Kotlin redundant FindViewById
To avoid any personal words or sentences at the beginning and end of the reply, here is a detailed explanation of why Kotlin's findViewById
can be considered redundant.
Background
In Android development, the findViewById
method is used to retrieve a reference to a view defined in an XML layout file. It is typically used in Java to access views programmatically. However, Kotlin provides several features that make findViewById
redundant in most cases.
Kotlin Synthetic Properties
Kotlin introduces a feature called "synthetic properties," which allows direct access to views without the need for findViewById
. When using synthetic properties, the views defined in the XML layout file can be accessed directly by their id
attribute.
To enable synthetic properties, you need to add the kotlin-android-extensions
Gradle plugin to your project's dependencies. Once added, you can access views directly by their id
using the findViewById
method.
Example
Let's say you have a TextView with the id
"myTextView" in an XML layout file. In Java, you would typically access it like this:
TextView myTextView = findViewById(R.id.myTextView);
In Kotlin, with synthetic properties enabled, you can access it directly:
val myTextView: TextView = myTextView
By referencing the id
directly, you avoid the need to call findViewById
. This approach reduces boilerplate code and makes the code more concise.
Limitations of Synthetic Properties
It's important to note that synthetic properties have some limitations. They only work within the same layout file and module. If you need to access a view from a different layout file or module, you would still need to use findViewById
.
Additionally, starting from Android Gradle Plugin 3.6.0, synthetic properties are deprecated. The recommended approach is to use View Binding or Data Binding.
View Binding
View Binding is another feature introduced by Android that provides a type-safe way to access views. It generates a binding class for each XML layout file, allowing you to access views directly through the binding object.
To enable View Binding, you need to enable it in your module's build.gradle file by adding the following code:
android {
...
viewBinding {
enabled = true
}
}
Once enabled, you can access views using the generated binding class:
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
val myTextView = binding.myTextView
}
By using View Binding, you can access views directly without the need for findViewById
, and it provides a type-safe way to access views.
Conclusion
In conclusion, Kotlin provides alternatives to the traditional findViewById
method. Synthetic properties and View Binding offer more concise and type-safe ways to access views, reducing the need for findViewById
and making your code more efficient and readable.