by Tuan Tuong Dang @ Multincwith guidance from Huy Zing

BarCamp Saigon 1November 15, 2008

echo-o

“simple real-time feedback”

From:

To:

echo-o architecture

Web Application

Multiple clients:Web browserAdobe AIRiPhone mobileAndroid mobile

Android Mobile

This presentation

Structure of an Android application

Building blocks of an Android application

User Interface of the echo-o application

HelloWorld.java

public class HelloWorld extends Activity { public void onCreate(Bundle

instanceState) { super.onCreate(instanceState); TextView tv = new TextView(this); tv.setText("Hello World!!!"); this.setContentView(tv); }}

4 Android Building Blocks

Activity

Service

BroadcastReceiver

ContentProvider

Building Blocks for echo-o

Activity – to show screens and respond to user

Service – to create a re-usable sound object

BroadcastReceiver

ContentProvider

Other APIs

Intent

Views

Notifications

Other APIs for echo-o

Intent – messages such as invoking a sound

Views – display web pages

Notifications – send vibrate notifications

UI ScreensEach screen has views

ViewGroup

ViewGroup View

View ViewView

role_name [1:1] role_name [1:1]

role_name [1:1]

role_name [1:1]

role_name [1:1]

View LayoutsFrameLayout

LinearLayout

RelativeLayout

TableLayout

AbsoluteLayout

View ComponentsButton

TextView

WebView – displays our web application

EditText

ListView

CheckBox

Radio

WebViewProblem: JavaScript is disabled by default.

Solution: browser.getSettings().setJavaScriptEnabled(true);

WebViewProblem: Communication between Android app and web

app:

Solutions:

Set up handler for JavaScript alerts/prompt/confirms:browser.setWebChromeClient(new WebChromeConfirm());private class WebChromeConfirm extends WebChromeClient {…}

Web app invokes method on native app: MainActivity.java

AndroidManipulation am = new AndroidManipulation(this);browser.addJavascriptInterface(am, “am");

WebApp.js:am. doVibrate();

WebViewProblem: Zoom picker is disabled by default

Solution:LinearLayout zoomLayout =

(LinearLayout)findViewById(R.id.basic_map_zoom); settingWebView();View zc = browser.getZoomControls();zoomLayout.addView(zc, new

ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT , ViewGroup.LayoutParams.WRAP_CONTENT ));

WebViewProblem: clicking links are sent to system web browser.

Solution: clicking links stay in the WebView

browser.setWebViewClient(new Callback());private class Callback extends WebViewClient{

public boolean shouldOverrideUrlLoading(WebView view, String url) {loadUrl(url);return(true);

}}

WebViewProblem: changing orientation resets emulator

Solution:a) test on real mobile device

b) on emulator:

protected void onSaveInstanceState(Bundle outState) {super.onSaveInstanceState(outState);outState.putString("address", txt.getText().toString());

}....String address = savedInstanceState != null ?

savedInstanceState.getString("address") : "http://www.google.com.vn";loadUrl(address);

http://multinc.com/http://code.google.com/android/