Linking Activities using Intents

1. Linking Activities using Intents How to navigate between Android Activities Linking Activities using Intents

2. Navigation from an Activity to another Activity • Create an Intent object • Intents can be created in different ways • Intents can carry data from the calling Activity to the called Activity • Start the other Activity, using the Intent object • When the called Activity ends (finish() method) the control is returned to the calling Activity • The return of controls can carry data back to the calling activity • Comparable to calling a method in Java. • You use the keyword return to get back to the calling method. • Example: IntentsSimple Linking Activities using Intents

3. Different ways of creating an Intent object • Creating an Intent object linking to an Activity in the same project • Intent intent = new Intent(this, Activity2.class) • Creating an Intent object linking to an Activity in another project • Intent intent = new Intent(”dk.easj.Activity2”); • The other project must register the Intent name in the AndroidManifest.xml <activity android:name=".Activity2" <!-- .class name --> android:label="Activity 2"> <intent-filter > <action android:name="dk.easj.Activity2" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </activity> Linking Activities using Intents

4. Returning results from an Intent • When the called Activity returns to the calling Activity, it can send data (results) • startActivity(…) No results • startActivityForResult(…) Results expected • startActivityForResult(intent, request_Code); • Callback method in calling Activity: Example, Lee page 52 protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == request_Code) { // which request? Same request_Code as in the startActivityForResult(…) if (resultCode == RESULT_OK) { // or RESULT_CANCELLED final String fullData = data.getData().toString(); … } } } • Example: IntentsPersonalInfo, Eclipse project Linking Activities using Intents

5. Passing data using an Intent object:Sending data • You can pass data from one Activity to another using the Intent object • Example: Sending data, Lee page 66 (54) Intent intent = new Intent(this, AnotherActivity.class); intent.putExtra(“name”, “Anders”); // Generally putExtra(key, value) startActivityForResult(intent, request_Code); Linking Activities using Intents

6. Passing data using an Intent object:Reading data • The receiving Activity can read the data. • Example: Reading data, Lee page 67, (54) Intent intent = getIntent(); CharSequence name = intent.getCharSequenceExtra(“name”); // CharSequence is s super-class of String • Example: IntentsPersonalInfo, Eclipse project Linking Activities using Intents

7. Making activities look like dialogs • With an Intent you go to another Activity. • Dialogs on the other hand usually show up on top of another Activity. • Activities can look like Dialogs • Shown on top of another Activity • Example: AndroidManifest.xml <activity android:name=".NameDialogActivity" android:theme="@android:style/Theme.Dialog"> </activity> Linking Activities using Intents

8. Navigation to a built-in application using Intents • Android has several built-in applications • Browser, phone, etc. • You can navigate from you Activity to the built-in applications using Intent pairs Linking Activities using Intents

9. Intent pairs (action, data) • Action • Describes what to be done • Examples: View an item, Edit an item, etc. • Action examples: ACTION_VIEW, ACTION_DIAL, ACTION_PICK • Data • Describes which ”object” the intent affects • http://www.google.com • Tel:+4560609528 • Geo:38.999,-44.44 • Content://contacts • Code example • Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.amazon.com")); • Example: IntentsForStandardApps Linking Activities using Intents

10. Using Intent Filters • If you want other activities to invoke you activity, you must specify some Intent Filters in the AndroidManifest.xml file. • Example: IntentsSimple Linking Activities using Intents