Create a custom View by inflating a layout?

💡 Creating a Custom View by Inflating a Layout: A Complete Guide

Are you struggling to create a custom view by inflating a layout in your Android application? Don't worry, you're not alone! In this article, we'll address common issues and provide easy solutions for this problem.

The Problem

Let's first understand the problem at hand. You want to replace a certain layout that you use at multiple places with a custom view. Specifically, you want to replace the following RelativeLayout:

<RelativeLayout
 android:id="@+id/dolphinLine"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:layout_centerInParent="true"
 android:background="@drawable/background_box_light_blue"
 android:padding="10dip"
 android:layout_margin="10dip">
   <!-- Contents of the RelativeLayout -->
</RelativeLayout>

with a custom view:

<view class="com.example.MyQuantityBox"
    android:id="@+id/dolphinBox"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:myCustomAttribute="@string/my_title"/>

The aim is to have a custom view (which should not have any child views) where the only customizable property is the title, which can be specified in the XML.

The Solution

To achieve this, we can follow these simple steps:

1. Create a Custom View Class

First, create a custom view class in your Android project. Let's name it MyQuantityBox. This class should extend RelativeLayout to encapsulate the desired layout and functionality.

class MyQuantityBox(context: Context, attrs: AttributeSet?) : RelativeLayout(context, attrs) {
   // Custom view logic goes here
}

2. Layout XML

Next, create a layout XML file in the /res/layout directory of your project. Name it my_quantity_box.xml (or whatever name you prefer).

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/dolphinLine"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/background_box_light_blue"
    android:padding="10dip"
    android:layout_margin="10dip">
    <!-- Contents of the RelativeLayout -->
</RelativeLayout>

3. Inflate the Layout

In the MyQuantityBox class, override the onFinishInflate() method to inflate the layout XML file and add it to the custom view.

class MyQuantityBox(context: Context, attrs: AttributeSet?) : RelativeLayout(context, attrs) {
   
   init {
        inflate(context, R.layout.my_quantity_box, this)
    }
   
   override fun onFinishInflate() {
        super.onFinishInflate()
        // Custom view setup goes here
    }
}

This allows you to inflate the custom layout and add it to your custom view whenever it is inflated.

4. Customizable Properties

To make the title customizable, we need to define a custom attribute in the /res/values/attrs.xml file.

<resources>
    <declare-styleable name="MyQuantityBox">
        <attr name="myCustomAttribute" format="string"/>
    </declare-styleable>
</resources>

Now, in your MyQuantityBox class, retrieve the value of the custom attribute and set it to the appropriate view.

class MyQuantityBox(context: Context, attrs: AttributeSet?) : RelativeLayout(context, attrs) {
   
   private val titleTextView: TextView
   
   init {
        inflate(context, R.layout.my_quantity_box, this)
        titleTextView = findViewById(R.id.dolphinTitle)
        
        attrs?.let {
            val typedArray = context.obtainStyledAttributes(it, R.styleable.MyQuantityBox, 0, 0)
            val title = typedArray.getString(R.styleable.MyQuantityBox_myCustomAttribute)
            titleTextView.text = title
            typedArray.recycle()
        }
    }
   
   override fun onFinishInflate() {
        super.onFinishInflate()
        // Custom view setup goes here
    }
}

5. Usage

Now, you can use your custom view MyQuantityBox in your layout XML as follows:

<com.example.MyQuantityBox
    android:id="@+id/dolphinBox"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    app:myCustomAttribute="@string/my_title"/>

Simply replace com.example with the actual package name of your project.

Call to Action

Congratulations! You have successfully created a custom view by inflating a layout. Now, go ahead and implement this solution in your project. If you encounter any issues or have questions, feel free to leave a comment below. Happy coding! 🚀