Presented at session 3 of Android Study Jams

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Prior Programming Experience Track: Session 3
Android Study Jams
Android Facilitator: Ritika Talukdar

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Concept Overview

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Understanding Activity and Activity
Lifecycle
● An activity is a screen on your devices which consists of the user interface.
● It provides a window in which the app draws it UI.
● An activity has different states like create, pause, stop, destroy, etc.
Class Activity
{
methods ------> Callbacks
methods
}

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Main Activity Profile Activity Chat Activity

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Activity Lifecycle

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XML mainly uses tags to introduce elements into a layout, whether they’re views or viewgroups. A view is
basically any of the widgets that make up a typical utility app. Examples include:-
● Images (imageview)
● Text (textview)
● Editable text boxes (edittext)
● Buttons (button).
Introduction to XML

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Hello World!
<TextView
android:text="Hello World!"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
OR
<TextView>
android:text="Hello World!"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
</TextView>
Declare layouts in XML

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Conditions for Images
● The image should be of a small size, that is between 200 to 300 kb.
● The image should be in PNG format.
● The name of the image should be in a format like this: android_logo.png
● The name cannot have any capital letters, numbers, or special characters, except the
underscore.

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Understanding fragments
A fragment represents a behaviour or a part of the user interface in an activity.
We can combine multiple fragments in a single activity to build a multi-pane UI.

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Advantages of using fragments
● They take up lesser RAM than an activity. Hence, the app works faster with fragments than with
activities.
● They are reusable across multiple activities.

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