Monday, August 31, 2020

android kotlin - EditText min length

MainActivity.kt

package com.example.jetpack

import android.content.Context
import android.content.Context.INPUT_METHOD_SERVICE
import android.os.Bundle
import android.view.KeyEvent
import android.view.View
import android.view.inputmethod.EditorInfo
import android.view.inputmethod.InputMethodManager
import android.widget.EditText
import android.widget.Toast
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)

        // apply edit text filter minimum characters length
        editText.filterMinLength(6)
    }
}


// extension function to filter edit text minimum characters length
fun EditText.filterMinLength(min: Int){
    // check minimum length on focus change
    onFocusChangeListener = View.OnFocusChangeListener { view, b ->
        if (!b) { setLengthError(min) }
    }

    // check minimum length on keyboard done click
    setOnEditorActionListener { v, actionId, event ->
        if (actionId == EditorInfo.IME_ACTION_DONE) { setLengthError(min) }
        false
    }

    // check minimum length on enter key press
    setOnKeyListener { p0, p1, p2 ->
        if (p2.action == KeyEvent.ACTION_DOWN && p1 == KeyEvent.KEYCODE_ENTER) {
            setLengthError(min)
            true
        } else {
            false
        }
    }
}


// extension function to check edit text minimum length of characters
fun EditText.setLengthError(min: Int){
    error = try {
        val value = text.toString().trim()
        if (value.length < min){
            "minimum length $min characters."
        }else{
            // hide soft keyboard
            context.hideSoftKeyboard(this)

            Toast.makeText(context,"You submitted : $value",
                Toast.LENGTH_SHORT).show()
            null
        }
    }catch (e: Exception){
        "minimum length $min characters."
    }
}


// extension function to hide soft keyboard programmatically
fun Context.hideSoftKeyboard(editText: EditText){
    (getSystemService(INPUT_METHOD_SERVICE) as InputMethodManager).apply {
        hideSoftInputFromWindow(editText.windowToken, 0)
    }
}
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"
    android:clickable="true"
    android:focusable="true"
    android:focusableInTouchMode="true"
    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:inputType="text|textVisiblePassword"
        android:padding="12dp"
        android:textSize="30sp"
        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>