Android Custom Components

In this article, you will learn about Android custom components and how they can be created and used in your apps.

Android applications consist of various UI components, such as buttons, text fields, checkboxes, and more, that can be customized to fit your requirements. However, sometimes the available components may not meet your specific needs, and you may need to create your own components. Fortunately, Android provides a way to create custom components that can be tailored to meet your unique use cases.

Android offers a wide range of prebuilt UI components that can be used to design the user interface of the app. In some cases, however, the built-in components may not meet the app’s needs. It is best to create custom components in such cases. Android custom components are useful for creating highly reusable and modular UI elements. Developers can use these components to create or extend existing UI widgets. As a result, complex UI layouts can be built with high levels of customization and consistency.

Creating Android Custom Components

Creating custom Android components involves creating a new class that extends an existing component class or a ViewGroup class.

For example, if you want to create a custom button, you can extend the Button class. Similarly, if you want to create a custom layout, you can extend the ViewGroup class.

After extending the base class, you can define your custom properties and methods to meet your specific requirements. You can also override the existing methods to modify their behavior to suit your needs.

For instance, if you want to change the button’s background color, you can override the onDraw() method to change the color.

Step 1: Create a new Java class

A custom component is created by extending an existing Android view component with a new Java class.

To create a custom text view component, we would extend the TextView class.

Here is an example:

public class CustomTextView extends TextView {

public CustomTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

private void init() {
// Add custom initialization code here
}

}

The above code creates a new Java class called CustomTextView that extends the TextView class.

Additionally, we have provided a constructor that accepts a context and attribute set as arguments.

Our custom initialization code will be added to the init() method.

Step 2: Define Custom Attributes

A custom attribute for our component needs to be defined once the Java class has been created.

This is done in the res/values/attrs.xml file.

Here is an example:

<resources>
<declare-styleable name="CustomTextView">
<attr name="customFont" format="string" />
</declare-styleable>
</resources>

For our CustomTextView component, we have defined a custom attribute called customFont.

It is indicated in the format string that this attribute has a string value.

Step 3: Apply Custom Attributes

Our next step is to apply our custom attributes to our component.

This is done in our Java class constructor.

Here is an example:

public class CustomTextView extends TextView {

private String customFont;

public CustomTextView(Context context, AttributeSet attrs) {
super(context, attrs);

TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CustomTextView);
customFont = a.getString(R.styleable.CustomTextView_customFont);
a.recycle();

init();
}

private void init() {
if (customFont != null) {
// Apply custom font here
}
}

}

The above code adds a member variable called customFont to our Java class.

Our constructor has also been updated to obtain the customFont attribute value from the attribute set.

In the init() method, we have added an if statement that applies the custom font if it is specified.

Step 4: Use the Custom Component in Layouts

The final step is to use our custom component in layouts.

Once you have created your custom components, you can use them in your apps just like any other standard components.

You can either add them programmatically or define them in your XML layouts.

Here is an example:

<com.example.CustomTextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:customFont="Arial"
android:text="Hello World!" />

This layout file uses the CustomTextView component.

In addition, we have set the customFont attribute to Arial and specified the text to be displayed.

Once a custom component has been created, it can be used like any other view or view group in your app.

You can either add it to your layout XML file and configure its custom attributes, or you can create instances of it in your Java code and add it programmatically.

Advantages of Custom Components:

Custom Components are used due to a variety of reasons:

Advantages	Overview
Flexibility	Custom components give you the flexibility to design unique UI elements that match your app’s branding and visual style. You can create custom components that are not available in the standard Android UI components.
Reusability	Custom components are reusable, which means that you can use them in multiple places in your app. This makes it easy to maintain a consistent look and feel across your app.
Scalability	Custom components can be scaled easily to fit different screen sizes and resolutions. This means that your app will look great on all devices, regardless of their screen size or resolution.

Table Of Content-

Android Custom Components: