android kotlin - EditText select all on focus

Selecting All Text on Focus in an EditText (Kotlin)

This code demonstrates two ways to achieve the same functionality in an Android app: selecting all the text inside an EditText when it receives focus. We'll explore both approaches, implemented in Kotlin and using an XML layout file.

Code Breakdown

The code consists of two parts: the MainActivity.kt file and the activity_main.xml layout file.

MainActivity.kt:

  1. Import Statements: We import necessary classes like Activity, Bundle, and EditText.
  2. Class Definition: We define an Activity subclass named MainActivity.
  3. Variable Declaration: An EditText variable named editText2 is declared but not yet initialized.
  4. onCreate Method: This method is called when the activity is first created.
    • super.onCreate(savedInstanceState): This line calls the superclass's onCreate method.
    • setContentView(R.layout.activity_main): Sets the layout of the activity using the activity_main.xml file.
    • findViewById: We retrieve the EditText with the ID editText2 from the layout and assign it to the editText2 variable.
    • setSelectAllOnFocus(true): This line programmatically sets the behavior of editText2 to select all the text when it gains focus.

activity_main.xml:

  1. Root Layout: We define a ConstraintLayout as the root layout of the activity.
  2. First EditText (not used in this example): This EditText with ID editText is commented out in the provided code. It shows an alternative way to achieve the same functionality using XML attributes.
    • android:selectAllOnFocus="true": This attribute directly sets the behavior to select all text on focus for this specific EditText.
  3. Second EditText (used in this example): This EditText with ID editText2 is the one referenced in the Kotlin code.
    • Most attributes define its appearance and behavior (text size, input type, etc.).

Summary

The code provides two ways to make an EditText select all its text when it receives focus. The first approach, implemented in MainActivity.kt, uses the setSelectAllOnFocus(true) method programmatically. The second approach, defined in activity_main.xml, uses the android:selectAllOnFocus="true" attribute within the XML layout file. Both methods achieve the same result: making the editing experience smoother by allowing users to quickly replace existing text when they tap on the EditText.


MainActivity.kt 

package com.cfsuman.kotlintutorials

import android.app.Activity
import android.os.Bundle
import android.widget.EditText


class MainActivity : Activity() {
    private lateinit var editText2:EditText

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // get the widgets reference from XML layout
        editText2 = findViewById(R.id.editText2)

        // set edit text select all text on focus programmatically
        editText2.setSelectAllOnFocus(true)
    }
}
activity_main.xml 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCDCDC"
    android:padding="32dp">

    <!-- select all text inside edit text on focus in xml -->
    <EditText
        android:id="@+id/editText"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="12dp"
        android:layout_marginEnd="12dp"
        android:padding="12dp"
        android:textSize="30sp"
        android:inputType="text|textVisiblePassword"
        android:fontFamily="sans-serif-condensed-medium"
        android:selectAllOnFocus="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.12" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="12dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="12dp"
        android:padding="12dp"
        android:textSize="30sp"
        android:inputType="text|textVisiblePassword"
        android:fontFamily="sans-serif-condensed-medium"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

</androidx.constraintlayout.widget.ConstraintLayout>
android kotlin - EditText select all on focus
More android kotlin tutorials