singleTop behaves as documented for m (i.e. creating a new Activity at
the top of the stack, or reusing one if there is already an Activity
of that type at the top of the stack). I'm pretty sure singleTask is
documented incorrectly though. I'm just wondering whether I've got it
wrong, since this is completely fundamental (its in the "Android
fundamentals" document, so how has no-one else picked up on it?
On 11 Sep, 04:30, joebowbeer <joe.bowb...@gmail.com> wrote:
> I agree that the documentation is confusing and possibly wrong.
>
> For the second behavior, that of discarding the intent and bringing
> the task with the specified activity to the foreground, you should use
> "singleTop" instead (despite what the documentation says).
>
> On Sep 10, 4:00 pm, Olly <ollywood...@gmail.com> wrote:
>
>
>
> > I've been learning Android and have come across an issue with
> > launchMode="singleTask". The documentation states that when this
> > attribute is used, the Activity is always launched into a new task as
> > the root Activity. Secondly, the documentation states that if an
> > Intent is targeted at such an Activity when there are Activities
> > sitting above it in its task stack, such Intents are discarded
> > (although the task is still brought to the foreground).
>
> > I've been playing around with this, and the behaviour I observe is
> > completely different. In particular: - Activities with
> > launchMode="singleTask" are not always the root Activity in a task
> > stack. They are just plonked ontop of the existing stack with the same
> > affinity. - When an Intent is targeted at such an Activity and there
> > are other Activities above it in the stack, the Intent is not
> > discarded. Instead the Activities above it in the stack are discarded.
> > The Intent is then delivered via onNewIntent to the Activity as
> > normal.
>
> > Can someone confirm that this is the actual behaviour? If so, why are
> > the documents incorrect? If not what have I done wrong. . . Here is a
> > simple way to observe the behaviour:
>
> > 1. Create a simple main.xml containing two buttons b1 and b2.
> > 2. Create the following Activity:
>
> > public class ActivityA extends Activity {
>
> > @Override
> > public void onCreate(final Bundle savedInstanceState) {
> > super.onCreate(savedInstanceState);
> > setContentView(R.layout.main);
>
> > Button lButton = (Button) findViewById(R.id.b1);
> > lButton.setOnClickListener(new OnClickListener() {
> > @Override
> > public void onClick(View arg0) {
> > Intent lNextIntent = new
> > Intent(ActivityA.this,ActivityA.class);
> > startActivity(lNextIntent);
> > }
> > });
>
> > Button lButton2 = (Button) findViewById(R.id.b2);
> > lButton2.setOnClickListener(new OnClickListener() {
> > @Override
> > public void onClick(View arg0) {
> > Intent lNextIntent = new
> > Intent(ActivityA.this,ActivityB.class);
> > startActivity(lNextIntent);
> > }
> > });
> > }
>
> > }
>
> > 3. Create the second Activity:
>
> > public class ActivityB extends ActivityA {
>
> > }
>
> > 4. The manifest:
>
> > <?xml version="1.0" encoding="utf-8"?>
> > <manifest xmlns:android="http://schemas.android.com/apk/res/android";
> > package="ojw28.activitytest"
> > android:versionCode="1"
> > android:versionName="1.0">
> > <application android:icon="@drawable/icon" android:label="@string/
> > app_name">
> > <activity android:name="ActivityA"
> > android:label="@string/app_name">
> > <intent-filter>
> > <action android:name="android.intent.action.MAIN" />
> > <category
> > android:name="android.intent.category.LAUNCHER" />
> > </intent-filter>
> > </activity>
> > <activity android:name=".ActivityB"
> > android:launchMode="singleTask">
> > </activity>
> > </application>
> > </manifest>
>
> > 5. Launch the application. Press button b1 a couple of times, see what
> > happens to the task stack using "adb shell dumpsys activity". Multiple
> > instances of ActivityA are now in the task stack as expected.
>
> > Now press button b2. According to the documentation this should launch
> > an ActivityB instance is a NEW task, as the root Activity of that
> > task. Use adb to look at the stack. What actually happens is ActivityB
> > gets put ontop of the current stack, which isn't the documented
> > behaviour.
>
> > Now press button b1 a couple more times. Then press b2 again. Since
> > the single instance of ActivityB isn't at the top of the stack, the
> > documentation states that this intent should be ignored. The observed
> > behaviour is that all ActivityA instances above the ActivityB instance
> > are discarded from the stack, after which the intent is delivered to
> > the instance of ActivityB as normal (via onNewIntent - you can
> > override this method and add a break point to observe this).
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
