#Androdi training# interactions with activities or apps

一  to Other's Apps

explicit intent

Intent mIntent = new Intent();
mIntent.setClass(this,MainConversationActivity.class);
startActivity(mIntent);

implicit intent

call:

Uri number = Uri.parse("tel:5551234");
Intent callIntent = new Intent(Intent.ACTION_DIAL, number);

map:

// Map point based on address
Uri location = Uri.parse("geo:0,0?q=1600+Amphitheatre+Parkway,+Mountain+View,+California");
// Or map point based on latitude/longitude
// Uri location = Uri.parse("geo:37.422219,-122.08364?z=14"); // z param is zoom level
Intent mapIntent = new Intent(Intent.ACTION_VIEW, location);

view a page

Uri webpage = Uri.parse("http://www.android.com");
Intent webIntent = new Intent(Intent.ACTION_VIEW, webpage);

tips:

1.you can add more data through putExtra()

2.if you don't include a Uri in the intent, you should usually use setType() to specify the type of data

associated with the intent.

send an email with an attachment

Intent emailIntent = new Intent(Intent.ACTION_SEND);
// The intent does not have a URI, so declare the "text/plain" MIME type
emailIntent.setType(HTTP.PLAIN_TEXT_TYPE);
emailIntent.putExtra(Intent.EXTRA_EMAIL, new String[] {"[email protected]"}); // recipients
emailIntent.putExtra(Intent.EXTRA_SUBJECT, "Email subject");
emailIntent.putExtra(Intent.EXTRA_TEXT, "Email message text");
emailIntent.putExtra(Intent.EXTRA_STREAM, Uri.parse("content://path/to/email/attachment"));
// You can also attach multiple items by passing an ArrayList of Uris

create a calendar event

Intent calendarIntent = new Intent(Intent.ACTION_INSERT, Events.CONTENT_URI);
Calendar beginTime = Calendar.getInstance().set(2012, 0, 19, 7, 30);
Calendar endTime = Calendar.getInstance().set(2012, 0, 19, 10, 30);
calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, beginTime.getTimeInMillis());
calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_END_TIME, endTime.getTimeInMillis());
calendarIntent.putExtra(Events.TITLE, "Ninja class");
calendarIntent.putExtra(Events.EVENT_LOCATION, "Secret dojo");

3.you may need to verify if there is an app to receive the intent

PackageManager packageManager = getPackageManager();
List activities = packageManager.queryIntentActivities(intent,
        PackageManager.MATCH_DEFAULT_ONLY);
boolean isIntentSafe = activities.size() > 0;

if(isIntentSafe){ startActivity(mapIntent);}

4. show the chooser

Intent intent = new Intent(Intent.ACTION_SEND);
...

// Always use string resources for UI text.
// This says something like "Share this photo with"
String title = getResources().getString(R.string.chooser_title);
// Create intent to show chooser
Intent chooser = Intent.createChooser(intent, title);

// Verify the intent will resolve to at least one activity
if (intent.resolveActivity(getPackageManager()) != null) {
    startActivity(chooser);
}

二  getting a Result from an Activity

startActivityForResult()

onActivityResult()

static final int PICK_CONTACT_REQUEST = 1;  // The request code. Later, you app can properly identify the result and determine how to handle it.
...
private void pickContact() {
    Intent pickContactIntent = new Intent(Intent.ACTION_PICK, Uri.parse("content://contacts"));
    pickContactIntent.setType(Phone.CONTENT_TYPE); // Show user only contacts w/ phone numbers
    startActivityForResult(pickContactIntent, PICK_CONTACT_REQUEST);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // Check which request we're responding to
    if (requestCode == PICK_CONTACT_REQUEST) {
        // Make sure the request was successful
        if (resultCode == RESULT_OK) {
            // The user picked a contact.
            // The Intent's data Uri identifies which contact was selected.

            // Do something with the contact here (bigger example below)
        }
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // Check which request it is that we're responding to
    if (requestCode == PICK_CONTACT_REQUEST) {
        // Make sure the request was successful
        if (resultCode == RESULT_OK) {
            // Get the URI that points to the selected contact
            Uri contactUri = data.getData();
            // We only need the NUMBER column, because there will be only one row in the result
            String[] projection = {Phone.NUMBER};

            // Perform the query on the contact to get the NUMBER column
            // We don't need a selection or sort order (there's only one result for the given URI)
            // CAUTION: The query() method should be called from a separate thread to avoid blocking
            // your app's UI thread. (For simplicity of the sample, this code doesn't do that.)
            // Consider using CursorLoader to perform the query.
            Cursor cursor = getContentResolver()
                    .query(contactUri, projection, null, null, null);
            cursor.moveToFirst();

            // Retrieve the phone number from the NUMBER column
            int column = cursor.getColumnIndex(Phone.NUMBER);
            String number = cursor.getString(column);

            // Do something with the phone number...
        }
    }
}

三 allwoing other apps to start your activity

Action:

ACTION_SEND

ACTION_VIEW

Data:

A description of the data associated with the intent.

you can specify the MIME type

Note: if you don't need to declare specifics about data Uri(such as when your activity handles to other kind of "extra")

 data, instead of a Uri), you should specify only the android:mimeType attribute to declare the type of data, such as text/plain or image/jpeg

Category:

rarely used.

handle the Intent

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    // Get the intent that started this activity
    Intent intent = getIntent();
    Uri data = intent.getData();

    // Figure out what to do based on the intent type
    if (intent.getType().indexOf("image/") != -1) {
        // Handle intents with image data ...
    } else if (intent.getType().equals("text/plain")) {
        // Handle intents with text ...
    }
}

return a result

when your operation is done and the user should returen original activity, call finish() to close (and destroy) your activity.

Intent result = new Intent("com.example.RESULT_ACTION", Uri.parse("content://result_uri"));
setResult(Activity.RESULT_OK, result);
finish();

the default is RESULT_CANCELED.

setResult(RESULT_COLOR_RED);
finish();

the intent is not necessary.