Develop Reference

Blank screen on device after running kotlin app

I'm working on a kotlin app that simply display a pop-up when buttons are pressed, but for some reason whenever i run the app all i get is a blank white screen. I've tried so many solutions online all to no avail.
Here's my Main Activity code:
import android.app.AlertDialog
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import com.example.popup.R
import com.example.popup.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
private var activityMainBinding: ActivityMainBinding? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.lay_custom_dialog)
title = "POP UP"
activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
// add the following three lines
activityMainBinding?.btnShowDefaultDialog?.setOnClickListener {
showDefaultDialog()
}
}
override fun onDestroy() {
activityMainBinding = null
super.onDestroy()
}
private fun showDefaultDialog() {
val alertDialog = AlertDialog.Builder(this)
alertDialog.apply {
setIcon(R.drawable.ic_hello)
setTitle("Hello")
setMessage("I just wanted to greet you. I hope you are doing great!")
setPositiveButton("Positive") { _, _ ->
toast("clicked positive button")
}
setNegativeButton("Negative") { _, _ ->
toast("clicked negative button")
}
setNeutralButton("Neutral") { _, _ ->
toast("clicked neutral button")
}
}.create().show()
}
private fun toast(text: String) = Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
}
And here's the activity_main.xml file(the button views are displayed on the view pager, but not on the device when run)
\<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"\>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/btnShowDefaultDialog"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="#string/show_dialog"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.912" />
<Button
android:id="#+id/btnShowCustomDialog"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="#string/show_custom_dialog"
app:layout_constraintBottom_toTopOf="#id/btnShowDefaultDialog"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.238"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.977" />
</androidx.constraintlayout.widget.ConstraintLayout>
Here's the Android Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<application
android:allowBackup="true"
android:dataExtractionRules="#xml/data_extraction_rules"
android:fullBackupContent="#xml/backup_rules"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.Popup"
tools:targetApi="31">
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<meta-data
android:name="android.app.lib_name"
android:value="" />
</activity>
</application>
</manifest>

In onCreate() you call
setContentView(R.layout.lay_custom_dialog)
however, you say that the layout file for your Activity is called activity_main.xml. You should be doing this:
setContentView(R.layout.activity_main)

SpeechRecognizer is not available on my android emulator. Kotlin

I am new to android application development and I am trying to create a voice assistant in Kotlin. When I try to use my microphone it seems that my SpeechRecognizer doesn't work. I followed the directions of this video, but when I test my app on emulator it seems that SpeechRecognizer isn't avaiable. I also tried this issue on github, but it didn't help me.
The result is always the same. I always get the text string I wrote in case the SpeechRecognizer.isRecognitionAvailable is not available.
Here is what i have tried to do:
Add all permition to my application from android settings
Enable the microphone from emulator settings
Here is my scrips:
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.firstkotlinproject">
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.speech.RecognitionService"/>
<application
android:allowBackup="true"
android:dataExtractionRules="#xml/data_extraction_rules"
android:fullBackupContent="#xml/backup_rules"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.FirstKotlinProject"
tools:targetApi="31">
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:background="#525252">
<TextView
android:id="#+id/textView_to_change"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#FFA500"
android:textSize="24sp"
android:text="Hello"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button_to_click"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView_to_change"
android:textColor="#FFA500"
android:backgroundTint="#000"/>
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity
package com.example.firstkotlinproject
import android.app.Activity
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.speech.RecognizerIntent
import android.speech.SpeechRecognizer
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
import java.util.*
import kotlin.collections.ArrayList
class MainActivity : AppCompatActivity() {
private val requestCodeDefoult = 102
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button_to_click.setOnClickListener {
askSpeechInput()
}
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == requestCodeDefoult && resultCode == Activity.RESULT_OK) {
val result :ArrayList<String>? = data?.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS)
textView_to_change.text = result?.get(0).toString()
}
}
private fun buttonPressed() :Boolean {
var result = false
if (button_to_click.isPressed) {
result = true
}
return result
}
private fun askSpeechInput() {
if (!SpeechRecognizer.isRecognitionAvailable(this)) {
Toast.makeText(this, "Speech recognition is not avaiable!", Toast.LENGTH_SHORT).show()
} else if (!buttonPressed()) {
Toast.makeText(this, "Press the button to speak", Toast.LENGTH_SHORT).show()
} else {
val i = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH)
i.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM)
i.putExtra(RecognizerIntent.EXTRA_LANGUAGE, Locale.ITALIAN)
i.putExtra(RecognizerIntent.EXTRA_PROMPT, "Say something...")
startActivity(i)
}
}
}

the receiver does not show the message. BroadcastReceiver

**Hello everyone, I'm new to programming. When I press the button, nothing happens, I can't find the error. Please see. On assignment, I need to create a message listener (Receiver) and send text data to it by clicking on a button. Show the received data in Toast. .xml file:
**
<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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="#string/btn_send_message"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
.kt file:
package kg.tutorialapp.homework_47
import android.content.Intent
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
private val myAction = "kg.tutorialapp.action.MESSAGE"
private val alarmMessage = "Hello world!"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button = findViewById<Button>(R.id.button)
button.setOnClickListener { sendMessage() }
}
private fun sendMessage() {
val intent = Intent()
intent.action = myAction
intent.putExtra("kg.tutorialapp.broadcast.MESSAGE", alarmMessage)
intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES)
sendBroadcast(intent)
}
}
receiver file:
class Receiver : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
Toast.makeText(context, "Новое сообщение: " + intent.getStringExtra("kg.tutorialapp.broadcast.MESSAGE"), Toast.LENGTH_LONG).show()
}
}
> manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="kg.tutorialapp.homework_47">
<application
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.Homework_47"
tools:ignore="AllowBackup">
<receiver
android:name=".Receiver"
android:enabled="true"
android:exported="true"
tools:ignore="ExportedReceiver">
<intent-filter>
<action android:name="kg.tutorialapp.action.MESSAGE"/>
</intent-filter>
</receiver>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

Try removing android:permission="TODO" from your reciever's manifest declaration.
Refer here

Telephone API does nothing

I made a simple telephone app for android, I was do Permission internet in Android Manifest file on android studio, I use this method for make my app can be used for calling android.Manifest.permission.CALL_PHONE.
but when I run my code nothing happens
this is the first class :
class MainActivity : AppCompatActivity() {
val mobno: String = "1234567890"
val REQUEST_PHONE_CALL = 1
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val call = findViewById<Button>(R.id.phone_call)
call.setOnClickListener {
if (ActivityCompat.checkSelfPermission(
this,
android.Manifest.permission.CALL_PHONE
) != PackageManager.PERMISSION_GRANTED
) {
}
}
}
private fun makecall() {
val intent = Intent(Intent.ACTION_CALL, Uri.fromParts("tel", mobno, null))
startActivity(intent)
}
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<out String>,
grantResults: IntArray
) {
if (requestCode == REQUEST_PHONE_CALL) {
makecall()
}
}
}
this is my main_activity.xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
tools:context=".MainActivity">
<Button
android:id="#+id/phone_call"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="200dp"
android:text="Place Call" />
</LinearLayout>
this is my manifest :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.telephoneappkotlin">
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
in my graddle I don't use any Library implementation.

Add this in your manifest
<uses-permission android:name="android.permission.CALL_PHONE" />

Second activity not showing on real phone

My app works absolutely fine on the emulator. but when i get it to a real phone (tried on multiple: one plus 7t pro running android 10, Samsung M20 running android 10), the second activity doesnt launch at all.
I tried a simple app that just launches a second activity & nothing happens even in this. Im out of ideas on what to do!
Here is my main activity:
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
fun btnClick(view: View){
intent.setClass(this,ViewExpenseList::class.java)
intent.putExtra("Text",findViewById<TextView>(R.id.helloWorld).text.toString())
startActivityForResult(intent,1)
}
}
activity 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/helloWorld"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="159dp"
android:layout_marginTop="21dp"
android:layout_marginEnd="164dp"
android:layout_marginBottom="286dp"
android:onClick="btnClick"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/helloWorld" />
</androidx.constraintlayout.widget.ConstraintLayout>
My second activity:
package com.anand.expensetracker
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
class ViewExpenseList : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_view_expense_list)
findViewById<TextView>(R.id.textView).text=intent.getStringExtra("Text") +"asdfghj"
}
}
My android manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.anand.expensetracker"
android:versionCode="1"
android:versionName="#string/versionName">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".ViewExpenseList"></activity>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

try change
intent.setClass(this,ViewExpenseList::class.java)
to
val intent = Intent(this, ViewExpenseList::class.java)

Do it like this below
fun btnClick(view: View){
//Get text from view
val myText = helloWorld.text.toString()
//Launch ViewExpenseList Activity
val intent = Intent(this,ViewExpenseList::class.java)
intent.putExtra("Text",myText)
startActivity(intent)
}