LinearLayout and its Important Attributes with Examples in Android - Software Development PDF Download

LinearLayout and its Important Attributes with Examples in Android

LinearLayout is a fundamental layout in Android Studio that arranges all child elements sequentially either horizontally or vertically based on the android:orientation attribute. When android:orientation="vertical" is set, elements are positioned in a vertical sequence, whereas when android:orientation="horizontal" is set, elements are placed in a horizontal sequence.

android:orientation

• android:orientation="vertical"
• android:orientation="horizontal"

Sample Code of LinearLayout

Explanation:

The above code snippet demonstrates the structure of a LinearLayout in XML format. Here, the layout is set to occupy the entire width and height of the parent container with a vertical orientation.

Key Points:

• The android:layout_width and android:layout_height attributes determine the width and height of the LinearLayout, set here to match the parent's dimensions.
• The android:orientation attribute specifies the orientation of the layout, either vertical or horizontal.

Example:

Consider a scenario where you want to design a login screen using a LinearLayout with a vertical orientation to stack the username and password fields one above the other.

Implementation Steps:

• Create a new LinearLayout in your XML layout file.
• Set the android:orientation attribute to "vertical" within the LinearLayout tag.
• Add EditText views for the username and password fields inside the LinearLayout.
• Customize the styling and attributes of the EditText views as needed.

Some Important Attributes of LinearLayout

• android:layout_weight: It is used to specify how LinearLayout divides the remaining space among the views it contains.
• android:weightSum: This attribute defines the total weight sum in a LinearLayout.
• android:orientation: Specifies whether the elements should be arranged horizontally or vertically.
• android:gravity: Determines how an object should position its content on the X and Y axes, with values like center_vertical, fill, center, bottom, end, etc.
• android:layout_gravity: Sets the gravity of the View or Layout relative to its parent, with possible values like center_vertical, fill, center, bottom, end, etc.
• android:baselineAligned: A boolean value (true/false) that prevents the layout from aligning its children's baselines.
• android:id: Provides a unique id to the layout.

Examples

• How to arrange children views in a vertical manner:

  Here is an XML snippet demonstrating vertical arrangement:

  Output UI:

  

How to Arrange Children Views in a Horizontal Manner

• Use a LinearLayout with android:orientation set to horizontal.
• Add Button elements inside the LinearLayout with appropriate attributes.
• Set android:layout_width to "wrap_content" and android:layout_height to "match_parent" for the Buttons.
• Include android:layout_margin with a specified value for spacing between Buttons.

How to Use layout_weight and weightSum

• Within a LinearLayout, set android:orientation to horizontal and android:weightSum to a numerical value.
• Assign android:layout_weight to child views to define their proportional sizes.
• Ensure the total of layout_weight values does not exceed the weightSum value to maintain correct proportions.

How to Use Gravity

• To control the placement of a view's content, utilize the gravity attribute.
• Gravity can be set to values like "center", "top", "bottom", "left", "right", etc., based on the desired positioning.
• Applying gravity influences how the content is aligned within the view's boundaries.

4. How to use gravity

• Gravity is used in Android layouts to control the positioning of elements.
• android:gravity attribute is used to set the gravity of the content of a View.
• Values like "center", "bottom", "top" can be used to set the gravity.

• Example:

  • If we set android:gravity="bottom|center" for a Button, the text inside will be centered horizontally and aligned to the bottom of the Button.
  • Setting android:gravity="center|top" will center the text horizontally and align it to the top of the Button.

Output of the above code:

5. How to use layout_gravity

• layout_gravity is used to control the alignment of a View within its parent layout.
• It is specific to the View and controls where the View should be placed in its parent layout.

• Example:

  • Setting layout_gravity="center" for a View will center the View itself within its parent container.
  • layout_gravity="start" will align the View to the start of the parent container.

5. How to Use layout_gravity

• layout_gravity in Android is used to control the alignment of a view within its parent layout.
• It is an attribute that can be applied to views in a LinearLayout to specify how the view should be positioned.
• Values for layout_gravity include "center," "right," and "left," among others.
• For example, setting layout_gravity to "center" will align the view to the center of the parent layout.

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