <string name="website">Altre semplici app e codici sorgenti in:\nhttp://simplemobiletools.com</string>
     <string name="email_label">Invia la tua opinione o i tuoi suggerimenti a:</string>
     <string name="third_party_licences_underlined"><u>Licenze di terze parti</u></string>
+    <string name="invite_friends_underlined"><u>Invite friends</u></string>
+    <string name="share_text">Hey, come check out %1$s at %2$s</string>
+    <string name="invite_via">Invite via</string>
     <string name="rate_us_underlined"><u>Dacci un voto sul Play Store</u></string>
     <string name="follow_us">Seguici:</string>
     <string name="copyright">v %1$s\nCopyright © Simple Mobile Tools %2$d</string>

app/src/main/res/values-ja/strings.xml

@@ -7,6 +7,9 @@
     <string name="website">もっとシンプルなアプリとソースコードは:\nhttp://simplemobiletools.com</string>
     <string name="email_label">ご意見やご提案をお送りください:</string>
     <string name="third_party_licences_underlined"><u>サードパーティー ライセンス</u></string>
+    <string name="invite_friends_underlined"><u>Invite friends</u></string>
+    <string name="share_text">Hey, come check out %1$s at %2$s</string>
+    <string name="invite_via">Invite via</string>
     <string name="rate_us_underlined"><u>Play ストアで評価してください</u></string>
     <string name="follow_us">フォローしてください:</string>
     <string name="copyright">v %1$s\nCopyright © Simple Mobile Tools %2$d</string>

app/src/main/res/values-sv/strings.xml

@@ -7,6 +7,9 @@
     <string name="website">Fler enkla appar och källkod här:\nhttp://simplemobiletools.com</string>
     <string name="email_label">Skicka feedback och förslag till:</string>
     <string name="third_party_licences_underlined"><u>Tredjepartslicenser</u></string>
+    <string name="invite_friends_underlined"><u>Invite friends</u></string>
+    <string name="share_text">Hey, come check out %1$s at %2$s</string>
+    <string name="invite_via">Invite via</string>
     <string name="rate_us_underlined"><u>Betygsätt oss i Play Butiken</u></string>
     <string name="follow_us">Följ oss:</string>
     <string name="copyright">v %1$s\nCopyright © Simple Mobile Tools %2$d</string>

app/src/main/res/values/strings.xml

@@ -8,6 +8,9 @@
     <string name="email_label">Send your feedback or suggestions to:</string>
     <string name="email" translatable="false">hello@simplemobiletools.com</string>
     <string name="third_party_licences_underlined"><u>Third party licences</u></string>
+    <string name="invite_friends_underlined"><u>Invite friends</u></string>
+    <string name="share_text">Hey, come check out %1$s at %2$s</string>
+    <string name="invite_via">Invite via</string>
     <string name="rate_us_underlined"><u>Rate us in the Play Store</u></string>
     <string name="follow_us">Follow us:</string>
     <string name="copyright">v %1$s\nCopyright © Simple Mobile Tools %2$d</string>