Overview. Lecture: Implicit Calling via Share Implicit Receiving via Share Launch Telephone Launch Settings Homework

Transcription

1 Implicit Intents

2 Overview Lecture: Implicit Calling via Share Implicit Receiving via Share Launch Telephone Launch Settings Homework

3 Intents Intent asynchronous message used to activate one Android component using another Intent - A Task that is to be performed Triggers the OS that something has occurred and an action needs to be taken The OS, based on the data received, determines the receiver for the intent Implicit Trigger general components of a category through Android OS (OS decides / user chooses)

4 Implicit Intents Implicit Intents - do not directly specify the Android component to be activated Only specify the action to be performed We will create an activity with several buttons to try our implicit intents Each button will fire-off a different intent ACTION

5 Intents and the Manifest The manifest can have Intent Filters Require some conditions to be fulfilled to process the intent Information about the data and category of the Intent Identities the behavior of an Android Intent

6 Parts of an Intent 1. Component What component can safetly handle the intent: 1. CATEGORY_LAUNCHER 2. CATEGORY_BROWSER 2. Actions What the intent will cause: 1. ACTION_CALL 2. ACTION_BATTERY_LOW 3. ACTION_SCREEN_ON 3. Data Assists the action where information is necessary, such as the phone number to dial 4. Extras key-value pairs for when additional data is needed to fulfill the task

7 Example Intent Rolls Wi-Fi & Bluetooth Ability to change the wi-fi / Bluetooth connection while inside the application Camera Opening the camera app and receiving image data back GPS Sensor Extraction of current location of the user (if they let you) SMS/MMS Sending messages through native applications Time Zone changes

8 Implicit Intents - Actions Some common intent actions: Activity 2 activity data transfer View a website Launch Telephone with number Work with Contacts Use Camera Work with Calendar or Alarm Clock Text Message Create a Note Play Media Show a location on a Map Compose an Connect with Wi-Fi / Bluetooth And more

9 Side Note - Service Services perform specific tasks in the background They don t have a UI & run on the main thread of the app They run in the background even when another app is visible Great for IPC, networking, music, file I/O We can start and stop services using explicit intents We ll get back to Services later

10 Implicit Intents Sharing Text Create a new project Implicit Intents Add several buttons to launch other activities/intents We will share content to other apps that support Text/Plain data This is done through the intent constructor: Intent intent = new Intent(Intent.ACTION_SEND);

11 Implicit Intents - Sharing Create activity (ShareIntentActivity) Create a layout with a plain text edit field Add a button with the text share We don t need any special permission in the manifest since we will be sending out a share intent If we wanted our app to respond to share intents, we d need to modify the manifest

12 Implicit Intents - Sharing Open the activity code Grab the edit text and button reference Create an anonymous onclicklistener for the button Grab the edit text using: String msg = edittext.gettext().tostring();

13 Implicit Intents - Sharing Button button; EditText protected void oncreate(bundle savedinstancestate){ super.oncreate(savedinstancestate); setcontentview(r.layout.activity_share_intent); button = (Button)findViewById(R.id.button_share); edittext = (EditText)findViewById(R.id.editText_share); button.setonclicklistener(new public void onclick(view v) { String message = edittext.gettext().tostring(); //continued code }});}

14 Implicit Intents - Sharing Using the Intent Action ACTION_SEND we can send information out of our application to other compatible applications We send data by specifying the data type, in this case text/plain If we only pass the intent, Android may automatically run the application that is compatible We can force the chooser and provide a title But what if there are no apps to respond?

15 Implicit Intents No Apps to Respond? If there are no apps to run the intent, our app will CRASH! Verify an app exists by calling: intent.resolveactivity(pm) If the result!= null, we are good to call startactivity() Intent intent = new Intent(Intent.ACTION_SEND) in.putextra(intent.extra_text, msg); in.settype( text/plain ); ComponentName name = in.resolveactivity(getpackagemanager());

16 Implicit Intents Package Manager How about another way? We query for compatible activates, check if the list > 0 and process: PackageManager packagemanager = getpackagemanager(); List activities = packagemanager.queryintentactivities( intent, PackageManager.MATCH_DEFAULT_ONLY); boolean isintentsafe = activities.size() > 0;

17 Implicit Intents - Sharing Create a new intent with the action to send: if(componentname!= null) startactivity(intent.createchooser(in, Share via )); else { } Toast.makeText(ShareIntentActivity.this, No activity found to handle sending plain text., Toast.LENGTH_LONG).show();

18 Implicit Intents - Sharing The settype method takes a MIME type, lowercase only Multipurpose Internet Mail Extension Relates filenames to a short text description: HTML text/html CSS text/css Search online for a list of types:

19 Implicit Intents Becoming a Choice Let s become a choice! Create a new blank activity with textview and go to manifest Add new intent filter for the activity: <activity android:name=.receiveshareactivity > <intent-filter> <action android:name= android.intent.action.send /> <category android:name= android.intent.category.default /> <data android:mimetype= text/plain /> </intent-filter> </activity> The mimetype helps determine what choosers can support this send request, try text/html and see the list differences!

20 Implicit Intents Becoming a Choice We now need to handle receiving an intent and pull the attached data When app launched from chooser, oncreate method is called We can get access to the intent that was supplied by calling: Intent intent = getintent(); String action = intent.getaction(); String type = intent.gettype();

21 Implicit Intents Becoming a Choice Check the action type to see if we can handle this intent & set our TextView s text: if(intent.action_send.equals(action) && type!= null) { if("text/plain".equals(type)){ String extratext = intent.getstringextra(intent.extra_text); } if(text!= null) text.settext(extratext); }

22 Implicit Intents Becoming a Choice

23 Implicit Intents Launching Telephone Let s launch an App to call our favorite pizza shop: Change our old layout: Dialing a number doesn t require permission Calling a number automatically DOES require a permission: <uses-permission android:name= android.permi ssion.call_phone />

24 Implicit Intents Launching Telephone Get a reference to the button Create a new method in our main activity to be called by button listener button_emergencypizza.setonclicklistener(new View.OnClickListener() public void onclick(view v) { Intent intent = new Intent(Intent.ACTION_DIAL); intent.setdata(uri.parse("tel: :")); if(intent.resolveactivity(getpackagemanager())!=null) startactivity(intent); }});

25 Implicit Intents Launching Settings As we start implementing features, we need to ask the user to turn on settings (wifi, location, nfc, Bluetooth, etc ) We can perform system setting actions such as: ACTION_SETTINGS ACTION_WIRELESS_SETTINGS ACTION_AIRPLANE_MODE_SETTINGS ACTION_WIFI_SETTINGS ACTION_BLUETOOTH_SETTINGS ACTION_LOCALE_SETTINGS ACTION_DISPLAY_SETTINGS ACTION_SECURITY_SETTINGS ACTION_LOCATION_SOURCE_SETTINGS ACTION_INTERNAL_STORATE_SETTINGS ACTION_MEMORY_CARD_SETTINGS

26 Implicit Intents Launching Settings Make a new button called wireless settings Grab a reference to the button and onclick the following: button_wireless.setonclicklistener(new View.OnClickListener() public void onclick(view v) { Intent intent = new Intent(Settings.ACTION_WIFI_SETTINGS); if(intent.resolveactivity(getpackagemanager())!=null) startactivity(intent); }});

27 ListView A ListView will host only enough entries for what is visible on the screen + 2 Even if we have items, the ListView will only generate what is needed It will recycle old elements to conserve resources A ListView and GridView are both children of the AdapterView We need something to convert our data arrays into ListView entries View 0 View 1 View 2 View 3 View 4 View 5

28 ListView + Adapters An Adapter will handle converting our data into a format that ListView or GridView can use to populate the screen We bind the adapter to the AdapterView Two common Adapters include: ArrayAdapter for array data sources, calling tostring on each element to create a view SimpleCursorAdapter when using cursors, such as from Contacts or other databases

29 Adapters Create an adapter specifying the type of the object being contained: ArrayAdapter<String> new ArrayAdapter<String>( this, android.r.layout.simple_list_item_1, mystringarray); Arguments: context, a TextView layout to use for views and the array of objects Call setadapter() on the ListView: ListView lv = (ListView) findviewbyid(r.id.listview); listview.setadapter(adapter);

30 ArrayAdapter The adapter is responsible for: 1. Creating the view object 2. Populating the view object with data 3. Returning the view object to the ListView An adapter can be any class that implements the Adapter interface ArrayAdapters<T> knows how to work with data stored in arrays OR lists!

31 Adapter Example listview =(ListView) findviewbyid(r.id.listview); String[] strings = {"Hello", "mother", "hello", "father", "here", "I", "am"}; ArrayAdapter<String> arrayadapter = new ArrayAdapter<String>( this, android.r.layout.simple_list_item _1, strings); listview.setadapter(arrayadapter);

32 ArrayAdapter The adapter and the ListView will have a conversation: ListView: How many items do you have? (getcount) Adapter: I have 3 items ListView: Send me View0 Adapter: (getview) create, populate & return View0 ListView: Send me View1 Adapter: (getview) create, populate & return View1 ListView: Send me View2 Adapter: (getview) create, populate & return View2

33 ArrayAdapter What if we are using other objects and not Strings? The default implementation of ArrayAdapter<T> will use the tostring() method of the data object to populate the view We the tostring() method if we are using our own data type Else: fully-qualified class name and memory address in the list view

34 ArrayAdapter private class Transaction{ private double amount; private String location; public Transaction(int number, double amount, String location){ this.number = number; this.amount = amount; this.location = location; public String tostring() { return "Number: " + this.number + "\namount: " + amount + "\nlocation: " + location; } }

35 Custom TextView We can also create our own TextView for the ListView Allow us to affect the text style, color, gravity, etc: Create an new layout called: textview_test Alter the properties to your liking Use this view layout when creating the ArrayAdapter: ArrayAdapter<Transaction> arrayadapter = new ArrayAdapter<Transaction>( this, R.layout.test_text_view, transactions);

36 Custom TextView We can also create our own TextView for the ListView Allow us to affect the text style, color, gravity, etc: Create an new layout called: textview_test Alter the properties to your liking Use this view layout when creating the ArrayAdapter:

37 List Fragment To handle list item clicks, Override the onlistitemclick public void onlistitemclick(listview l, View v, int position, long id) The ListView clicked The view in the list view clicked The view s position in the list The row id of the item clicked

38 ArrayAdapter Extended If we want more than a text view, we will need to implement our own version of ArrayAdapter 1. Create a new custom layout for the list item 2. Create a new class that inherits from ArrayAdapter 3. Our ArrayAdapter class must be able to: 1. Create 2. Populate 3. Return the new layout

39 ArrayAdapter Extended Custom Layout with a Linear Layout, image, checkbox and text area: Create a new class that inherits from ArrayAdapter private class CustomAdapter extends ArrayAdapter<Transaction>{ public ProfileAdapter( ArrayList<Transaction> transactions ){ super(getapplicationcontext(), 0, transactions); }

40 ArrayAdapter Extended private class CustomAdapter extends ArrayAdapter<Transaction>{ public CustomAdapter(Context context, Transaction[] transactions){ super(context, public View getview(int position, View convertview, ViewGroup parent){ Transaction transaction = getitem(position); if(convertview == null){ convertview = LayoutInflater.from( getcontext()).inflate( R.layout.layout_listview_custom, null, false);} TextView text=(textview)convertview.findviewbyid(r.id.textview); text.settext(transaction.tostring()); return convertview; }}

41 ArrayAdapter Extended You should now have the following:

42 Pictures with Intents Since this app will require a camera to function, we need to add the <uses-feature> tag in the manifest: <uses-feature android:name="android.hardware.camera android:required="true"/> If the camera is not required, but still potential used in a feature set required to false and check at runtime with: if(getpackagemanager(). hassystemfeature( PackageManager.FEATURE_CAMERA))

43 Pictures with Intents An implicit intent can be used to call a camera application and receive picture data from it Create a layout with an image view and a button We will populate the ImageView with the camera data we receive We need to first check if the system can support the image capture:

44 Pictures with Intents Create an intent that requests for an action for image capture Resolve whether or not we have an app that can handle it If yes, start the activity and pass in an Integer identifier Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); if(i.resolveactivity( getpackagemanager())!= null) { startactivityforresult(i, REQUEST_IMAGE_CAPTURE); }

45 Pictures with Intents Intents can transfer around 500kB of data before crashing your application Photos from most cameras are too large to transfer through Intents If all you want is a small thumbnail, it can be returned by the intent in onactivityresult() under the key protected void onactivityresult(int requestcode, int resultcode,intent data) { super.onactivityresult(requestcode, resultcode, data); } if(requestcode == REQUEST_IMAGE_CAPTURE && resultcode == RESULT_OK) { Bundle extras = data.getextras(); Bitmap imagebitmap = (Bitmap) extras.get("data"); imageview.setimagebitmap(imagebitmap); }

46 Full Size Pictures with Intents The camera application can save a full-size photo if it has a file to save into (fully qualified name to place the photo) Typically, this is public external storage accessible by all apps: getexternalstoragepublicdirectory(directory_pictures) We require the manifest permission WRITE_EXTERNAL_STORAGE, which gives us both write and read access <uses-feature android:name="android.hardware.camera android:required="true"/> <uses-permission android:name= "android.permission.write_external_storage"/>

47 Full Size Pictures with Intents The filename we decide to use needs to be unique (free of naming collisions) We can do this with either the time stamp String string = new SimpleDateFormat( "yyyymmdd_hhmmss"). format(new Date()); We can also do this with a UUID (universally unique identifier) UUID uniqueid = UUID.randomUUID();

48 Full Size Pictures with Intents private File createimagefile() throws IOException { File image; String filename = "JPEG_" + UUID.randomUUID().toString() + "_"; String extension = ".jpg"; File dir = getexternalfilesdir( Environment.DIRECTORY_PICTURES); image = File.createTempFile(fileName, extension, dir); photopath = image.getabsolutepath(); } return image;

49 Full Size Pictures with Intents private void takepicture() { Intent pi = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); if(pi.resolveactivity(getpackagemanager())!= null) { File photofile = null; try{ photofile = createimagefile(); } catch(ioexception io) {} if(photofile!= null) { Uri uri = FileProvider.getUriForFile(this, "com.georgelecakes.android.fileprovider", photofile); pi.putextra(mediastore.extra_output, uri); startactivityforresult(pi, REQUEST_IMAGE_CAPTURE); } } }