Wednesday, September 2, 2020

android kotlin - EditText allow only characters and numbers

MainActivity.kt

package com.example.jetpack

import android.os.Bundle
import android.text.InputFilter
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*


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

        // allow only characters and numbers with underscore and hyphen
        editText.filters = arrayOf(filter)
    }
}


// input filter to allow only characters and numbers
// this also allow underscore and hyphen
val filter = InputFilter { charSequence, i, i2, spanned, i3, i4 ->
    for (index in i until i2) {
        if (
            // allow all letters and digits
            !Character.isLetterOrDigit(charSequence[index])
            // allow underscore
            // to disallow underscore comment the below line
            && charSequence[index].toString() != "_"
            // allow hyphen
            // to disallow hyphen comment the below line
            && charSequence[index].toString() != "-"
        ) {
            return@InputFilter ""
        }
    }
    null
}
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"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FEFEFA"
    tools:context=".MainActivity">

    <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"
        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" />

</androidx.constraintlayout.widget.ConstraintLayout>