As per the requirement of applications, sometimes we need to provide a custom feature to the buttons of AlertDialog. For instance, we may need to change the color of Positive, Negative, and/or Neutral buttons. And for the same reason, we may need to override button of AlertDialog to provide custom behavior.
In this tutorial, we are going to override the buttons of AlertDialog. So, this tutorial covers following points.
– Create AlertDialog
– Override the Buttons of AlertDialog
– Change text color of AlertDialog buttons
Create Android Application Project
If you are new to Android Studio, then you could learn about creating new projects from our tutorial Create Android Application Project in Android Studio Continued.
Create Android application project with following attributes.
| Project Name | AlertButtonOverride |
|---|---|
| Package Name | com.pcsalt.example.alertbuttonoverride |
| Minimum SDK Version | 19 |
| Activity Type | Empty Activity |
| Activity Name | MainActivity |
| Layout Name | activity_name |
Prepare layout screen
activity_main.xml: Layout for MainActivity.java. For this demo application, we need a Button only. Instead of using findViewById() for this button, we are binding buttonClicked with ClickListener of Button.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:onClick="buttonClicked"
android:text="Hello World!" />
</RelativeLayout>
Create AlertDialog
As you might have noted that there is onClick property defined in the XML for Button. So we have to provide a public method by name butonClicked and this method should have one parameter of type View.
fun buttonClicked(view: View?) {
val dialogBuilder = AlertDialog.Builder(this).apply {
setTitle("Demo")
setMessage("After clicking the \"Done\" button, dialog will not close.")
setPositiveButton("Done", null)
setNegativeButton("Close", null)
}
val alertDialog = dialogBuilder.create()
alertDialog.show()
val positiveButton = alertDialog.getButton(DialogInterface.BUTTON_POSITIVE)
// override the text color of positive button
positiveButton.setTextColor(
ContextCompat.getColor(
this@MainActivity,
android.R.color.holo_green_dark
)
)
// provides custom implementation to positive button click
positiveButton.setOnClickListener { onPositiveButtonClicked(alertDialog) }
val negativeButton = alertDialog.getButton(DialogInterface.BUTTON_NEGATIVE)
// override the text color of negative button
negativeButton.setTextColor(
ContextCompat.getColor(
this@MainActivity,
android.R.color.holo_red_dark
)
)
// provides custom implementation to negative button click
negativeButton.setOnClickListener { onNegativeButtonClicked(alertDialog) }
}NOTE: Always override AlertDialog Button after calling AlertDialog.show() method. Otherwise, it will throw NullPointerException while adding ClickListener to the overriden button.
In this method buttonClicked, we are creating an AlertDialog with a title, message, and two buttons. Then, after calling AlertDialog.show(), we are overriding button of AlertDialog for:
– Custom action on button click, and
– Change text color of the button text.
MainActivity.kt
Here is the complete code of MainActivity.ktwith imports and onPositiveButtonClicked() and onNegativeButtonClicked().
package com.pcsalt.example.alertbuttonoverride
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.content.DialogInterface
import android.view.View
import android.widget.Toast
import androidx.appcompat.app.AlertDialog
import androidx.core.content.ContextCompat
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
/*
This method is referenced from Button in activity_main.xml
*/
fun buttonClicked(view: View?) {
val dialogBuilder = AlertDialog.Builder(this).apply {
setTitle("Demo")
setMessage("After clicking the \"Done\" button, dialog will not close.")
setPositiveButton("Done", null)
setNegativeButton("Close", null)
}
val alertDialog = dialogBuilder.create()
alertDialog.show()
val positiveButton = alertDialog.getButton(DialogInterface.BUTTON_POSITIVE)
// override the text color of positive button
positiveButton.setTextColor(
ContextCompat.getColor(
this@MainActivity,
android.R.color.holo_green_dark
)
)
// provides custom implementation to positive button click
positiveButton.setOnClickListener { onPositiveButtonClicked(alertDialog) }
val negativeButton = alertDialog.getButton(DialogInterface.BUTTON_NEGATIVE)
// override the text color of negative button
negativeButton.setTextColor(
ContextCompat.getColor(
this@MainActivity,
android.R.color.holo_red_dark
)
)
// provides custom implementation to negative button click
negativeButton.setOnClickListener { onNegativeButtonClicked(alertDialog) }
}
private fun onPositiveButtonClicked(alertDialog: AlertDialog) {
Toast.makeText(this@MainActivity, "Dialog will NOT close", Toast.LENGTH_SHORT).show()
}
private fun onNegativeButtonClicked(alertDialog: AlertDialog) {
Toast.makeText(this@MainActivity, "Dialog will close now", Toast.LENGTH_SHORT).show()
alertDialog.dismiss()
}
}Screenshots:
Download Source Code
