CODEWITHSUNDEEP
androidlaunchmode
mianlaoshu
mianlaoshu

Reputation: 2592

Android: when should I use singleInstance launchmode

There are four launch modes for an Activity, standard, singletop, singletask, and singleInstance. The previous three are relatively easy understanding and widely used. But till now, I did not find any scenario using singleInstance.

Some of the real use case is an Activity for Launcher or the application that you are 100% sure there is only one Activity

Have any one used it before?

Upvotes: 4

Views: 4362

Answers (3)

Braj Bhushan Singh
Braj Bhushan Singh

Reputation: 627

singleInstance launchmode will be used when you do not want any other activity to be a part of the task.Its the only activity in the task. As this launchmode does not permit that.

Upvotes: -2

David Wasser
David Wasser

Reputation: 95618

There is never a reason to use singleInstance launch mode.

If you are building a "home screen" replacement or a launcher type application, you would use singleInstance or singleTask launch mode to ensure that your Activity is always the root of its task. This makes sure that if another application launches your Activity, that Activity does not get launched into the task of the calling application and it also ensures that there is only ever one instance of your Activity created.

If you are writing a "home screen" replacement application, you can always make sure that no other activities get launched into your own task by always specifiying Intent.FLAG_ACTIVITY_NEW_TASK when launching other activities. In that case, you can use launch mode singleTask. So there is no reason to use launch mode singleInstance. But it probably wasn't clear to the original developers of Android at the time.

Upvotes: 4

Ritesh
Ritesh

Reputation: 896

SingleInstance launch mode should only be used in the applications that are implemented entirely as one activity. Only one instance will exist at a time. System will not launch any other activity into task holding this type. It is always a single member of its task and activities started from here will open into seperate task.

Upvotes: 1

Related Questions