What Are Layouts In Android?: Everything You Need To Know

View Layouts in Android

The View is a base class for all the UI elements in Android apps, and it is used to build interactive UI components such as TextView, EditText, Button, Checkbox, RadioButton, ImageButton, ProgressBar, and ImageView. It is also responsible for creating dynamic or static elements on the screen and event handling for interaction with the user.

There are many View Layouts in Android, but listed below are some commonly used View layouts to build UI elements.

TextView Layout in Android

In Android, TextView is a user interface element used to display and set the static and dynamic text on the user screen based on our requirements. The TextView element acts like label control, and it doesn’t allow users to edit the text.

Create TextView in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <TextView
       android:id="@+id/textView_id"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_margin="10dp"
       android:text="Welcome to LambdaTest"
       android:textColor="#000000"
       android:textSize="24sp"
       android:textStyle="bold" />


</LinearLayout>

If you observe the above code carefully, you can see that we have used some attributes in this TextView element. These attributes are used to define the design and style of the layouts in Android and hence are important. Some of these attributes are common and can be applied in almost all the View elements in Android, while some are View specific.

Some common attributes that apply to all the layouts are id (Used to assign a unique ID to the view which can be used later to access them, here ), layout_width (used to define the width of the view, here wrap_content means that width will be minimum to cover the whole content inside it), layout_height (used to define the height of the view), and layout_margin (used to leave margin on the view).

Attributes specific to TextView are text (used to define the text that will be shown on the UI), textColor (used to set the text color), textSize (defines the font size of the text to display), and textStyle (used to define the text style like bold or italic).

Emulator Output:

EditText Layout in Android

EditText is a user interface element that allows the user to input and modify text/numbers through it. It is an extended version of the TextView element with few additional features and is used to let users enter input values.

Create EditText in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <EditText
       android:id="@+id/edittext_id"
       android:layout_height="wrap_content"
       android:layout_width="match_parent"
       android:hint="Input Hint"
       android:inputType="text"/>


</LinearLayout>

Attributes used in the above code for EditText are as:

The hint attribute is used to set the hint text into the EditText field. This text will appear in the input box when it is empty.

While using EditText control in our Android app, we must define the data type the text field can accept using the inputType attribute. For example, if our EditText should accept plain text, then we need to set the inputType attribute as “text”. In case it is used for a password, then we need to set the inputType as “textPassword”.

Emulator Output:

Button Layout in Android

The Button is a very crucial user interface element. It is used to perform an action whenever the user clicks or taps on it. Generally, Buttons in Android can contain text, icons, or both, or images and perform an action when the user touches it. Whenever the user clicks on any Button, the Button will call an on-click event.

Create a Button in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <Button
       android:id="@+id/btnId"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="I am Button"
       android:onClick="btnOperation"/>


</LinearLayout>

Attributes used in the above code for the Button are as:

The text attribute is used to set the text on the button. This text will appear on the button.

We can define the click event handler for the button by adding the onClick attribute to the < Button > object in our XML layout file.

Emulator Output:

CheckBox Layout in Android

A CheckBox is a two-state button that can be either unchecked (OFF) or checked (ON) and it permits users to toggle between the two states (OFF/ON) based on the requirements. Generally, we can use multiple CheckBox elements in an Android app to let users select multiple options from the set of values. By default, the Android CheckBox is always in the Unchecked (OFF) state.

Create a CheckBox in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <CheckBox
    android:id="@+id/chkBtnId"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:checked="true"
    android:text="LambaTest is Best" />


</LinearLayout>

The checked attribute is used to change the state of CheckBox to ON / OFF, if we need to set android:checked = “true” then our CheckBox will be in an ON state, while android:checked = “false” will set our CheckBox to OFF state.

Emulator Output:

RadioButton Layout in Android

The RadioButton is also a two-state button that can have two states either unchecked or checked, just like the CheckBox element, except that it allows only one option to be selected from the group of options. In Android, the CheckBox element permits users to change the state of control to either unchecked or Checked, but the RadioButton can’t be unchecked once it is checked.

We can use RadioButtons inside a RadioGroup to combine various RadioButtons into one group, and it will make sure that users can select only one option from the group of multiple options.

Create RadioButtons inside RadioGroup in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <RadioGroup
       android:id="@+id/radioGroup"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:orientation="vertical">


       <!-- Radio Button 1  -->
       <RadioButton
           android:id="@+id/radioBtn1"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="Option no 1"/>


       <!-- Radio Button 2  -->
       <RadioButton
           android:id="@+id/radioBtn2"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="Option no 2"/>
   </RadioGroup>
   
</LinearLayout>

In the above code for RadioGroup layouts in Android, the orientation attribute is used to specify the direction in which RadioButtons inside it will align. It can have two values horizontal or vertical.

Emulator Output:

ImageButton Layout in Android

The ImageButton is a user interface control element that is used to create buttons with an image and to trigger pre-specified action when a user taps or clicks on it. By default, an ImageButton looks the same as a normal Button, but the only difference between them is that we can add any custom image or icon to the button instead of plain text.

Create ImageButton in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <ImageButton
       android:id="@+id/imgBtnId"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:src="@drawable/custom_image"
       android:onClick="buttonClickOperation"/>


</LinearLayout>

Here while specifying ImageButton layouts in Android, we must define the src attribute which is used to specify or indicate the source file of the Image to be displayed on the ImageButton. We pass the actual image file to the src attribute, generally stored in the drawable or asset directory of the Android project.

Emulator Output:

ProgressBar Layout in Android

The ProgressBar is the user interface element used to indicate users for any ongoing progress of an operation like fetching data, uploading, downloading a file, etc. Any app that runs any time-consuming progress must use ProgressBar to keep the users notified about the progress otherwise, users may think that the app is lagging and hence could quit the app.

Create ProgressBar in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <ProgressBar
       android:id="@+id/progressBarId"
       style="?android:attr/progressBarStyleHorizontal"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:max="100"
       android:indeterminate="true"
       android:progress="50" />


</LinearLayout>

In the above code for creating ProgressBar, we used a few attributes that need to be understood to understand its behavior on UI.

The style attribute is mainly used to specify the layout design to be applied to the object. The value for this style attribute can be custom or system defined. Here we used ?android:attr/progressBarStyleHorizontal style which is specific to ProgressBar and it makes the ProgressBar horizontal, instead of the default style (circular).

The max attribute is used to define the maximum value for the ProgressBar. It must be an unsigned integer greater than equals to 1.

The progress attribute is used to set the progress completed at the instant. It can range from 0 to max.

The indeterminate attribute is used to enable/disable the indeterminate progress mode. By, default it has true value and is hence enabled. The Indeterminate progress mode in the ProgressBar is when we don’t know or specify how long a task will take or how much work has been done.

Emulator Output

ImageView Layout in Android

The ImageView is a user interface control element that is used to display an image on the screen. While specifying ImageView layouts in Android, we must define the src attribute which is used to specify or indicate the source file of the Image to be displayed on the ImageButton.

Create ImageView in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <ImageView
       android:id="@+id/imgViewId"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:src="@drawable/custom_image"/>


</LinearLayout>

Emulator Output:

ViewGroup Layouts in Android

The ViewGroup is a subclass of the View class and it acts as a base class for layouts and UI structure parameters. The ViewGroup provides us with an invisible container that can hold and arrange other Views and ViewGroups and define the main layout properties. For example, RelativeLayout is the ViewGroup that can contain other Views like Button, TextView, Images, other RelativeLayout, LinearLayout, etc.

Some common ViewGroup layouts in Android used to define the structure of screen UI are as follows:

LinearLayout in Android

The LinearLayout is a ViewGroup subclass that is used to arrange all child View elements one by one in the form of a queue either in a Vertical or Horizontal direction based on the orientation attribute. A pictorial representation of LinearLayout in Android apps is shown in the image below.

The above image clearly represents that in LinearLayout, if the orientation specified is horizontal, then the LinearLayout will have only one row of multiple columns otherwise, if the orientation is vertical, then it will have one column of multiple rows.

Create LinearLayout in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <TextView
       android:id="@+id/textView1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textColor="@color/black"
       android:textSize="40dp"
       android:text="First TextView" />
   <TextView
       android:id="@+id/textView2"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textColor="@color/black"
       android:textSize="40dp"
       android:text="Second TextView" />


</LinearLayout>

The above code will arrange the two TextViews in the vertical direction hence textview1 will come first in the list and below it will be textview2.

Emulator Output:

RelativeLayout in Android

As the name suggests, RelativeLayout ViewGroup is used to arrange the position of child Views relative to each other or relative to the parent. For example, here, we can arrange child View A to the left of child View B, and we may arrange View B to align the bottom of the parent.

RelativeLayouts in Android is mainly used to design complex layouts where the position of child View elements depends on other View’s position. A simple pictorial representation of Views inside a RelativeLayout is shown in the image below.

To achieve these multiple types of alignment in RelativeLayout we specify attributes to the child elements that define their position. These attributes are listed in the table below. We can use these attributes to form complex UI layouts in Android. Let’s consider an example of creating RelativeLayout.

Create RelativeLayout in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">
   
   <!-- It will appear on the top left of the parent -->
   <TextView
       android:id="@+id/textView1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textColor="@color/black"
       android:textSize="40dp"
       android:text="Hello,"
       android:layout_alignParentTop="true"
       android:layout_alignParentStart="true"/>


   <!-- It will appear on the bottom left of the parent -->
   <TextView
       android:id="@+id/textView2"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textColor="@color/black"
       android:textSize="40dp"
       android:text="Relative Layout!"
       android:layout_below="@id/textView1"
       android:layout_alignParentStart="true"/>


   <!-- It will appear below textview2 but horizontally centered -->
   <Button
       android:id="@+id/button"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Click Me"
       android:layout_below="@id/textView2"
       android:layout_centerHorizontal="true"
       android:layout_marginTop="16dp"/>


   <!-- It will appear at the end of the parent layout  -->
   <ImageView
       android:id="@+id/imageView"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/logo"
       android:layout_below="@id/button"
       android:layout_alignParentEnd="true"
       android:layout_marginTop="16dp"
       android:layout_marginEnd="16dp"/>


</RelativeLayout>

Emulator Output:

TableLayout in Android

TableLayout is a ViewGroup element that is used to arrange its child ViewElements in the form of a table with rows and columns. It will position its child View elements into columns and rows and not create any border lines for columns, rows, or cells.

Create TableLayout in an XML layout file

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16dp"
   tools:context=".ExampleActivity">


   <!-- Table Row 1 -->
   <TableRow>
       <!-- Table Cell 1 -->
       <TextView
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="Name:"
           android:paddingEnd="8dp" />


       <!-- Table Cell 2 -->
       <EditText
           android:id="@+id/editTextName"
           android:layout_width="0dp"
           android:layout_height="wrap_content"
           android:layout_weight="1"
           android:hint="Enter your name" />
   </TableRow>


   <!-- Table Row 2 -->
   <TableRow>
       <!-- Table Cell 1 -->
       <TextView
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="Email:"
           android:paddingEnd="8dp" />


       <!-- Table Cell 2 -->
       <EditText
           android:id="@+id/editTextEmail"
           android:layout_width="0dp"
           android:layout_height="wrap_content"
           android:layout_weight="1"
           android:hint="Enter your email" />
   </TableRow>


   <!-- Table Row 3 -->
   <TableRow>
       <!-- Table Cell 1 -->
       <Button
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_span="2"
           android:text="Submit" />
   </TableRow>


</TableLayout>

Code Breakdown:

The TableLayout is the parent layout that will form the table inside it.

The TableRow View layouts in Android are used to define one row of the table. It contains table cells inside it.

In all the table cell elements, we used the layout_weight property, which specifies how much space is allocated to that View in the parent layout. This space is calculated based on the below formulae.

Space assigned to child = (child’s individual weight) / (sum of the weight of every child in parent layout)

In the Button of the last TableRow, we used the layout_span attribute which simply means that a number of the specified cells will be merged and hence the view will take the width of the complete merged cell. Here we assigned layout_span = “2”, which means that two cells will be merged in the row.

Emulator Output:

ListView in Android

ListView in Android is a ViewGroup element that is used to display a scrollable list of other View or ViewGroups in multiple rows. The list items are automatically inserted into the ListView using an adapter Class.

Generally, this adapter class pulls data from the database or API in the form of an array or list and converts each item into a result view that’s placed into the ListView. This is very useful in making Android apps that are dynamic and progressive.

Android Adapter

The adapter in Android acts as a bridge between the data sources (database or API) and adapter Views like ListView, and Gridview to fill the data into View elements. This adapter holds the data in the form of an array or list, iterates through items in the data set, and generates the View for each item in the list.

Create ListView in an XML layout file

<ListView
    android:id="@+id/listView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Assign Adapter and Data to the ListView

// Create Data array
String[] users = { "JON DEO", "AHANA DEO", "Alavala Dasari",
                    "Pravala Seh", "Mady Sail", "Hamsi Yemieni"};


// Declare a reference to the ListView in layout file
ListView mListView = (ListView) findViewById(R.id.listView);


// Define an ArrayAdapter to hold and display the data in the list view
ArrayAdapter aAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, users);


// Set the defined ArrayAdapter to the ListView
mListView.setAdapter(aAdapter);

Code Breakdown:

The findViewById() method is used to link the UI element in the XML file with the Java/Kotlin Class or Activity.

The ArrayAdapter() constructor is used to create an adapter that will assign the value of the users list to the ListView.

The setAdapter() method is used to assign an adapter to the ListView.

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