This document discusses intents in Android. It explains that intents are used to invoke activities both internally and externally. An intent can be used to explicitly start a new activity by creating an intent, putting extras like key-value pairs, and calling startActivity. This is demonstrated with code examples of two activities - Activity01 starts Activity02 by creating an intent and passing an ID extra, which Activity02 retrieves using getIntent().getExtras().

1. 08. Intent (Explicit)
Oum Saokosal
Master of Engineering in Information Systems, South Korea
855-12-252-752
oum_saokosal@yahoo.com

2. Agenda
• What is Intent?
• Intent: Invoke another Activity explicitly
• Put Extra with Intent

3. What is Intent? (1)
• There are many uses of intent.
– You can use intents to invoke other applications
from your application.
– You can use intents to invoke internal or external
components from your application.
– You can use intents to raise events so that others
can respond in a manner similar to a publish-and
subscribe model.

4. What is Intent? (2)
• At the simplest level, an intent is an action that
you can tell Android to invoke. That is, you can
invoke activity 02 from activity 01.
• In order to invoke like that, you need to register
those activities in AndroidManifest.xml.
• See Example: IntentExplicit.

5. Intent: Invoke another Activity
explicitly

6. public class Activity01 extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main01);
}
public void gotoProfile(View v){
Intent in = new Intent(this, Activity02.class);
startActivity(in);
}
}

7. main01.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Name: Oum Saokosal" />
……
……
……
<Button
android:onClick="gotoProfile"
android:id="@+id/btnProfile"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Profile" />
</LinearLayout>

8. public class Activity02 extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main02);
}
public void backtoMain(View v){
Intent in = new Intent(this, Activity01.class);
startActivity(in);
}
}

9. main02.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Relationship: Engaged"
android:textAppearance="?android:attr/textAppearanceMedium" />
……
……
<Button
android:onClick="backtoMain"
android:id="@+id/btnBack"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Back"/>
</LinearLayout>

10. AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.kosalab" android:versionCode="1" android:versionName="1.0" >
<uses-sdk android:minSdkVersion="10" />
<application
android:icon="@drawable/ic_launcher"
android:label="Intent Explicit" >
<activity
android:label="Activity01"
android:name=".Activity01" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:label="Activity02" android:name=".Activity02"></activity>
</application>
</manifest>

11. Put Extra with Intent
• In PHP, you can send data from a file to
another file through session.
• Similar to that, you can send data from one
Activity to other one by putting extra with
Intent.
• The extra data is in the form of key/value
pairs.

12. putExtra() into Intent
public class Activity01 extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main01);
}
public void gotoProfile(View v){
Intent in = new Intent(this, Activity02.class);
in.putExtra("id", "4312");
startActivity(in);
}
}

13. getExtras() from getIntent
public class Activity02 extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main02);
Bundle extras = getIntent().getExtras();
if (extras != null) {
int id = 0;
if(extras.getString("id") != null){
id = Integer.parseInt(extras.getString("id"));
Toast.makeText(this,
"your id = " + id, Toast.LENGTH_LONG).show();
}
}
}
public void backtoMain(View v){
Intent in = new Intent(this, Activity01.class);
startActivity(in);
}
}

15. Go on to the next slide