In this page, http://androidapps.org.ua/androidintro_ipc.html , intent switching between activities is described as Inter Process Communication. Now I am confused whether every activity is a separate process in android or All activities inside an application is one process. I have checked the process id of all activities and service in my Application using:
int id = android.os.Process.myPid();
System.out.println("Process id of Activity1 :"+id);
But it is showing same process id. Please reply back.
All activities inside an application run in one process?
It depends on value of android:process
attribute in application manifest.
if attribute android:process
is not defined for Application/Activity tags in the manifest, by default all the activities will run in single process (process name will be name of the package defined in manifest)
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.so.test" android:versionCode="1" android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".Activity1">
</activity>
<activity android:name=".Activity2">
</activity>
<activity android:name=".Activity3">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
In the above manifest all activities run in process com.so.test
,ps command output in adb shell:
# ps
app_39 668 33 84492 20672 ffffffff afd0c51c S com.so.test
If android:process
is specified for Activity new process will be created with the same userid and the activity runs in that process.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.so.test" android:versionCode="1" android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />
<application android:icon="@drawable/icon" android:label="@string/app_name"
android:process="com.so.p1">
<activity android:name=".Activity1">
</activity>
<activity android:name=".Activity2" android:process="com.so.p2">
</activity>
<activity android:name=".Activity3" android:process="com.so.p3">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
If the manifest is defined like above
Activity1 runs in com.so.p1 process
Activity2 runs in com.so.p2 process
Activity3 runs in com.so.p3 process
ps output in adb shell
# ps
app_39 650 33 83192 20900 ffffffff afd0c51c S com.so.p1
app_39 659 33 83188 20864 ffffffff afd0c51c S com.so.p2
app_39 668 33 84492 20672 ffffffff afd0c51c S com.so.p3
If an Activity needs to be run in another process not defined in this manifest, both APKs should be signed with the same certificate.