Android Tutorial & Knowledge: April 2018

Login Screen handle with text watcher in multiple textinputedittext and validate username and password in Kotlin and handle button Onclick XML with function

1: Create activity_main.xml to design login form fields as username, password, and button

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

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:layout_width="match_parent"

android:layout_height="match_parent"

tools:context="www.paymonk.com.kridhankotlin.MainActivity">

<android.support.v7.widget.CardView

android:id="@+id/cardView"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_centerVertical="true"

android:layout_margin="25dp"

app:cardCornerRadius="5dp"

app:cardElevation="1dp"

app:cardUseCompatPadding="true">


<LinearLayout

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical">



<android.support.design.widget.TextInputLayout

android:id="@+id/usernamewrapper"

android:layout_width="match_parent"


android:layout_height="wrap_content">


<android.support.design.widget.TextInputEditText

android:id="@+id/et_username"

android:layout_width="match_parent"

android:layout_height="wrap_content"


android:hint="Username" />


</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout

android:id="@+id/passwordwrapper"

android:layout_width="match_parent"

android:layout_height="wrap_content">

<android.support.design.widget.TextInputEditText

android:id="@+id/et_password"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="Password" />
</android.support.design.widget.TextInputLayout>

<Button

android:id="@+id/btn_login"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:onClick="login"

android:text="Login" />

</LinearLayout>

</android.support.v7.widget.CardView>
</RelativeLayout>

2: Create MainActivity.kt

class MainActivity : AppCompatActivity() {


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


3: Validate fields using validate function


fun validate() {
    var userName = et_username.text.toString()
    var password = et_password.text.toString()

if (userName.equals("") || userName.equals(null)) {
usernamewrapper.error = "Username is not null"        
usernamewrapper.isErrorEnabled = true    
} else if (password.equals("") || password.equals(null)) {
passwordwrapper.error = " Password is not null"        
passwordwrapper.isErrorEnabled = true    
} else {
usernamewrapper.isErrorEnabled = false        
passwordwrapper.isErrorEnabled = false        
Toast.makeText(this, " Login successfully : username-> " 
+ userName + " password-> " 
+ password, 
Toast.LENGTH_SHORT).show()
    }
}

4: onclick xml in create function onclick="login"

fun login(v: View) {
    validate()
}


5: Textwatcher handle multiple textinputedittext by id


inner class Textwatcher(var v: View) : TextWatcher {

    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
        //do something    }

    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
        //do something    }

    override fun afterTextChanged(s: Editable?) {
        when (v.getId()) {
            R.id.et_username -> if (!s.isNullOrEmpty()) {
                usernamewrapper.setErrorEnabled(false)
            }

            R.id.et_password -> if (!s.isNullOrEmpty()) {
                passwordwrapper.setErrorEnabled(false)
            }
        }
    }

}



6:Then complete MainActivity.kt


package www.abhishek.com.kotlin

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.text.Editable
import android.text.TextWatcher
import android.view.View
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*


/** * Created by abhishek * https://abhiandroidknowledge.blogspot.com/2018/04/login-screen-handle-with-text-watcher.html
 * */
class MainActivity : AppCompatActivity() {


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

        initialise()
    }

    fun initialise() {
        et_username.addTextChangedListener(Textwatcher(et_username))
        et_password.addTextChangedListener(Textwatcher(et_password))
    }

    fun login(v: View) {
        validate()
    }

    fun validate() {
        var userName = et_username.text.toString()
        var password = et_password.text.toString()


if (userName.equals("") || userName.equals(null)) {
usernamewrapper.error = "Username is not null"            
usernamewrapper.isErrorEnabled = true        
} else if (password.equals("") || password.equals(null)) {
passwordwrapper.error = " Password is not null"            
passwordwrapper.isErrorEnabled = true        
} else {
usernamewrapper.isErrorEnabled = false            
passwordwrapper.isErrorEnabled = false            
Toast.makeText(this, " Login successfully : username-> " 
+ userName + " password-> " 
+ password, 
Toast.LENGTH_SHORT).show()
        }
    }

    inner class Textwatcher(var v: View) : TextWatcher {

        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
            //do something        }

        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
            //do something        }

        override fun afterTextChanged(s: Editable?) {
            when (v.getId()) {
                R.id.et_username -> if (!s.isNullOrEmpty()) {
                    usernamewrapper.setErrorEnabled(false)
                }

                R.id.et_password -> if (!s.isNullOrEmpty()) {
                    passwordwrapper.setErrorEnabled(false)
                }
            }
        }

    }

}



7:Complete login form and validate the form and textwatcher watch the error


Thank you

Android Tutorial & Knowledge

Monday 2 April 2018

Login Screen handle with text watcher in multiple textinputedittext and validate username and password in Kotlin and handle button onclick xml with function

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