android kotlin - EditText border color programmatically

The code demonstrates how to programmatically set or change the border color of an EditText in Android. It defines two EditTexts in the activity_main.xml layout file and creates references to them in the MainActivity.kt file.

The code then uses an extension function called borderDrawable() to generate a drawable object with the specified border width, color, and background color. This drawable object is then set as the background of the EditText to give it a border.

Here is a breakdown of the code:

  • MainActivity.kt:

    • The borderDrawable() extension function takes three optional parameters:
      • width: The width of the border in pixels (default is 10).
      • color: The color of the border (default is black).
      • bgColor: The background color of the EditText (default is transparent).
    • The function creates a GradientDrawable object and sets its shape to RECTANGLE.
    • It then sets the stroke width, color, and background color of the GradientDrawable using the provided parameters or the default values.
    • Finally, it returns the GradientDrawable object.

  • activity_main.xml:

    • This file defines the layout of the activity.
    • It contains two EditText widgets with different IDs.

Summary

This code snippet provides a straightforward way to customize the appearance of EditTexts in an Android app by programmatically changing their border color. The use of extension functions makes the code more concise and reusable.░


MainActivity.kt 

package com.cfsuman.kotlintutorials

import android.app.Activity
import android.content.Context
import android.graphics.Color
import android.graphics.drawable.Drawable
import android.graphics.drawable.GradientDrawable
import android.os.Bundle
import android.text.InputFilter
import android.util.TypedValue
import android.widget.EditText


class MainActivity : Activity() {
    private lateinit var editText:EditText
    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
        editText = findViewById(R.id.editText)
        editText2 = findViewById(R.id.editText2)

        // add specified color border to edit text programmatically
        editText.background = borderDrawable(
            2.dpToPixels(applicationContext), Color.BLUE
        )

        // add border and background color to edit text programmatically
        editText2.background = borderDrawable(
            width = 2.dpToPixels(applicationContext),
            color = Color.parseColor("#DA1884"),
            bgColor = Color.WHITE
        )
    }
}


// extension function to generate a drawable to show border
fun borderDrawable(
    width: Int = 10, // border width in pixels
    color: Int = Color.BLACK, // border color
    bgColor: Int = Color.TRANSPARENT // view background color
): Drawable {
    return GradientDrawable().apply {
        shape = GradientDrawable.RECTANGLE
        setStroke(width, color)
        setColor(bgColor)
    }
}


// extension function to convert dp to equivalent pixels
fun Int.dpToPixels(context: Context):Int = TypedValue.applyDimension(
    TypedValue.COMPLEX_UNIT_DIP, this.toFloat(),
    context.resources.displayMetrics
).toInt()
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"
    xmlns:tools="http://schemas.android.com/tools"
    android:background="#DCDCDC"
    android:padding="32dp">

    <EditText
        android:id="@+id/editText"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="12dp"
        android:layout_marginEnd="12dp"
        android:inputType="text|textVisiblePassword"
        android:padding="12dp"
        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:inputType="text|textVisiblePassword"
        android:padding="12dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

</androidx.constraintlayout.widget.ConstraintLayout>
android kotlin - EditText border color programmatically
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