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Intents

Intents. Intents. Message passing mechanism Most common uses: starting an Activity (open an email, contact, etc.)   starting an Activity for a result (scan a barcode, take a picture to attach to an email, etc .). Intents. Explicit

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Intents

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  1. Intents CS440

  2. Intents • Message passing mechanism • Most common uses: • starting an Activity (open an email, contact, etc.)  •  starting an Activity for a result (scan a barcode, take a picture to attach to an email, etc.) CS440

  3. Intents • Explicit Intent i = new Intent(this, ActivityTwo.class); i.putExtra("Value1", "This value one for ActivityTwo "); i.putExtra("Value2", "This value two ActivityTwo"); • Implicit Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.vogella.com")); startActivity(i); CS440

  4. Example: Share Intent • SenderIntent intent = new Intent(Intent.ACTION_SEND); intent.setType("text/plain"); intent.putExtra(android.content.Intent.EXTRA_TEXT, "News for you!"); startActivity(intent); • Receiver Bundle extras = getIntent().getExtras(); if(extras == null) { return; } // Get data via the key String value1 = extras.getString(Intent.EXTRA_TEXT); if(value1 != null) { // Do something with the data } CS440

  5. Calling Sub-Activities for result data • If you need some information from the called Activity use thestartActivityForResult() method. publicvoidonClick(View view) { Intent i = new Intent(this, ActivityTwo.class); i.putExtra("Value1", "This value one for ActivityTwo "); i.putExtra("Value2", "This value two ActivityTwo"); // Set the request code to any code you like, you can identify the// callback via this code startActivityForResult(i, REQUEST_CODE); } CS440

  6. Calling Sub-Activities for result data • If you use the startActivityForResult() method then the started Activity is called a Sub-Activity. • If the Sub-Activity is finished it can send data back to its caller via Intent. This is done in the finish() method. @Override publicvoid finish() { // Prepare data intent Intent data = new Intent(); data.putExtra("returnKey1", "Swinging on a star. "); data.putExtra("returnKey2", "You could be better then you are. "); // Activity finished ok, return the data setResult(RESULT_OK, data); super.finish(); } CS440

  7. Calling Sub-Activities for result data • Once the Sub-Activity finished, the onActivityResult() method in the calling Activity will be called. @Override protectedvoidonActivityResult(intrequestCode, intresultCode, Intent data) { if(resultCode == RESULT_OK && requestCode == REQUEST_CODE) { if(data.hasExtra("returnKey1")) { Toast.makeText(this, data.getExtras().getString("returnKey1"), Toast.LENGTH_SHORT).show(); } } } CS440

  8. Intents • Intents use action strings and URIs: • Action Strings Example: • ACTION_VIEWcontent://contacts/people/1 -- Display information about the person whose identifier is "1“ • ACTION_DIALcontent://contacts/people/1 -- Display the phone dialer with the person filled in. • ACTION_DIALtel:123 -- Display the phone dialer with the given number filled in. • URI Example: • Search Google Maps: geo:0,0?q=query • Show contacts: content://contacts/people • Show a URL: http://www.google.com  CS440

  9. Intent Fun • Create a new Project: IntentFun • Create an intent that has data one of the following URIs: • http://www.google.com • content://contacts/people • geo:0,0?q=query • Do not forget to start an Activity for this intent! CS440

  10. Intent Fun • Create an intent that takes a picture: • Use: "android.media.action.IMAGE_CAPTURE“ as an argument in the intent • Start an activity that is based on the result of the intent • Do not forget: you need to override the onActivityResult method… why? CS440

  11. Intent Fun • Create a Toast with text “lalala”: • What is a Toast class? • Make the text appear on your screen • Check the open intents registry: • http://www.openintents.org/en/intentstable CS440

  12. References • http://www.damonkohler.com/2009/02/android-recipes.html • http://developer.android.com CS440

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