1. What is Android Activity Launch Mode
There are basically 4 launch mode while launching activity in Android.
a. Standard Mode(Default Mode)
This is the default launch mode of activity (If not specified). It launches a new instance of an activity in the task from which it was launched. Numerous instances of the activity can be generated, and multiple instances of the activity can be assigned to the same or separate tasks. In other words, you can create the same activity multiple times in the same task as well as in different tasks.
b. Single Top
If an instance of the activity already exists at the top of the current task in this launch mode, no new instance will be generated, and the Android system will send the intent data through onNewIntent() method. If an instance does not exist on top of the task, a new instance will be generated. You can use this launch mode to generate numerous instances of the same activity within the same task or across tasks, but only if the identical instance does not already exist at the top of the stack.
c. Single Task
In this method of operation, a new task is always generated, and a new instance is added to the task as the root one. If the activity already exists on another task, no new instance is created, and the Android system transmits the intent information via the onNewIntent() function. At any one time, there will be just one instance of the activity.
d. Single Instance
This is a highly unique start option that is only used in programs with a single activity. It works similarly to Single Task, except that no additional activities are generated in the same task. Any further activity initiated from this point will result in the creation of a new task.